code of practice for electrical safety

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Code of Practice

ForElectrical Safety

Guidance for UniversityDepartments and Functions

September 2006

Safety Services Office


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UNIVERSITY OF LEICESTER

CODE OF PRACTICE FOR ELECTRICAL SAFETY

CONTENTS

Foreword

Introduction

1.1 General electrical hazards1.2 Scope of Code1.3 Framework and application1.4 Maintenance Section

1.5 Space heaters1.6 Radiant electric fires

Part A

A.1 Commercial electrical equipment

A.1.1 ApplicationA.1.2 Fuses, enclosure, isolationA.1.3 Visual check

A.2 Checks before use

A.2.1 Manufacturer's duties & informationA.2.2 Older equipmentA.2.3 Equipment taken out or loanedA.2.4 Use of equipment out of doorsA.2.5 'Hard use' equipment

A.3 Maintenance

A.3.1 Departmental responsibility

A.3.2 Elements of visual checkA.3.3 Testing. Frequency, records markingA.3.4 Tests on behalf of DepartmentsA.3.5 Shared equipment

A.4 Summary of Part A

A.4.1 Instructions etc. to usersA.4.2 Checks of equipmentA.4.3 Maintenance and testing


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Part B

B.1 Scope of this part of the Code

B.1.1 Application

B.1.2 Exceptions and further guidanceB.1.3 Installations - general standardB.1.4. Departmental responsibility, contractorsB.1.5 Notification to University Engineer

B.2 Electrical apparatus

B.2.1 Commercial equipmentB.2.2 Equipment constructed in DepartmentsB.2.3 Minimum electrical safety standards

B.3 Maintenance

B.3.1 Installations - limitation of responsibilityB.3.2 Visual checksB.3.3 Further maintenance and testingB.3.4 AdviceB.3.5 Testing: Guidance

B.4 Use of electrical equipment in laboratories and workshops

B.4.1 Adverse conditions

B.4.2 Conducting fluidsB.4.3 Electrical heating equipmentB.4.4 Flammable vapoursB.4.5 Supply cables, extension leadsB.4.6 Hand lamps, machine lamps, low voltage

B.5 Batteries

B.5.1 Fuses, circuit breakersB.5.2 Protection from accidental contactB.5.3 Finger rings

B.5.4 Battery charging - ventilation, warningB.5.5 Connecting, disconnecting

B.6 Connection of electrical equipment to humans

B.6.1 Particular hazardsB.6.2 Accidental earthingB.6.3 Safe systems of work - Preparation, documentationB.6.4 Further information

B.7 Routine checks of electrical equipment - guidelines


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B.7.1 Access to live partsB.7.2 Mechanical damageB.7.3 Cable gripB.7.4 Friction protectionB.7.5 Grommets, bushings

B.7.6 Connections, fusesB.7.7 Earth continuityB.7.8 Insulation resistanceB.7.9 Earth leakage, exceptions to testing requirements, British Standards

B.8 Minimum manufacturing standards

B.8.1 British Standard specifications for electrical safetyB.8.2 Commercial and 'in-house' manufactureB.8.3 EarthingB.8.4 Cables, plugs, colour coding

B.8.5 Switches, placing, identificationB.8.6 Phase disconnectionsB.8.7 FusesB.8.8 Isolators, effectiveness, terminals, screening, accidental contactB.8.9 Interlocking switches, construction, placing, maintenanceB.8.10 Conductors, terminals. Screening, warning noticesB.8.11 Heating elementsB.8.12 Liquids. Incorporation, placing. Flammable liquidsB.8.13 Fire and explosion. Special equipment. Sparkproof/flameproof fittingsB.8.14 Applicable legislation

Part C

C.1 Methods of working

C.1.1 Protection of personsC.1.2 TrainingC.1.3 Risk assessmentC.1.4 Work area, layout

C.2 Entry to premises

C.2.1 Authorised personsC.2.2 Supervision, barriers

C.3 Emergency arrangements

C.3.1 PlanningC.3.2 Stop buttons, lone working, first aidC.3.3 Electric shock. Instructions, display

C.4 Repairs

C.4.1 Removal of protective covers


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C.4.2 Accidental contactC.4.3 Restrictions of workC.4.4 TransformersC.4.5 Earth pathway limitations

C.5 Earth-free areas

C.5.1 Characteristics and guidanceC.5.2 Isolating transformersC.5.3 Soldering irons, lighting. Low voltageC.5.4 Barriers. Limitation of occupancy

C.6 Residual current devices (RCDs)

C.6.1 RCDs - function and purposeC.6.2 Advantages and limitations

C.6.3 Application to outdoor working

C.7 Repairs in the field

C.7.1 Portable RCDs

C.8 Experimental electrical equipment

C.8.1 Temporary rigs, constructionC.8.2 Temporary rigs, British StandardsC.8.3 Temporary rigs, Wiring diagrams etc.

C.8.4 Temporary rigs, Warning of dangerC.8.5 Control gear - 415v 3-phase equipment

C.9 Research experimental apparatus above 650V AC/DC

C.9.1 Enclosure of apparatusC.9.2 Security of enclosure

InterlockingEarthing rodsFurther guidance

Appendix 1: HSC/HSE Publications on electrical safety

Appendix 2: Other publications having an electrical safety content(incl. British and other Standards)

Appendix 3: Working space

Appendix 4: Guide to the Electricity at Work Regulations 1989


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FOREWORD

1. Although electricity causes relatively few occupational accidents, those that do occurare responsible for a high proportion of deaths. Electrical faults are also the secondmost frequent cause of fires in industry and commerce in the United Kingdom. The

majority of electrical accidents involve equipment that has become defective due toinsulation failure, inadequate earthing, incorrect over-current protection (fuses,

breakers, etc.) or faulty wiring. These pose a threat to personal safety causing electricshock, burns, explosions and fires.

2. The Electricity at Work Regulations 1989, came into force in all places of work on 1April 1990. They provide general rules on insulation, cutting off supply, andmaintenance of electrical systems, but they do not specify insulation materials nor thedesign of switches and isolators. Nor do they (contrary to what seems to be a widelyheld misconception) specify the nature and frequency of maintenance and testingother than to require that maintenance must be such as to prevent danger.

3. The purpose of this Code of Practice is to advise all who use or work with electricityon practical ways and means of avoiding electrical danger and of complying with theRegulations. The Code is subsidiary to, and forms part of, the University's Statementof Health and Safety Policy and Statement of Organisation and Arrangements

prepared and published by the University in compliance with the relevant sections ofthe Health and Safety at Work Act 1974.

4. The many and varied uses to which electricity is put in the University as elsewhereare such that no single document can cover all aspects. Lists of further publicationscovering specific electrical safety topics are appended.

Priced publications can be purchased from the Bookshop. Reference copies of mostcan be seen at the Safety Services Office by arrangement.

5. Certain parts of the Electricity at Work Regulations have been widely misinterpretedto imply that all existing electrical systems, plant and equipment, are renderedobsolete and must be replaced, regardless of cost, as soon as possible. This is mostdefinitely not the case. The following is abstracted from the Health and SafetyExecutive's Memorandum of Guidance on the Electricity at Work Regulations 1989(ISBN 0 7176 1602 9):

"Where electrical equipment pre-dates the Regulations this does not of itself meanthat the continued use of the equipment would be in contravention of the Regulations.For example, much of the equipment to which the Regulations apply may have beenmade to a standard, such as a British Standard, which has since been modified orsuperseded. It is likely to be reasonably practicable to replace it with equipmentmade to a more recent standard when, but only when, it becomes unsafe or falls duefor replacement for other than safety reasons, whichever occurs sooner. Equally,fixed installations to which the IEE Wiring Regulations are relevant may have beeninstalled in accordance with an earlier edition, now superseded but then current; thatin itself, does not means that the installation does not comply with the 1989Regulations."


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1. INTRODUCTION

1.1 Electricity is widely used throughout the University, and in normal

circumstances no hazards should arise. Neglect and misuse of electricity can,however, result in electric shock to individuals, or in overheating, leading tofire.

1.2 This Code of Practice details how Heads of Departments should assess andimplement their arrangements. It forms part of the general University policyon safety and its status is that of good practice that must either be followed or

be replaced by equivalent good practice. The Code, or relevant sections(whichever is appropriate) should be incorporated into individualDepartmental safety publications.

The nature of electricity is such that no Code of Practice can hope to coverevery conceivable aspect of its use. Guidance on specific aspects of electricalsafety can be found in relevant British Standards, official publications by theHealth and Safety Executive, professional bodies such as the Institute ofElectrical Engineers and many other sources.

It is of critical importance, however, that those engaged in work withelectricity to any degree should have the necessary level of competence tocarry out their work safely. It is also important to bear in mind that ensuringthe competence of those working with electricity is a statutory requirement,failure to observe which is a serious offence, carrying with it heavy penalties.

The following is extracted from the Health & Safety Executive's officialguidance on the Electricity at Work Regulations.

Only those who have both the knowledge and experience to make theright judgements and decisions and the necessary skill and ability to

carry them into effect should undertake work subject to this Code. A

little knowledge is often sufficient to make electrical equipment function

but a much higher level of knowledge and experience is usually needed toensure safety.

Special note: For convenience, the terms 'Department' and 'Head of

Department' are used throughout the code. The term 'Department'should be interpreted to include areas and premises such as student

accommodation, offices, shops, grounds and sports facilities and anyother place where electricity is used. The term 'Head of Department'

should be interpreted to mean the senior member of staff having

authority in such areas and premises and, therefore, the responsibility for

health and safety under the terms of the University's published policy onthe subject.

1.3

The Code has three separate parts, A, B and C. According to

circumstances, Departments will normally need to be concerned with

either Part A alone, Part B alone or Parts B and C together.


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Part A is for Departments with no technical staff and who use only

commercially produced equipment.

Part B is for Departments, who may construct, repair and maintain their

own equipment and who will normally have technical staff competent to

carry out the recommended maintenance and testing of equipment.

Part C deals with additional hazards, which may arise in Departments

who undertake the design, manufacture, repair and testing of electrical

apparatus.

1.4 This document is not intended to cover installation and other work by staff ofthe Maintenance Section of the Estates Office, who have their own workingsystems.

1.5 Privately-owned space heaters may not be used in the University. If under

special circumstances the Maintenance Section considers it necessary to provide a space heater, the Section will ensure that it is checked regularly.

1.6 The use of radiant electric fires is specifically prohibited. Their unauthoriseduse in the past has been the cause of a number of accidents including life-threatening fires.


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PART A

A.1 COMMERCIAL ELECTRICAL EQUIPMENT

A.1.1 This part of the Code applies essentially to Departments having no

technical staff and who use commercially produced electrical equipment.

A.1.2 Where standard commercial equipment is in use the correct fuse/overcurrentdevice should be fitted. Contact with live parts must be prevented byenclosure, isolation or by some other effective means.

A.1.3 The equipment should be visually checked before being put into use to ensureinitial safe condition.

A.2 CHECKS BEFORE USE

A.2.1 Manufacturers of any electrical equipment have a legal obligation to ensure

that it is safe when properly used. Provided that the correct fuse has beenfitted, commercial equipment should be safe without modification. However,instructions given by the manufacturer should be brought to the attention ofall users.

A.2.2 When older equipment is brought into use, arrangements must be made toensure that it conforms with current safety standards, and that its condition issuch that the original built-in safety has not been degraded by wear or misuse.It is the Department's responsibility to check that such equipment is safe touse and in case of doubt, reference should be made to the UniversityMaintenance Section.

A.2.3 This also applies when equipment has been out of the Department on loan orotherwise. Before being put back into use the Department must ensure that itis in a safe condition.

A.2.4 Equipment to be used out of doors should be fitted with a residual currentdevice (RCD) to provide optimum protection. In such cases, advice isavailable from the University Engineer. It should be noted, however, that theuse of RCDs cannot be regarded as replacing primary safety features(enclosure, insulation, etc.).

A.2.5 Particular attention is drawn to the high standards of maintenanceneeded in respect of 'hard use' electrical appliances. Visual checks ofplugs, power cables, connections (at plug and appliance ends) should be

frequently carried out and users instructed as to action to be taken if and

when unsafe conditions are identified. The term 'hard use' could include:

Vacuum cleaners

Floor scrubbers/polishers

Horticultural/gardening equipmentMains powered radios/tape players

Video recorders

Other AV equipment (especially if hired/loaned)Hand-held power toolsExtension leads

Floor/desk/table/inspection lamps


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Portable kitchen appliances

Heating mantles

Stirrers

Soldering irons

and most other equipment which is frequently moved about, plugged and

unplugged, or which is subject to added stresses from handling, wet, heat

or corrosion.

A.3 MAINTENANCE

A.3.1 It is the Department's responsibility to ensure that its electrical equipment ismaintained in a safe condition and that the condition of all appliances is keptunder review so as to prevent danger.

A.3.2 The most important arrangement to be made is a visual check of the conditionof the connecting cables and of the plug. The connecting cable must beundamaged and securely fastened both at the appliance end and at the plugends. The plug must be undamaged and must not rattle, which may indicate

loose terminals and potential danger. Check for visual evidence (blackening,scorching, etc.) of arcing or overheating. Any apparent defect must beinvestigated and remedial action taken.

A.3.3 A full electrical test must be undertaken from time to time. The frequency oftests depends on the amount, type and conditions of use. A good guide iscontained in the HSE leaflet, Maintaining Portable Electrical Equipment inOffices. Records of the test should be kept by the Department, preferably in aregister and on the equipment itself by means of a securely attached label, sothat the test history can be checked. Such tests should also form part of anyrepair procedures. (It should be noted that many service contracts will be

concerned only with the correct functioning of the equipment and not with itselectrical safety).

A.3.4 The University Engineer is prepared to carry out tests on behalf ofDepartments with small amounts of electrical equipment who do not havequalified staff available. This will be done at the Department's expense andarrangements should be made directly with the University Engineer's office.

A.3.5 Where equipment is shared by Departments, or is present in accommodationshared by Departments, specific arrangements must be made to ensure that theequipment is checked regularly.

A.4 SUMMARY

A.4.1 Users should be instructed in the safe methods of use of electrical equipmentand should be warned of the hazards of using unsafe equipment.

A.4.2 They should be made aware of the need to make frequent visual checks of thecondition of cables and plugs.

A.4.3 Departments should ensure that electrical equipment is safe to use wheninstalled and remains so by regular checking and maintenance at appropriate

intervals. Departments may choose to sub-contract such maintenance but itremains their responsibility to initiate and monitor any arrangement.


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PART B

B.1 SCOPE OF THIS PART OF THE CODE

B.1.1 This part is applicable to Departments having technical staff competent

to make inspections and carry out routine safety checks on electricalequipment.

B.1.2 It does not deal with the precautions to be taken when undertaking repair andtesting of electrical apparatus, or experimental work with electricalequipment. (For this see Part C).

Relevant guidance is included in:

Guidance Note IND(G)236L Maintaining portable electrical equipment inoffices

IEE Guidance Code of Practice for In-Service Inspection andTesting of Electrical Equipment

B.1.3 Electrical systems in buildings up to and including socket outlets (or in thecase of permanently installed equipment associated isolators) are normally theresponsibility of the Estates Office. Substations housing distributiontransformers and switchgear, including cabling and wiring, are theresponsibility of the University Engineer. No modification or adaptation may

be carried out except through his office.

B.1.4 Departments and sections are normally responsible for installations and

equipment from the socket (or isolator) outwards. Where there is anexception to this rule it must be defined in a formal agreement between theHead of Department or section and the University Engineer. It is particularlyimportant that when Departmental equipment is installed by a contractor, thecontract must make it clear where responsibility for electrical safety lies.

B.1.5 The University Engineer should be notified in advance of the acquisition ofany equipment requiring significant amounts of power, to ensure that thenecessary supply is available.

B.2 ELECTRICAL APPARATUS

B.2.1 Where standard commercial equipment is in use the primary requirement is

that there should be no access to dangerous voltages, i.e. those exceeding 50volts AC and 120 volts DC. If normal methods of working are adopted thisshould automatically follow from the standards of construction incorporated

by the manufacturer.

B.2.2 The same standards of safety must apply to electrical apparatus constructedwithin the University. Prototype equipment must conform in all respects withacceptable standards of electrical safety.

B.2.3 A list of minimum manufacturing safety standards is given in Section B.9.Before putting into use any electrical equipment, especially apparatusconstructed within the University, Departments should check that it conformsfully to these standards.


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B.3 MAINTENANCE

B.3.1 The University's responsibility to undertake regular checking of all electricalwiring up to the socket outlets or isolators will be carried out on a regular

planned basis by the Estates Office.

It is the Department's responsibility to deal with the safety of all electrical

equipment in use in the Department.

B.3.2 Heads of Departments should arrange for a simple visual check ofDepartmental electrical equipment to be carried out frequently by all users.The connecting cable should be undamaged and securely fastened both at theappliance end and at the plug ends. The plug should be undamaged and notrattle, which could indicate loose terminals and potential danger. Any defectsfound must be rectified forthwith.

B.3.3 Heads of Departments should also arrange for more thorough maintenanceand testing at regular intervals of all electrical appliances in use within the

Department. The arrangements must be set down in writing in theDepartmental Safety Handbook and/or Laboratory Safety Manual asappropriate. The frequency of tests will depend on the amount and type ofuse, and Departments with a substantial inventory of equipment mustdetermine their own programme based on their judgement of which equipmentshould be given priority and on the resources available.

B.3.4 It is recommended that Departments with suitably qualified personnel shouldcarry out the tests themselves using the schedule in Section B.7 as a guide.The University Engineer may be able to give further guidance to appropriate

personnel from the Department and will also give advice on appropriate

testing instruments for Departmental use.

B.3.5 For personnel within Departments carrying out testing of their electricalequipment, the following guidelines apply:

(i) The person given the task of carrying out the checks must becompetent to carry out the work and specifically, should have beeninstructed in the correct use of the instruments provided.

(ii) The results of all tests should be entered into a logbook (or on to aloose sheet, which is subsequently filed in a central register in the

Department). In addition, it is desirable to have a system of attachinga label to each item of equipment tested, identifying it, and the date ofthe most recent satisfactory test. Such records will provide evidenceof compliance with the Regulations and with accepted safe working

practice.

(iii) The information in the test record should include:

Description and identification of the piece of equipment being tested.

Nature of the test being carried out (as prescribed by the Department)

Date of test. Name of tester.

Whether the test was satisfactory.


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(iv) Note that in completing a record of this type, the tester is merelyrecording that he/she has carried out the test properly and inaccordance with the prescribed method and that there was a given

result (satisfactory or unsatisfactory). He/she is not certifying that

the equipment is safe to use or will remain so, and hence bears no

personal responsibility for any unsafe condition which may

subsequently arise.

B.4 USE OF ELECTRICAL EQUIPMENT IN LABORATORIES AND

WORKSHOPS

B.4.1 There are special hazards in the use of electrical equipment in laboratories andworkshops in that the equipment may be used in less than ideal conditions.

B.4.2 Particular problems arise when electrical equipment is used in the vicinity ofwater or other conducting fluids. Care must be taken to ensure adequate

segregation and protection to avoid fluids coming into contact with anyelectrical equipment.

B.4.3 When electricity is used for heating, for example in furnaces, problems mayarise due to deterioration of the supply cables near to heat sources and suitablehigh temperature insulated cables or thermal shielding must be provided.

B.4.4 In work places where flammable vapours may be present, care must be takento avoid electrical sparking leading to ignition. Where necessary, specially

protected apparatus must be used. See Dangerous Substances and ExplosiveAtmospheres Regulations 2002 S1 2002/2776.

B.4.5 Supply cables should be properly protected from mechanical damage (cuts,abrasions, etc.). It is good practice to arrange for each piece of apparatus to

be connected to its own individual socket outlet with as short a lead as possible. The use of multi-way sockets, extension leads and trailing cablesshould be avoided.

B.4.6 Hand-held lamps or lamps used in connection with workshop machinery are particularly vulnerable to damage and rapid wear. They should be adequately protected and in addition, should be fed from a low voltage (max. 25v)supply.

(Other hazards may arise when equipment is being repaired or constructed andthese are discussed in Part C).

B.5 BATTERIES

B.5.1 High current sources such as secondary batteries present special problems.Wherever possible they should be protected by fuses or circuit breakers asclose as possible to the source.

B.5.2 Wherever possible batteries should be covered, so that short-circuits will not be caused by objects falling across the terminals.

B.5.3 Rings must never be worn when working with unprotected high currentsources. Even quite small nickel-cadmium cells have been known to produceenough current to sever a finger when short-circuited by a metal ring.


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B.5.4 Rechargeable wet batteries must be used only in well-ventilated areas. Duringrecharging an explosive mixture of hydrogen and oxygen is evolved which iseasily ignited. Warning notices conforming to the appropriate BritishStandard should be displayed in all battery charging areas.

(Problems have arisen in testing the state of charge of batteries of this type.Use of a voltage drop method has been known to cause a spark leading to anexplosion. The preferred method is to measure the specific gravity of the acid

with a hydrometer).

B.5.5 When connecting and disconnecting batteries, great care should be taken to prevent arcing or sparking at the battery terminals by making and breaking thecircuit away from the immediate vicinity of the battery.

B.6 CONNECTION OF ELECTRICAL EQUIPMENT TO HUMAN BEINGS

B.6.1 There are particular dangers in procedures where human beings are connectedto electrical recording and/or stimulating apparatus.

B.6.2 There are not only those dangers which are inherent in the equipment itself but those of unforeseen earth paths being created by the subject touching otherelectrical apparatus, sockets, conduits and other conductive material in thevicinity.

B.6.3 When humans are deliberately brought into contact with electricity, the

greatest care is needed to ensure that the equipment used and the systems

of work adopted are of the highest standard and kept under constantreview. This review should include a positive check on the relevant

British Standards to ensure that developments in equipment safety and

safe systems of work are progressively incorporated. Procedures must be

fully documented and brought to the attention of all who need to know.All those involved in such procedures should be aware of the risks

attached, particularly that of fatal electric shock, and of the action to be

taken in emergency. If this is part of a study then ethical approval will be

required.

B.6.4 There is comprehensive information on the categories and use of suchequipment in BS 5724 and this has been abstracted in J. Biomed. Eng. 1982Vol. 4, July, pp 185-196.

B.7 ROUTINE CHECKS OF ELECTRICAL EQUIPMENT

Visual Checks:

B.7.1 there is no access to live parts;

B.7.2 there is no obvious mechanical damage to the equipment, cable or plug;

B.7.3 the cable grip is still gripping both the inner conductors and the outer protection of the cable;

B.7.4 any extra protective device around the cable where it enters the equipment is

undamaged and in position;

B.7.5 the cable does not pass through any openings with unprotected sharp edges;


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Electrical Checks

B.7.6 the electrical connections between cable and plug are firmly and correctlymade, and where applicable, a correctly rated fuse has been fitted;

B.7.7 the earth continuity is satisfactory;

B.7.8 insulation resistance is adequate;

B.7.9 earth leakage tests are satisfactory. (NOTE that special testing procedures arenecessary on double-insulated [Class II] appliances marked with the symbol

.ALSO that special equipment is necessary for appliances with a capacitoracross the mains input. Details of the standard tests are given in BS 2754Construction of electrical equipment for protection against electrical shockand further advice may be obtained from the University Engineer.

B.8 MINIMUM MANUFACTURING STANDARDS

B.8.1 The following list of minimum manufacturing standards is based on BritishStandard specification BS EN 60335:2002 Safety of household and similarelectrical appliances.

B.8.2 Before taking any electrical equipment into service (especially apparatusconstructed within the University), the Department should check that itcomplies with these requirements.

B.8.3 All accessible metal parts of electrical machines should be efficiently earthed.

B.8.4 All flexible cords, plugs, sockets and connectors should be of good qualityand standard. Flexible cables need to be adequately sized, constructed and protected, with proper connections and colour coding.

B.8.5 Mains input switches should be suitably placed on the machines, and the "On"and "Off" positions properly identified and accessible.

B.8.6 All phases should be disconnected by the operation of the switch.

B.8.7 An effective over-current protection device (e.g. a fuse) should be provided ineach phase of the circuit and arranged so as to disconnect the electricity

supply to the equipment in the event of overload or short circuit.

B.8.8 If the supply to the equipment is made through an isolator, provision should be made for securing the isolator switch against inadvertent and unauthorisedoperation, e.g. by use of padlocks. All live terminals should be effectivelyscreened. Note particularly that if it is necessary for an operator to haveaccess to particular parts of the interior of the machine, this should not allowaccess to live electrical parts at the same time.

B.8.9 If this is achieved by provision of guards with interlock switches, the switchesshould be of such design and construction as to prohibit deliberate overriding

or inadvertent operation, (see for example BS EN 60204-1:2006 Safety ofmachinery. Electrical equipment of machines. General requirements. providesrequirements and recommendations) standard and frequency of maintenanceand testing is all important in such circumstances.

B.8.10 All live conductors and terminals carrying dangerous voltages should be

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securely screened and a suitable warning notice indicating the danger placedin a prominent position.

B.8.11 If heating elements are used in any equipment they should be placed andinstalled so as to cause no deterioration of electrical equipment or overheatingthat would result in hazard to persons or plant.

B.8.12 If fluids, except for transformer oils and the like, are used in any equipment,

they should be used and housed so that they do not come into contact withelectrical conductors and components. Where the incorporation of conductingof any other fluids into equipment is necessary, the design should, wherever

possible, place such fluids at the lowest level possible. Any accidental releaseof fluids will, therefore, tend to cause the least danger. In the case offlammable fluids, special attention should be given to the machine enclosureto prevent dangerous concentration of vapour.

B.8.13 All electrical conductors and components should be housed or constructed soas to avoid risk of fire or explosion, e.g. by the use of certified equipment orother equally effective measures.

B.8.14 Applicable Legislation

The Electrical Equipment (Safety) Regulations 1994 SI 1994/3260Electromagnetic Compatibility Regulations 1992 SI 1992/2372


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PART C

This part is designed for use in Departments where workers may need to have access to

potentially hazardous voltages as a necessary part of their work and are specifically

authorised to do so. Examples of situations in which this can occur are where fault

diagnosis or repair are necessary, covers or panels are removed from electricalequipment and this results in access to hazardous voltages. A related situation is where

an experimental rig is being built up and there is access to hazardous voltages at

intermediate stages of construction.

Relevant HSE guidance is included in:Guidance Note GS 38 - Electrical test equipment for use by electricians

C.1 METHODS OF WORKING

C.1.1 The first priority is to protect all persons who are not associated with the

equipment or test. The aim should be to prevent all such persons from havingaccess to the dangerous voltages. This may be done by segregation, lockingthe work area to outsiders, by having an electrically-interlocked system so thataccess to the segregated area automatically disconnects the supply or, if anyor all of these are not available, by prominent warning notices. The method(s)chosen will depend on an assessment of the likely hazard.

C.1.2 The next important point is to consider the methods of protection of theoperators. All operators should be trained to understand the hazards of thevoltages involved and to be aware of the location of the hazardous regions inthe particular equipment in use.

C.1.3 In assessing any situation for possible hazards, the knowledge and experienceof the operators should obviously be taken into account, but must not be reliedon as the sole or main means of securing safe conditions. It must be borne inmind that even the most experienced operator may accidentally touch anexposed high voltage point because of a slip or fall or by being momentarilydistracted. If the conditions are unfavourable such a momentary lapse couldresult in death or severe injury.

C.1.4 Layout of the working area is very important. If dangerous voltages arenecessarily exposed the apparatus or the bench on which it is supported

should be surrounded by a clear and unobstructed zone and should be wellclear of any adjacent benches or apparatus. This will minimise the risk ofanyone inadvertently falling and touching a live conductor and of accidentalcontact between adjacent operators or equipment.

C.2 ENTRY TO PREMISES

C.2.1. Entry into any laboratory in which live conductors at voltages above 50 voltsAC and 120 volts DC have to be exposed should be restricted to personnelwho have been given specific permission in writing by the person in charge ofthe laboratory.

C.2.2 Under normal circumstances when dangerous voltages are necessarilyexposed, authorised persons should be in continuous attendance. Inexceptional circumstances where a lengthy test necessitates a live system


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being left unattended, the area should be protected by barriers to preventunauthorised or inadvertent access. In any case, the laboratory should belocked, and keys available only to authorised persons.

C.3 EMERGENCY ARRANGEMENTS

C.3.1 Having carried out the systematic risk assessment advocated in Section C.1(Methods of Work) a 'worst typical' situation should then be assumed, on

which appropriate arrangements for use in an emergency can be based.Amongst other things, these will need to consider:

- Sources of assistance in case of electric shock and fire.

- Adequate means of raising the alarm.

- Access for and the safety of first aiders, firefighters, police, ambulancecrews.

- Location of power cut-off devices (See Section C.6 Residual current

devices).

- Location of insulating footwear, gloves, tools, etc.

- Evacuation routes.

C.3.2 Wherever possible, emergency stop buttons should be fitted so that allelectrical supplies (except for lighting) can be cut off in an emergency. Theseshould be clearly marked. In areas with potentially high risks, persons shouldonly work with another person within sight and sound. All persons should beaware of the emergency procedures and should be able quickly and safely to

isolate the electrical supply, summon help and to start resuscitation treatmentwhere necessary.

C.3.3 Instructions on the treatment of persons suffering from electric shock must be prominently displayed in all places where voltages above 50 volts AC or 120volts DC are in use.

C.4 REPAIRS

C.4.1 During repairs, protective covers may have to be removed thereby exposinglive parts.

C.4.2 In these circumstances the hazard to be avoided is that of making a circuitfrom the high voltage conductor to another conductor or to earth via thehuman body, with risk of fatal injury.

C.4.3 This type of work should not be carried out in remote areas away from otherworkers who could give assistance in an emergency. (See C.3).

C.4.4 Electrical systems may involve a mains transformer, which reduces thevoltages in the secondary to values less than 50 volts AC. In such a systemthe main risk will therefore be on the connections to the input to the primary.

Equipment should always be examined before use and further protectiongiven to any exposed terminals in the circuit to minimise the risk. However,there will always be a residual risk.


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C.4.5 The risks of a high voltage path to earth can be reduced by creating an earth-free area in which, as far as possible, all potential earth pathways are removedand an earth leakage protection device has been fitted or by using deviceswhich will prevent the passage of earth fault current or limit the current to

below 5mA. (See also Section C.6).

C.5 EARTH-FREE AREAS

C.5.1 Advice on the setting up of such areas is given in the HSE booklet IND(G)354 – Safety in Electrical Testing at Work. The test bench, which should beconstructed of insulating material, must be screened from metal-casedswitches and plugs, conduit, radiators, heaters, window frames, water pipesand taps etc. Rubber mats to British Standard 921/1976 should be provided ifthe floor insulation cannot be relied on, and these must be kept in good repairand tested at intervals.

C.5.2 An isolating transformer complying with BS 61558 having an unearthedsecondary of 240 volts should be used as a "mains" supply inside the area, thetransformer being situated outside the area.

C.5.3 Soldering irons and lamps be operated from a separate unearthed 24 voltsupply or be of the rechargeable battery type.

C.5.4 The area should preferably, be screened off by insulating barriers, and onlyone person at a time may be permitted in the earth-free area. No externalsignals should be brought into or transmitted from the area unless suitablyisolated from normal mains and earth, e.g. by signal isolation amplifiers orsignal isolation buffers, with an isolation of at least 1000v pk-to-pk.

C.6 RESIDUAL CURRENT DEVICES (RCDs) FOR EARTH LEAKAGE

PROTECTION

C.6.1 Residual current devices (previously ELCBs/RCCBs) monitor the current inthe live and neutral conductors any imbalance will cause the device to trip.

C.6.2 RCDs can be installed in an electrical circuit as a protective device, whichwill rapidly disconnect the mains supply if a fault current is detected. Themagnitude of the fault current allowed is preset and in circumstances whereshock to persons is anticipated this should be between 10mA and 30mA andtrip the supply within 30mS. This limits the energy, which may be passedthrough the body. RCDs for protection against fire may have a preset

sensitivity of up to 100mA. RCDs will not protect a person touching both liveand neutral conductors.

C.6.3 The IEE Regulations state that all installations outside the equipotential zone,

i.e. external/outdoor from the main installation should be protected by RCDs.The Regulations make it clear, however, that reliance on this form of

protection is not acceptable as the sole or main means of protecting personsfrom electric shock. RCDs may only be used as a useful backup to primarysafeguards such as insulation, enclosure, low voltage etc.

C.7 REPAIRS IN THE FIELD

C.7.1 With bulky apparatus it may be necessary to undertake repairs on the spotaway from specially equipped testing facilities. Under these circumstances,


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operators must be especially aware of the potential risks and means ofavoiding danger. Valuable protection can be given to persons carrying outelectrical tests by providing them with a portable residual current deviceconnected by a short cable to a multiple way socket block. All RCDs should

be tested frequently by means of the inbuilt "test button" and also tested forcurrent and time limits. When selecting RCDs care should be taken to ensurethat they are suitable for use with equipment, which may produce a DCcomponent on the supply, with the possibility of desensitising the RCD.

C.8 EXPERIMENTAL EQUIPMENT (See also B.2)

C.8.1 All rigs and temporary wiring should be constructed so as to conform fully torecognised electrical safety standards with regard to the strength andcapability of conductors, insulation, connections, earthing, over-current

protection, switching, isolation, access and all other aspects having a bearingon the safety of persons and equipment. "Temporary" is all too often used asan excuse for unsafe constructional standards and inadequate safety

precautions.

C.8.2 Equipment should be constructed, wired and maintained to the standardrequired for portable electrical equipment in general use. (See BS 2754).

C.8.3 Safety standards must not be relaxed because the equipment is undergoingdevelopment. The temptation to retain temporary arrangements once theexperimental technique has been established must be firmly resisted. At that

point every effort must be made to make the system as safe as possible."Temporary" arrangements may by default last for long periods, sometimesafter the constructor has left the University, and this results in potential dangerto future users. Similarly, a comprehensive circuit diagram should always bemade available and kept with the equipment. Details of modifications to

standard equipment should also be fully documented.

C.8.4 Protection against electric shock should be incorporated as soon as possible.Prior to that stage, appropriate warning notices should be displayed givinginformation and warning of temporary hazards.

C.8.5 It is strongly recommended that control gear associated with 415v 3-phaseequipment should be operated at 110v AC from a 55-0-55v supply with anearthed centre point.

C.9 ADDITIONAL REQUIREMENTS FOR DISTRIBUTION TO RESEARCH OR

EXPERIMENTAL APPARATUS SUPPLIED AT, OR GENERATING,VOLTAGES ABOVE 650 VOLTS AC AND DC

C.9.1 All apparatus on which conductors may be exposed when live at a voltageabove 650 should be placed in a segregated enclosure so as to prevent danger.

C.9.2 Arrangements should be such that the enclosure cannot be entered unless thesupply has been made dead and earthed either by the use of a door operatedlimit switch supplemented by a door operated gravity earth or by theinterlocking of the door with a supply circuit breaker using figured keyinterlocks. Additionally, a portable earthing rod should be provided within

the enclosure, and applied to exposed conductors before contact with them ismade. This restriction does not normally apply to non-lethal high voltagesystems where the current availability is below 5mA.


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APPENDIX 1

HSE and HSC publications on electrical safety

Guidance Note Title

Regulations particularlyrelevant

PM 29 Electrical hazards from steam/water pressure cleanersISBN 0 7176 0813 1

4, 6, 7, 8, 10

PM 38 Selection and use of electric handlampsISBN 0 11 886360 6

4, 6, 7, 8, 10, 12

GS 6 Avoidance of danger from overhead electric linesISBN 0 7176 1348 8

4, 14, 15, 16

GS 38 Electrical test equipment for use by electriciansISBN 0 7176 0845 X

10, 14, 16

GS 50 Electrical safety at places of entertainmentISBN 0 7176 1387 9

4, 5, 6, 7, 8, 10,11, 12

HSG 38 Lighting at work:ISBN 0 7176 1232 5

4, 13, 14, 15

HSG 47 Avoiding danger from underground servicesISBN 0 7176 1744 0

4, 14, 16

HSG 85 Electricity at work - safe working practicesISBN 0 7176 2164 2

4, 7, 12, 13, 14,15, 16

HSG 118 Electrical safety in arc weldingISBN 0 7176 0704 6

4, 6, 7, 8, 10, 12,14, 16

HSG 141 Electrical safety on construction sitesISBN 0 7176 1000 4

4 - 16 inclusive

HSG 230 Keeping electrical switchgear safe

ISBN 0 7176 2359 9

4, 5, 6, 11, 12

INDG 231 Electrical safety and youISBN 0 7176 1207 4

4 - 16 inclusive

INDG 236 Maintaining portable electrical equipment in officesISBN 0 7176 1272 4

NOTE: The publications listed in Appendix 1 are available from HSE Books


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APPENDIX 2

Other publications having an electrical safety content

Standards, Codes of Practice and other publications, which contain guidance relevant to theRegulations and electrical safety, which have been published by bodies other than either HSEor HSC, are given in this appendix. Most of these documents are the product of technicalcommittees on which HSE has been represented. This does not mean, however, that the

documents are concerned solely with safety and users should bear in mind the scope of thesafety content of these documents and the fact that they have largely been arrived at througha process of consensus.

Note: British Standards Institution publications are obtainable from BSI Sales and CustomerServices, 389 Chiswick High Road, London W4 4AL. Tel: 0181 996 7000. Fax: 0181 9967001.

Title of PublicationPrincipalregulationsrelevant

Comments

(BS = British Standard)

International Electrotechnical CommissionPublication 479. Effects of current passingthrough the human body. Parts I and II.Also published as BS PD 6519 Pts 1 and 2.

2 Definition of 'danger' and'injury' - electric shock

International Electrotechnical CommissionGuide 105. Principles concerning the safetyof equipment electrically connected to atelecommunications network.

2 Ditto - on telecommuncationsystems

IEC 1201:1992 Extra-low Voltage (ELV)limit values. Also published asBS PD 6536:1992

2 Electric shock - sets out limitvalues

BS 7671: 2001 Requirements for ElectricalInstallations (IEE Wiring RegulationsSixteenth edition) (obtainable from the IEE,PO Box 96, Stevenage, Herts, SG1 2SD).

4(15-12inclusive

Selection of equipment andconstruction of installations upto 1000 volts AC.

BS 4363:1968. Specification for

distribution units for electricity supplies forconstruction and building sites.

4, 6, 10

BS 7375:1991 Distribution of electricity onconstruction and building sites.

4, 6, 10

BS 5486 Pt 1:1990 (up to 1000 V ac and1200 V dc) BS 5227:1984 (above 1000 V acand 1200 V dc).

4, 5, 12, 15 Particular attention forswitchgear clearancedistances. Safety clearancesand work sections.

BS 6423:1983 Code of practice for 4(2), 4(3), Precautions to secure safety of


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maintenance of electrical switchgear andcontrol gear for voltages up to and including650 V.

12, 13 maintenance, personnelisolation procedures

BS 6626:1985 Code of practice formaintenance of electrical switchgear andcontrol gear for voltages above 650 V andup to and including 36 kV.

4(2), 4(3),12, 13

Precautions to secure safety of personnel

BS 6867:1987 Code of practice formaintenance of electrical switchgear andcontrol gear for voltages above 36 kV.

4(2), 4(3),12, 13

Precautions to secure safety of personnel

BS EN 60204-1:1993 Electrical equipmentof machines. Specification for generalrequirements.

4, 6

BS 697:1986 Specification for rubbergloves for electrical purposes.

4(4), 14

BS 921:1976 (1987) Specification. Rubbermats for electrical purposes.

4(4), 14 Mats for covering floor nearelectrical equipment wheredirect contact may occur

BS 5490:1977 (1985) Specification forclassification of degrees of protection

provided by enclosures.

6, 7 Index of protection (IP)system against contact withlive and moving parts andingress of solids and moistureand finger test

BS 5420:1977 Specification for degrees of protection of enclosures of switchgear and

control gear for voltages up to and including1000 V ac and 1200 V dc.

6, 7 Index of protection (IP)system against contact with

live and moving parts andingress of solids and moistureand finger test

BS 4999 Part 20:1972 General requirementsfor rotating electrical machines.Classification of types of enclosure.

6, 7 Index of Protection (IP)system against contact withlive and moving parts andingress of solids and moisture

BS 5345 Code of practice for selection,installation and maintenance of electricalapparatus for use in potentially explosive

atmospheres (other than mining applicationsor explosive processing and manufacture).

4(1), 4(2), 6 See also HSE booklet HSG22(Appendix 1)

BS 5501 Electrical apparatus for potentiallyexplosive atmospheres.

4(1), 6 See also HSE booklet HSG22(Appendix 1)

BS CP 1003 Electrical apparatus andassociated equipment for use in explosiveatmospheres of gas or vapour other thanmining applications (obsolescent, replaced

by Parts 1 to 8 of BS 5345 but retained as areference guide).

4(1), 4(2), 6 See also HSE booklet HSG22(Appendix 1)


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BS 6742 Part 1:1987 Electrostatic paintingand finishing equipment using flammablematerials specification for hand-held sprayguns and associated apparatus.

6 Protection against ignition

BS 6467:Part 1:1985 Electrical apparatuswith protection by enclosure for use in the

presence of combustible dusts.

Specification for apparatus.

6 Protection against ignition

BS 6467:Part 2:1988 Guide to selection,installation and maintenance.

4, 5, 6 Protection against ignition

BS 6651:1992 Code of practice for protection of structures against lightning.

6 As relevant to protection ofelectrical equipment fromlightning.

BS 5958:1991 Code of practice for controlof undesirable static electricity.

6 Precautions against ignitionand electric shock

BS 4444:1969 (1980) Guide to electricalearth monitoring.

8

BS 7430:1991 Earthing 8

BS 5419:1977 (1990) Specification for air break switches, air break disconnectors andfuse-combination units for voltages up toand including 1000 V ac and 1200 V dc.

12

BS 2754:1976 Memorandum Constructionof electrical equipment for protectionagainst electric shock.

7, 8

BS 5655:Part 1:1986 Safety rules for theconstruction and installation of electric lifts.

15 Clear areas in front of electricequipment specified (Clause6.3.2.1)

BS 5253:1990 Specification for ACdisconnectors and earthing switches. To beread in conjunction with BS 6581:1985

12

Code of Practice for In-Service Inspectionand Testing of Electrical EquipmentISBN 0 85296 776 4

BS EN 60204-1:2006 Safety of machinery.Electrical equipment of machines. Generalrequirements


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APPENDIX 3

Working space and access; historical comment on revoked legislation

(see regulation 15)

Among the legal provisions revoked upon the coming into force of the Electricity at WorkRegulations 1989 were the Electricity (Factories Act) Special Regulations 1908 and 1944.Regulation 17 of those Regulations specified minimum width and height dimensions of

'switchboard passage-ways' if there were 'bare conductors' exposed or arranged to be exposedwhen 'live' so that they may be touched. These related to what are commonly known as 'opentype' switchboards, which had much exposed copper work, knife switches etc. Thatregulation (and the key definitions used at that time) is reproduced below for information.The dimensions, which were specified by that regulation were arrived at after muchconsideration of the circumstances at the time. A compromise was struck between theobjective of achieving the safety of those who had to work at and operate these 'open type'switchboards and the need to recognise the constraints imposed by the installations existingand the nature of the technology in 1908. Even though the dimensions were a compromise itwas widely recognised that they were a good minimum standard which had been foundnecessary following a number of severe and fatal accidents in factories and power stations

due to inadequate space or cluttered access in the vicinity of bare live conductors at these'open type' switchboards. The dimensions chosen allowed workmen to operate or otherwisework upon the switchboard in reasonable safety and allowed, for example, persons to passone another in the switchboard passageway without being placed at unacceptable risk oftouching live conductors.

Where the need does arise to work on or near live conductors, the principles of providingadequate working space and uncluttered access/egress, which were expressed in regulation17 of the Electricity (Factories Act) Special Regulations 1908 and 1944, should be given

proper consideration.

Regulation 17 (of 1908 Regulations)

At the working platform of every switchboard and in every switchboard passageway, if there be bare conductors exposed or arranged to be exposed when live so that they may betouched, there shall be a clear and unobstructed passage of ample width and height, with afirm and even floor. Adequate means of access, free from danger, shall be provided forevery switchboard passageway.

The following provisions shall apply to all such switchboard working platforms and passage-ways constructed after January 1, 1909 unless the bare conductors, whether overhead or atthe sides of the passageways, are otherwise adequately protected against danger by divisions

or screens or other suitable means:

(a) Those constructed for low pressure and medium pressure switchboards shall have a clearheight of not less than 7 ft and a clear width measured from bare conductor of not lessthan 3 ft.

(b) Those constructed for high pressure and extra high pressure switchboards, other thanoperating desks or panels working solely at low pressure, shall have a clear height of notless than 8 ft and a clear width measured from bare conductor of not less than 3 ft 6 in.

(c) Bare conductors shall not be exposed on both sides of the switchboard passageway unless

either (i) the clear width of the passage is in the case of low pressure and medium pressure not less than 4 ft 6 in and in the case of high pressure and extra high pressure notless than 8 ft in each case measured between bare conductors, or (ii) the conductors onone side are so guarded that they cannot be accidentally touched.


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Key definitions used in the 1908 regulations

Switchboard means the collection of switches or fuses, conductors, and other apparatus inconnection therewith, used for the purpose of controlling the current or pressure in anysystem or part of a system.

Switchboard passageway means any passage-way or compartment large enough for a person

to enter, and used in connection with a switchboard when live.

Low pressure means a pressure in a system normally not exceeding 250 volts where theelectrical energy is used.

Medium pressure means a pressure in a system normally above 250 volts, but not exceeding650 volts, where the electrical energy is used.

High pressure means a pressure in a system normally above 650 volts, but not exceeding3000 volts, where the electrical energy is used or supplied.

Extra-high pressure means a pressure in a system normally exceeding 3000 volts where theelectrical energy is used or supplied.


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APPENDIX 4

UNIVERSITY OF LEICESTER


GUIDE TO THE ELECTRICITY AT WORK REGULATIONS 1989(SI 1989 NO. 635)

INTRODUCTION

1.

As the Foreword to the Code of Practice points out, the statutory requirementsrelating to electricity at work are contained in the Regulations. The best currentlyavailable source of information on the Regulations and their interpretation iscontained in a publication from the Health and Safety Executive under the title:

Memorandum of Guidance on the Electricity at Work Regulations HS(R)25 ISBN0717616029 (HMSO £4.00 net).

2. Copies are readily available from the University's Bookshop and Departments havinga substantial inventory of electrical equipment and/or who will be involved in routine

electrical testing as required by the University Code of Practice are strongly advisedto obtain a copy. The publication will be particularly important and useful to thoseDepartments affected by Parts B and C of the Code (See Introduction, Section 1.3

p3).

3. As a means of ready reference, however, this Appendix summarises the text of eachRegulation with a brief note on its implications, cross-referenced to the relevantSection(s) of the University Code.


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ELECTRICITY AT WORK REGULATIONS 1989

Regulation 1

(Citation and commencement) is procedural only.

Regulation 2

Gives important interpretations of terms used in the various sections. 'Injury' for example, isdefined as death or injury to persons from:

(a) electric shock;(b) burns caused by electricity;(c) fires having an electrical cause;(d) electric arcing;(e) explosions initiated or caused by electricity.

'Danger' is defined as the risk of injury.

Comment: These terms occur frequently throughout the Regulations. It is thereforeimportant to know what it is that the Regulations are designed to do, as wellas to be aware of their limitations. Some of the Regulations, for example, arequalified by the phrase 'so far as is reasonably practicable', which means thatthe 'danger' as defined has to be balanced against the time, trouble,inconvenience and funds that would be needed to obviate or substantiallyreduce such danger. This qualification applies to Regulations:

4(1) Construction of electrical systems.4(2) Maintenance (including testing) of systems.

4(3) Conduct or work activities on electrical systems.6. Electrical systems in adverse conditions (mechanical damage, weather, wet,

flammable or explosive environments etc.)7. Insulation, protection and placing of conductors.

A Regulation, which is qualified by the phrase 'so far as is reasonably practicable' is not

elective, nor is it weakened in any way by the qualification. Indeed, in many instancesthe duty is more difficult to comply with since the risk assessment referred to above

must show clearly that the time, trouble, inconvenience and funds needed to obviate or

substantially reduce the danger are wholly excessive and out of balance and that

therefore it is not 'reasonably practicable' to follow or not a particular course of action.

The process of deciding whether or not a course of action is 'reasonably practicable'

can be likened to putting danger on one side of a scale and the time, trouble,

inconvenience and funds on the other. Where one side or the other is obviouslyoutweighed, the correct course of action is clear. When the 'scales' are in balance, or

when one side only marginally outweighs the other, the right decision becomes less

clear, requiring much more careful thought. In such cases, it becomes more important

that the risk assessment process should be fully documented as a defence in the event ofprosecution. (See below).

The rest of the Regulations are 'absolute' in nature and cannot be qualified. An absolute

requirement must be met regardless of cost or inconvenience. Those having authority andresponsibility under the Regulations ('duty holders' as they are termed) can, however, offerthe defence that they 'took all reasonable steps' and 'exercised all due diligence' to avoidcommitting an offence.


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Such a situation would only arise in the course of prosecutions, and whether the defencesucceeded or not would depend on the decision of the Court in the light of evidence

presented.

Regulation 3

Refers to duties and to persons on whom duties are placed by the Regulations.

Comment: The greater part of the statutory duties rest on the employer. However,employees also have duties; to co-operate with the employer for example, inmaintaining safe systems of work and - very importantly - to comply with theRegulations insofar as such compliance lies within their control. This latterrecognises the authority conferred by technical knowledge, skill and expertiseand the consequent responsibility which must be accepted by skilledemployees for their own and others safety in respect of electrical work.

(See also Regulation 16 on 'competence').

Regulation 4

4(1) requires that all electrical systems shall be of such construction as to prevent dangerso far as is reasonably practicable;

4(2) requires that all systems shall be maintained so as to prevent danger so far as isreasonably practicable (University Code B.3, B.7);

4(3) requires that operation, use and maintenance of an electrical system shall not so far asis reasonably practicable give rise to danger (University Code B.2);

4(4) states that 'any equipment provided under these Regulations for the purpose of

protecting persons at work on or near electrical equipment shall be suitable for the purpose for which it is provided, be maintained in a condition suitable for that useand be properly used'.

Comment: 'Protective equipment' is a wide-ranging term which includes the special tools,clothing, boots, gloves, screens, mats, benches etc. that may be necessary toenable electrical work to be carried on with safety. Note that this, like most ofthe Regulations, is absolute in recognition of the 'last-ditch' nature of, forexample, insulating gloves and mats. It is also worth noting the requirementthat, when such equipment is provided, it must be properly used byemployees.

Regulation 5

Requires that electrical equipment shall not be put into use in ways or under conditions inwhich its 'strength and capability' might be exceeded in such a way as to give rise to danger.

Comment: The term 'strength and capability' refers to the ability of the equipment towithstand the effects of electrical current which might be expected to flowthrough it when the equipment is part of a system. Those currents include, forexample, load currents, transient overloads, fault currents, pulses of currentand, for alternating current systems, currents at various power factors and

frequencies. Insulation must be effective to enable the equipment towithstand the applied voltages and any likely over-voltages.


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It is recommended that the equipment is used within the manufacturer's rating(continuous, intermittent or fault rating as appropriate) and in accordance withany accompanying instructions, operating manuals or accepted practice forsuch equipment.

Regulation 6

States that 'electrical equipment which may reasonably foreseeably be exposed to:

(a) mechanical damage;(b) the effects of the weather, natural hazards, temperature or pressure;(c) the effects of explosive substances, including dusts, vapours or gases, shall be of such

construction or as necessary protected as to prevent, so far as is reasonably practicable, danger arising from such exposure'.

Comment: The implications of the Regulation are of particular interest to Universities,where many of the conditions envisaged may be encountered. 'Mechanicaldamage' for example, could refer to the vacuum cleaner pulled along by its

supply cable. 'Effects of the weather' is relevant to the outdoor use of powertools. 'Explosive substances....vapours or gases' can be found in manydistillation/reduction processes.

Where such conditions are anticipated, the equipment must be constructedaccordingly by means of extra robustness, spark/flameproofing, isolation fromthe source of danger or whatever is appropriate in the circumstances.(University Code B.1, B.2, B.3, B.4).

Regulation 7

Refers to the 'insulation, protection and placing of conductors'.

7(a) States that 'all conductors in a system which may give rise to danger shall be suitablycovered with insulating material and as necessary protected so as to prevent, so far asis reasonably practicable, danger'.

Comment: 'Suitably covered' means insulated in ways that are appropriate to the kind ofservice the conductors are required to undertake. Temporary insulation, forexample in situations where adequate insulation is critical, would be a breachof the Regulation, as would routing an insulated conductor over a hot surfaceor a sharp edge. (University Code B.2, B.4, B.7).

Regulation 8

Requires precautions to be taken 'either by earthing or by other suitable means, to preventdanger arising when any conductor (other than a circuit conductor) which may reasonablyforeseeably become charged as the result of either the use of a system or a fault in a system,

becomes so charged and, for the purposes of ensuring compliance with this Regulation, aconductor shall be regarded as earthed when it is connected to the general mass of earth byconductors of strength and current-carrying capability to discharge electrical energy to earth'.

Comment: The length and wording of this Regulation reflect the central importance of

the subject to electrical safety. The HSE's Memorandum has close on threeA4 pages of detailed guidance on earthing and equivalent precautions, whichwill repay close study. (University Code B.3, B.4, B.6, B.8, C.4, C.5, C.7,C.8, C.9).


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Regulation 9

(Integrity of referenced conductors). The Regulation reads: 'If a circuit conductor isconnected to earth or to any other reference point, nothing which might reasonably beexpected to give rise to danger by breaking the electrical continuity or introducing highimpedance shall be placed in that conductor unless suitable precautions are taken to preventthe danger'.

Comment: The object of the Regulation is to prevent referenced circuit conductors whichshould be at or about the same potential as the reference point from reachingsignificantly different potentials thereby giving rise to possible danger.(There is the need, for example, in 3-phase systems, where the neutralconductor is connected to earth at the source of supply, to ensure that the

phase voltages match and are not affected by discrepancies in loading).(University Code B.2, B.8, C.5, C.8, C.9).

Regulation 10

Refers to electrical connections and states: 'Where necessary to prevent danger, every jointand connection in a system shall be mechanically and electrically suitable for use.'

Comment: The Regulation requires that all connections in a circuit and protectiveconductors (including connections to terminals, plugs and sockets and anyother means of joining or connecting conductors) must be suitable for theintended duty. It is true to say that, of the thousands who daily attach 3-pin13-amp plugs to equipment and appliances, only a minority understand theelectrical principles lying behind this apparently simple task. One of the mostfrequent causes of electrical fatalities is the malfunctioning of dangerouslyconnected plugs, with over-stripping, cross connection, and failure to securely

clamp circuit and protective conductors the most common faults.

Special attention should be given to joints and connections in cables andequipment, which will be handled, for example, flexible cables for portableequipment. Specific guidance is given in Appendices 1 and 2 and in theUniversity Code (A.2, A.3, B.2, B.3, B.4, B.6, B.7.3, B.8.10, C.8).

Regulation 11

Refers to the 'means for protecting from excess of current'. HSE guidance deals at lengthwith the various techniques for preventing danger and damage from over-current conditions.

Topics include:

(a) The need to anticipate abnormal conditions.(b) Selection of excess current protective devices.(c) The nature of the circuits and type of equipment to be protected.(d) The short circuit energy available in the supply (the fault level).(e) The nature of the environment.(f) Whether the system is earthed or not.

It is recognised that in conditions where excess current is drawn due to a fault or overload,(e.g. an arcing fault), it may be technically impossible to achieve e total compliance with the

'absolute' requirements. The defence of 'all due diligence/all practicable steps' is available insuch circumstances and the HSE's Memorandum gives examples of how this might bedemonstrated. (University Code A.1, A.3, B.2, B.5, B.7, B.8, C.8).


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Regulation 12

States:

(1) Subject to paragraph (3), where necessary to prevent danger, suitable means(including, where appropriate, methods of identifying circuits) shall be available for -

(a) cutting off the supply of electrical energy to any electrical equipment; and

(b) the isolation of any electrical equipment.

(2) In paragraph (1) 'isolation' means the disconnection and separation of the electricalequipment from every source of electrical energy in such a way that thisdisconnection and separation is secure.

(3) Paragraph (1) shall not apply to electrical equipment which is itself a source ofelectrical energy but, in such case as is necessary, precautions should be taken to

prevent, so far as is reasonably practicable, danger.

The HSE Memorandum amplifies the important distinction between 'switching off' and'isolation'.

Regulation 12(1)(a)

2 The objective is to ensure that, where necessary to prevent danger, suitable means areavailable by which the electricity supply to any piece of equipment can be switched off.Switching can be for example by direct manual operation or by indirect operation via 'stop'

buttons in the control circuit of contactors or circuit breakers.

Regulation 12(1)(b)

3 Whereas regulation 12(1)(a) requires means to be provided whereby the supply ofelectrical energy can be switched off, 12(1)(b) requires that there will be available suitablemeans of ensuring that the supply will remain switched off and inadvertent reconnection

prevented. This is isolation. This provision, in conjunction with safe working practices, willenable work to be carried out on electrical equipment without risk of it becoming live duringthe course of that work, for example if the work is to be done under the terms of Regulation13.

4 In some cases the equipment used to comply with Regulation 12(1)(a) may also be used to

secure compliance under 12(1)(b). It must be understood that the two functions of switchingoff and isolation are not the same, even though in some circumstances they are performed bythe same action or by the same equipment. (University Code B.2, B.8, C.1, 2, 3, 4, 5, 6, 7, 8,9).

Regulation 13

States: 'Adequate precautions shall be taken to prevent electrical equipment, which has beenmade dead in order to prevent danger while work is carried out on or near that equipment,from becoming electrically charged during that work if danger may thereby arise.'

Comment: This is an extremely important regulation. (There are depressingly regularreports of fatalities due to 'dead' equipment being inadvertently made live bysomeone switching the power on elsewhere).


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Further explanation from the Memorandum is as follows:

'The precautions should be effective in preventing the electrical equipmentfrom becoming charged in any way which would give rise to danger.

In the first place the procedures for making the equipment dead will probablyinvolve use of the means required by Regulation 12(1)(a) for cutting off thesupply of electrical energy. Isolation of the electrical equipment will be

necessary and the means required by Regulation 12(1)(b) will facilitate this.Ideally a means of locking off an isolator can be used. Where such facilitiesare not available, the removal of fuses or links and their being held insafekeeping can provide a secure arrangement if proper control procedures areused.'

The guidance warns that these precautions may not be sufficient, for examplewhere stored electrical energy is present. It may be necessary to applyearthing connections at appropriate points. Before working on a 'dead' systemthe conductors should first be proved dead.

Formal written instructions, including permit-to-work arrangements should beused for high voltages or very complex systems. (University Code B.2, B.6,B.8, C.1, C.8, C.9).

Regulation 14

Refers to working on or near live conductors. The HSE's Memorandum gives a wealth ofdetailed advice on the hazards posed by 'live working' and the precautions to be taken wherethis is unavoidable.

Regulation 15

States: 'For the purposes of enabling injury to be prevented, adequate working space,adequate means of access and adequate lighting shall be provided at all electrical equipmenton which or near which working is being done in circumstances which may give rise todanger'.

Comment: This applies to any work, which may give rise to danger, not only liveworking.

Guidance in the HSE's Memorandum includes the following:

'2 The purpose of the regulation is to ensure that sufficient space, access and

adequate illumination are provided while persons are working on, at or nearelectrical equipment in order that they may work safely. The requirement isnot restricted to those circumstances where live conductors are exposed butapplies where any work is being done in circumstances, which may give riseto danger. The regulation makes no requirement for such space, access orillumination to be provided at times other than when work is being done. (Butsee guidance under Regulation 12(1)(a), in respect of safe access to means ofcutting off the supply).

5 Natural light is preferable to artificial light but where artificial light isnecessary it is preferable that this be from a permanent and properly designedinstallation, for example in indoor switch rooms etc. However, there will

always be exceptions and special circumstances where these principles cannot be achieved, where hand-lamps or torches will be the sole or most importantmeans of lighting. Whatever level of lighting is used it must be adequate toenable injury to be prevented.'


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The guidance on working space is reproduced as Appendix 3 to the UniversityCode. (The whole of Part C of the Code may also be relevant depending onthe circumstances).

Regulation 16 (Competence of persons carrying out work with electricity)

The Regulation states: 'No person shall be engaged in any work where technical knowledge

or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may beappropriate having regard to the nature of the work.'

The HSE Memorandum makes it clear that the object of this Regulation is that persons arenot placed at risk due to a lack of skill on the part of themselves or others in dealing withelectrical equipment. University Departments engaged in such work should review theirstaffing arrangements in the light of the advice given, with the aim of ensuring an appropriatematching of competence and assigned work activities. Other important interpretations are:

'...prevent danger or, where appropriate, injury...'

3 This regulation uses both of the terms 'injury' and 'danger'. The regulation thereforeapplies to the whole range of work associated with electrical equipment where danger mayarise and whether or not danger (or the risk of injury) is actually present during the work. Itwill include situations where the elimination of the risk of injury, i.e. the prevention ofdanger, for the duration of the work is under the control of a person who must therefore

possess sufficient technical knowledge or experience, or be so supervised, etc. as to becapable of ensuring that danger is prevented.

For example where a person is to effect the isolation of some electrical equipment before this person undertakes some work on the equipment, they will require sufficient technical

knowledge or experience to prevent danger during the isolation. There will be no dangerfrom the equipment during the work provided that the isolation has been carried out properly.Danger will have been prevented but the person doing the work must have sufficienttechnical knowledge or experience so as to prevent danger during that work, for example byknowing not to work on adjacent 'live' circuits.

4 But the regulation also covers those circumstances where danger is present, i.e. wherethere is a risk of injury, as for example where work is being done on live or chargedequipment using special techniques and under the terms of Regulation 14. In thesecircumstances persons must possess sufficient technical knowledge or experience or be sosupervised etc. as to be capable of ensuring that injury is prevented.

Technical knowledge or experience

5 The scope of 'technical knowledge or experience' may include:

(a) adequate knowledge of electricity;(b) adequate experience of electrical work;(c) adequate understanding of the system to be worked on and practical experience of

that class of system;(d) understanding of the hazards which may arise during the work and the precautions

which need to be taken;

(e) ability to recognise at all times whether it is safe for work to continue.


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Allocation of responsibilities

6 Employees should be trained and instructed to ensure that they understand the safety procedures which are relevant to their work and should work in accordance with anyinstructions or rules directed at ensuring safety which have been laid down by theiremployer.

Supervision

7 The regulation recognises that in many circumstances persons will require to be supervisedto some degree where their technical knowledge or experience is not of itself sufficient toensure that they can otherwise undertake the work safely. The responsibilities of thoseundertaking the supervision should be clearly stated to them by those duty holders whoallocate the responsibilities for supervision and consideration should be given to stating theseresponsibilities in writing. Where the risks involved are low, verbal instructions are likely to

be adequate but as the risk or complexity increases, there comes a point where the need forwritten procedures becomes important in order that instructions may be understood andsupervised more rigorously. In this context, supervision does not necessarily requirecontinual attendance at the work site, but the degree of supervision and the manner in which

it is exercised is for the duty holders to arrange to ensure that danger, or as the case may be,injury is prevented.

Further advice on working procedures is given in guidance publications listed in Appendix 1.(University Code: Introduction 1.2).

Regulations 17 to 28 apply to Mines and are not dealt with either in the HSE'sMemorandum or in the University's Code of Practice.

Regulation 29 Defence (in criminal proceedings).

Reference is made throughout the HSE's Memorandum to the 'defence', which is available inany proceedings for an offence under these Regulations. Some misinterpretations suggestthat if compliance with a Regulation is costly or inconvenient it can be ignored. Others, evenmore misguided and dangerous, suggest that the Regulations apply only to industrial andsimilar activities and that Universities are partly or even wholly exempt.

Such assumptions are wholly incorrect and liable to bring individuals holding such views,and their institutions, into conflict with the law, as the relevant text below makes clear:

'In any proceedings for an offence consisting of a contravention of Regulations 4(4), 5, 8, 9,10, 11, 12, 13, 14, 15, 16 or 25, it shall be a defence for any person to prove that he took all

reasonable steps and exercised all due diligence to avoid the commission of that offence.

Regulation 29 applies only in criminal proceedings. It provides a defence for a duty holderwho can establish that he took all reasonable steps and exercised all due diligence to avoidcommitting an offence under Regulations 4(4), 5, 8, 9, 10, 11, 12, 13, 14, 15 or 16.(Regulation 25 applies only to mines)'.

Regulations 30-33

These are procedural and administrative only and are omitted.

code of practice for electrical safety

Documents