dsr 01 007 identification of high voltage...

UK Power Networks DSR 01 007v6.0

Identification of High Voltage CablesOwner

Name Peter VujanicTitle Head of Health, Safety, and Environment

Signature

Date 01 May 2016

Authoriser

Name Dudley SparksTitle Operational Safety Manager

Signature

Date 01 May 2016

This document forms part of the UK Power Networks Integrated Management System and compliance with its requirements is mandatory. Departure from these requirements may only be taken with the written approval of the above authoriser.

Revision RecordVersion number 6.0 What has changed?

Document Owner name changed. DSR 01 015 Identification of Points of Work added.

Why has it Changed?Change of structure.New procedure

Date published 01/05/2016

Next review date 01/05/2019

Prepared by R Hembling

Version number 5.0 What has changed?Section 8.7 additional use of cable identifier in some circumstances when tracing from a cable end box.And additional example added to reasons not to spike.Section 8.10 wording added to allow a second SAP to confirm that spiking is the only option remainingSection 8.11 wording change for clarity.Section 8.13 I The word suspended removed

Why has it changed?Variations to working practicesFeedback from Field operatives.Actions from Incidents



Prepared by R Hembling

Version number 4.1 What has changed?Two sentences added to section 8.4 regarding the use of mobile phones whilst identifying a cable using signal injection.

Why has it changed?Field use Feedback



Prepared by N Saunders

This printed document is valid at 05/05/23, check after this date for validity. of 17


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Contents

1.0 Introduction and Purpose...............................................................................................32.0 Scope................................................................................................................................33.0 Objective...........................................................................................................................34.0 References.......................................................................................................................35.0 Definitions........................................................................................................................36.0 Responsibilities...............................................................................................................47.0 Records............................................................................................................................48.0 Process Detail..................................................................................................................49.0 Superseded Documents................................................................................................1110.0 Appendix A Identification of Cables by Signal Injection.......................................1211.0 Appendix B Spiking Information..............................................................................16



1.0 Introduction and PurposeThis document gives the Approved procedure for identifying HV cables, the Approved spiking procedure and other Approved means, which are required to comply with DSR 5.9.2.

This document gives the approved procedure for moving a previously identified point of work, to another position on the same cable (or circuit).

2.0 ScopeAll operations in UK Power Networks Licence areas and on private networks that are owned or managed by UK Power Networks.

If any field operative requires to use any other means, then the field operative must obtain the consent of the Designated Engineer.

3.0 ObjectiveTo prevent injury to any person who is to work on a High Voltage (HV) cable.

To prevent damage being caused to the network Plant and Apparatus.

To prevent the inadvertent interruption of electricity supply to customers

4.0 ReferencesDSR Distribution Safety Rules (Principally Rule 5.9.2)DSR 01 018 Identification of LV cablesDSR 01 014 Excavating near electricity cablesDSR 01 015 Identification of Points of WorkHSS 40 029 Unidentified cables

Approved Instrument ListHSS 01 139 Maintenance of spiking guns and cartridge storage

GTRA JHV 02 HV Jointing (including cable identification, stripping and preparation)

GTRA GOP 22 Identification of point of work and issuing of safety documents

GTRA EHV 10 EHV Jointing (including cable identification, stripping and preparation)

5.0 Definitions

Spiking The use of a cartridge operated spiking gun, or other approved device, which causes severe damage to the cable.

A conventional cartridge operated spiking gun causes a metal chisel to penetrate the cable, to cause the damage. The method in which the spiking gun is used will depend on the type of cable being spiked.

Hydraulic cutters are not to be used instead of a spiking gun.

Possible consequences of spiking an incorrectly identified cable are



given in appendix B.

6.0 ResponsibilitiesIt is the responsibility of all UK Power Networks employees and contractors working for UK Power Networks, to comply with the requirements of this procedure.

In particular, it is the responsibility of the Senior Authorised Person (SAP) in charge of the work, to correctly identify the HV cable and prove it Dead.

7.0 RecordsThere are no specific records.

8.0 Process Detail

8.1 General RequirementsBefore any work is undertaken on a High Voltage (HV) underground cable that is a part of the distribution network, then it shall first be made Dead, Isolated and Earthed in accordance with the Distribution Safety Rules, identified at the point of work by an approved method and proved Dead by approved means.Where the work is to be carried out externally to the metallic Earth sheath (e.g. cathodic protection bonds, insulating sheath repairs etc.), confirmatory spiking is not required. However, it is essential that a Permit-to-Work (PTW) is issued by the Senior Authorised Person. The points of Isolation and Earthing shall be recorded on the document and Danger Notices posted on adjacent Live equipment.

8.2 Cable RecordsCable records give an indication of cable routes, type of construction and voltage. They give no reliable indication of depth, as ground levels may have altered over the years, or a cable’s position may have been changed by a third party without consent and not recorded. They should be seen as providing a guide, rather than a detailed location plan for a specific cable. Records should be used as a first step to locating and identifying a cable.

Cables may be encountered that cannot be identified by reference to cable records. These may be private or abandoned cables that have not been recorded. In these circumstances, the unidentified cable procedure HSS 40 029 should be followed.

8.3 Excavation of Joint HolesWhere there are other cables near to the cable to be identified, then any nearby relevant cables (cables that cannot be reliably eliminated) must also be exposed. Signal injection (see 8.4) may be used to identify the cable, in which case a comparison of the signal strength on each cable and whether the signal strength varies as the detector is moved around, or along the cables, will help to determine which cable has been injected with the signal. Particular care is required when using a detector around rather than along a cable. This is because any variations in signal strength may be due to changes in distance from a nearby cable rather than due to the internal twisting of the cores of the cable.

If in doubt, seek advice from a SAP.



8.4 Identification by Signal InjectionSignal Injection is the preferred method of cable identification. The cable shall be isolated and earthed in accordance with DSR 4.1.1. A Sanction-for-Test (SFT) must then be issued.

The signal injection instrument (see approved instrument list) has two leads which must be connected between two cores of the cable. This connection is made by the use of test plugs, or integral test connections on switchgear (if available), or to an accessible cable termination such as an overhead line, or cable sealing ends.

The person connecting the instrument must ensure that the connection points have been effectively earthed to discharge all stored electrical charge, before they are approached or touched.

The person conducting the test must consider if a second person is required during the testing. This second person must be competent to avoid danger and must also understand what is being done.

It is essential that the instrument leads are connected between two phase cores, so that the signal does not find alternative earth paths and so reduce the possibility of an unwanted signal on another cable.

The remote end of the cable will usually be in the earthed position. The earth will provide a short circuit path between all phases.

On teed or multi-branch circuits, it may be necessary to remove and apply earths appropriately, so as to be able to identify the correct Branch of the cable (see appendix A).

At the point of work, the signal shall be picked up by the use of a detector. If the detector is moved around, or along, a conventional cable, the signal strength will vary due to the internal twisting of the cores. This variation in signal strength will demonstrate that the signal is in the cores and not in the earth sheath of the cable.

When possible, it is preferable to move the detector along the length of the cable, rather than just around the circumference of the cable. Experience has shown that this normally gives a better result, as the detector traverses a greater distance.

If the signal strength is constant, as the detector is moved around or along the cable, then the cable may not be the correct one. Further tests and investigation will then be required.

If the cable is accessible at a location other than the joint hole, and its identity is known then an instrument that induces a signal into the sheath of the cable may be used. The signal is induced usually into the sheath of the cable by using a Current Transformer and a signal detector is used to detect the signal at the point of work (see also 8.12).

The detector shall be used to listen for the presence or absence, of a signal on all the exposed cables.

Be aware that a signal may be induced from mobile telephones into the listening device. Switch OFF all mobile telephones when using this type of equipment.

Operatives using the signal equipment shall ensure that they are familiar with the equipment and know how to use it correctly.

Following the identification of the cable by signal injection, the cable shall normally be spiked (see 8.6).



8.5 Identification of Single Core Cable CircuitsThe introduction of polymeric insulation has led to the wide spread use of single core cables. These are mostly used in groups of three to form a circuit, instead of using a composite three core cable.

Additional care is required when identifying circuits comprising of three single core cables, when there are other nearby circuits which also comprise single core cables. There is some possibility that the cores may have incorrectly been placed in groups of three, thereby meaning that the group of three single core cables may not belong to the same circuit. Even if the single core cables are in a duct, or have been tied together, the possibility may still exist that they do not belong to the same circuit.

By attaching the signal injector leads to two phases, it is usually possible to determine which two of the three single core polymeric cables have the strongest signal. By disconnecting the signal injector lead from one of the phases and connecting it onto the phase that was not previously injected, it will usually be possible to then identify the third single core cable which previously did not have a signal. If the signal is weak or non-existent in any of the three single core cables, it is possible that the cables have been incorrectly grouped. Further tests and investigation will then need to be made.

8.6 Exceptions to Spiking a CableExceptions to spiking a cable are restricted to the following work (and those detailed in the following sections of this procedure):

Work on pressurised primary system cables that does not involve disturbing the main insulation of the cable, for example:

a) sheath repairs;

b) temporary leak repairs;

c) repairs to apple wipes and band wipes;

d) removal of a fibre glass joint box or heat shrink sleeve for joint inspection;

e) freezing;

f) application of epoxy resin sheath reinforcement;

g) serving repairs on insulated sheath cables

h) removal of a ring of sheath to inspect and repair minor surface impact damage on pressurised cables, where it is considered that a sleeve repair can be carried out ;

(II) The complete break down and remake of a primary system pressurised joint to carry out repair work.

(III) Exception to spiking primary system polymeric and paper solid cables is restricted to the following work only:

topping up oil filled reservoir joints on paper cables.

serving repairs.

Where the work to be carried out is of the type described in this section and in the opinion of the SAP it is safe not to spike, it will not be necessary to do so, provided the procedures detailed below are complied with.

At the point of work the SAP will explain to the person who will receive the PTW how the cable has been made dead and where it has been earthed. The SAP will then show that the cable can be identified by reference to records. This will include reviewing any available



circuit history accompanying the records, with particular attention being paid to any historic work on a circuit and the impact this work might have had on the cable layout or joint designations at the point of work.

The SAP will inject a signal into the cable and will listen at the point of work as required by section 8.4. In addition where there are adjacent live circuits the listener should also be used to confirm the absence of mains hum in the identified cable when compared with the live cables.

Where (ii) above gives a very positive result, but is at variance with the records and this cannot be explained then, where reasonably practicable, adjacent live cables should be made dead. If this is not reasonably practicable and it is still considered safe not to spike then a second SAP familiar with cable work will be required to visit site and satisfy themselves that all precautions have been taken. The second SAP will confirm that they agree that it is not necessary to spike the cable, and this will be written on the PTW. The second SAP will endorse the issue of the PTW by signing alongside the person issuing the PTW. This will be recorded with Control. Work on the cable will be started under the personal supervision of both SAPs.

In any case where (i) and (ii) above give ambiguous results or cannot be complied with, or it is considered unsafe to proceed without spiking, with the adjacent cables, then the adjacent cables must be made dead, or the cable must be spiked.

8.7 Identification by cable tracingIt may be reasonably possible to trace a cable from a known Earthed position, such as:

A switchgear cable end box: Care is required due to the different layout of cable boxes on switchgear especially that controlling Transformers and where reasonably practicable the identification shall be confirmed by using signal injection.

A cable sealing end

An overhead line

The cable must be positively traced along its entire route from the known earthed position to the point of work. A noose of non-conductive material shall be run from the known Earthed termination, to the point of work. If it is not possible to use a running noose, then another approved method must be used (e.g. signal injection).

When identifying a cable by cable tracing and the cable passes through a hole in a wall, it is mandatory to run the noose through the hole. Tapping or tugging the cable, using rods, or any other unapproved techniques are prohibited.

Where a cable passes through a duct line, it is prohibited to rod the duct as a method of identification. There have been instances where this technique has failed in the past, when the rod has passed from one duct line into another, so giving incorrect cable identification.

A cable that is identified at the point of work by positive tracing shall normally be spiked. However, where the cable has been identified by positive tracing and the SAP has good grounds not to spike the cable, then the cable need not be spiked.

Three typical examples of good grounds are:

A physical restriction or difficulty preventing the application of the spiking gun.

That the spiking of the cable would result in the need to extend the cable, so producing additional work.



Where the earth connection is clearly visible and the cable has been physically traced from that earth.

8.8 Transformer Feeder Identification, by Signal Injection Method (HV/LV)Where HV test access is not available, to simplify the procedure and avoid the necessity for removing the lid of the distribution transformer, the test signal may be injected into the LV winding, with an earth applied at the source end of the HV cable (see appendix A). Due to the turns ratio of the transformer windings, the signal current produced in the HV cable will be smaller than with direct injection but it is still normally adequate for identification purposes.

A phase to phase connection for signal injection into the LV winding is preferable, although a comparable signal level can be obtained by connecting between phase and neutral. (The primary and secondary windings of the transformer are linked solely by electromagnetic coupling and the presence of a single earth connection on each voltage system i.e. HV cable earth and LV neutral earth connection, will not cause signal current to flow in the cable sheath or via earth return paths).

It is imperative that the intended points of attachment of the signal injection leads are tested before connection is made, to ensure that they are not Live.

Fused leads shall be used when being connected onto stalks of a LV distribution board.

8.9 Identifying a Spur (Pot / Stop Ended) HV CableWhere work is required on a stop ended cable, such that signal injection cannot be utilised, and it is also not possible to trace from a known earthed point, then cable records shall be carefully consulted.

If the cable is accessible (and its identity known) at another location, then there are instruments that are available that can induce a signal into the cable (usually the sheath). A signal detector can then be used to see if the induced signal can be detected at the required point of work.

If there are other cables present near the point of spiking, then identify the other cables so that they can be eliminated.

Before spiking and under a SFT, connect a signal injection instrument to the cable cores. Also check at the intended point of spiking with a detector, to see whether there is any form of signal (there should be no detectable signal).

After the spiking, check for the presence of a signal in the cable, on the side of the spiking gun to which the signal is being injected into the cable. The presence of a detectable signal will indicate that the correct cable has been spiked.

8.10 Identifying Faulted HV CablesDue to damage, it may not be possible to use signal injection to identify a HV cable which has tripped on fault. The damage may have caused a high impedance fault, or an open circuit fault, preventing the injection of a signal into the cable. In such cases, subject to an on-site point of work assessment the use of the electrical discharge equipment that is used to locate HV faults should be considered to identify the cable.

In this situation, the excavation in which the faulty cable has been exposed will need to be guarded, whilst the discharge equipment is in use. In addition, the exposed point of fault or damage must not be in contact with other cables; this is to prevent the electrical discharge causing damage to adjacent healthy cables.



If a clear unambiguous discharge is observed, this can be used as a means of positive identification.

Once the cable has been identified by this method, the cable shall be spiked.

In the very rare case that a cable cannot be identified by signal injection or by using the electrical discharge equipment mentioned above but it is believed that the cable in question is the required cable (e.g. from consulting cable records), then an attempt to identify the cable by inducing a signal into the cable, as described in 8.4 above shall be considered.

If all other approved identifying techniques have proved unsuccessful then a second SAP familiar with cable work shall confirm there are no other alternatives. A cable identifier shall be connected and with the consent of the Control Engineer the cable shall be spiked and verified as per 8.13 below.

If there is a joint at this location, then the cable shall be spiked on both sides of the joint.

If the cable in question has been severed, then both sides of the severed cable shall be spiked at a suitable position.

8.11 Identification of a HV Cable Terminating on a HV/LV Transformer(HV Cable End Box)

If the HV cable to be identified terminates on the end box of a HV/LV transformer, then provided the HV circuit has been disconnected (switched out deliberately) with a three phase ganged device, it will be sufficient to prove the HV cable dead by testing for LV volts before isolation and the absence of voltage on the LV transformer links or connections after isolation

If a safety document is to be issued on the cable, then it shall be earthed in accordance with the DSRs.

Where the HV protection is by independent fuses in the circuit, without an associated three phase controlling switch, such as in a Fused Ring Switch, Fused End Box (FEB), pole mounted drop out fuses, or Ring Disconnector Unit (RDU), this test will fail if two fuses have ruptured, therefore unless a healthy circuit has been switched out deliberately, the cable shall always be spiked.

8.12 HV Cable identification by inductionIn exceptional circumstances the SAP may decide that it is not necessary to verify the cable circuit being worked upon. This is typically when an induced signal (for example using a Bauer instrument) has been used as a means of identifying the HV cable and will only be acceptable in remote locations, where there is little chance of a second cable and the risk of undertaking a verification outweighs the risk or working on the wrong cable (i.e. testing from a pole at height). Before adopting this method consideration must be given to the possibility of other cables, which may not be owned by UK Power Networks.

A CAT and Genny are not an acceptable method of cable identification.

8.13 Procedure for SpikingFollowing the identification of a cable, the cable will then need to be spiked to ensure that it is not Live at HV. The following procedure shall be followed:

a) If the process has not already necessitated a Sanction-for-Test, then a SFT must be obtained from Control (A SFT cannot be issued for idle or abandoned cables that are not part of a network, as Circuit Main Earths cannot be applied).



b) If the cable has been identified by signal injection, it is not necessary to disconnect the instrument and re-apply the Earth.

c) The consent of the Control Engineer must be obtained prior to spiking.

d) Spike the cable.

e) Call Control and ask if any alarms have been received.

f) Before the spiking gun is removed, at least one of the verification tests, given below, must be conducted.

g) Following a positive result of the verification test, the earths will be re-applied and remain applied whilst the spiking gun is removed under the SFT and under the Personal Supervision of the recipient of the SFT. (this does not preclude the option of the SAP to issue a PTW to remove the spike gun)

h) Furthermore, under the same SFT and following the removal of the spiking gun, the cable may be opened and stripped for phase colour tests to be made under the Personal Supervision of the recipient of the SFT (this does not preclude the option for the SAP to issue a PTW to open and strip the cable).

i) SFT to be cancelled and a Permit-to-Work shall be issued for work to commence on the cable.

Injected Signal Strength Verification

Listen to the signal on either side of the spiking gun.

The signal strength on the side on which the signal is being injected should be distinctly louder than that on the furthest side. This is because the spike driven into the cable will be providing a short-circuit route for the signal. Therefore much less signal, if any, will flow to the end of the cable where the circuit main earth has been applied.

Verification by Insulation (Megger) Testing

Prior to spiking, remove all the Earths and megger the cable. The cable can be tested between phases and between phase to Earth.

The tests should show healthy insulation values.

After spiking, test the cable again. The results should show a faulty cable, thus proving that the correct cable has been spiked.

Why Must Control be Contacted Before Spiking?

It is a requirement of DSR 5.9.2.

The consent of the Control Engineer must be obtained before spiking, to alert their attention that an incorrect spiking may have occurred, if an alarm is received.

The Control Engineer also has a final opportunity to prevent the spiking, if a feeder trips on the network in that vicinity. The circuit may be required to support the load and so the job may have to be postponed.

Why Must Control be Contacted After Spiking?

It is a requirement of DSR 5.9.2.

The Control Engineer must be contacted after spiking, so that a check may be made for any alarms that could be linked to the spiking. The Control Engineer may need to check with other Control Engineers. This is because there have been occasions when cables have been incorrectly spiked and the alarm has been received and accepted by



another Control Engineer and not communicated to the Control Engineer dealing with the cable spiking.

8.14 Spiking Requirements of Circuits Comprising of Single Core CablesIn normal circumstances the spiking gun should be applied such that all three cores are spiked. However in the following circumstances it is essential that all three cores are spiked:

11kV Networks with Arc Suppression Coils 11kV Networks fed from Unganged Fuses Pot / Stop Ended Circuits

General

There may be occasions [excluding (i), (ii) or (iii) above] where it is only required to work on one or two of the single core cables. It would therefore be undesirable to spike and damage all three.

If only one or two of the single core cables are to be spiked, then insulation tests before and after spiking shall be conducted, to confirm that the correct circuit has been spiked. It will be necessary to use an instrument that applies a sufficiently high voltage, to detect the damaged caused by the spiking. This is necessary, as the single core cables may be completely severed by the spike and may appear as an open circuit (and therefore healthy), if the voltage applied by the instrument is too low.

8.15 Re-location of point of workFollowing the positive identification and spiking of a cable, it may be necessary to change the point of work after issuing a Permit to Work e.g. when dampness testing. This may be done, without reference to the Permit issuer, and without the need for further spiking, provided that the Permit holder can physically trace the cable by means of a running noose from the initial point of work, to the new point of work.

9.0 Superseded DocumentsHSS 40 030

SEEBOARD Engineering Instruction EI 9/5/13

Eastern Electricity, Engineering Divisional Manual, System Operations, Identification of dead HV cables, V12/S1/3.

HSS-406-OB-50

LPN Code of Practice 2.



10.0 Appendix A Identification of Cables by Signal InjectionGeneral

The following examples illustrate the methods to be adopted when identifying cables. Although very simple circuits are shown, the principles apply to more complex circuits.

In the case of a trefoil group using polymeric single core cables, if there is more than one circuit present, the test shall be repeated with the sender connections changed to a different combination of cores, so as to prove that the three single core cables to be worked upon, are part of the same circuit.

Plain Feeder

The signal injection device is connected to one end via test plugs, or test connections.

The other end of the cable is connected to Earth.



Teed Feeder

It is necessary to perform at least two tests, preferably leaving the sender connected at the same point throughout.

Test 1 Ensure no signal detected. Do not spike until the second test has been completed.

Test 2 Detect signal then, after spiking, ensure signal disappears on earthed side of spike.



Direct cable connection to a Distribution Transformer

If it is not possible to make direct connection to the cable a signal may be injected through a distribution transformer.

Remember that the LV may still be Live in part of the feeder pillar or cabinet.

Connecting the sender unit to a Live supply will cause serious damage.

Recommended Practice When Using Signal Injection

When the signal injection instrument has been connected to the circuit and the signal is being injected, before leaving the point of injection (usually an item of switchgear), it is good practice to use the signal detector at that point, to ensure that a satisfactory level of signal is present in the cable. The opportunity can also be taken to listen to the character of the signal, so that a comparison can be made later, at the point where the cable is required to be identified.

At the intended point of work, where the cable is required to be identified, all cables must be checked with the signal detector, as explained previously in section 8.4.

If no signal is detected on the exposed cable, or if the signal is very weak, the signal detector can be used to check the ground below the cable, or the sides of the excavation, to see if a signal can be detected from an unexposed cable. Even if a satisfactory signal is detected on the expected cable, it is good practice to check the soil in this manner, as this may give an indication of any cable carrying the signal, which has not been exposed.

See diagram over the page



The diagram below gives guidance on the optimal position to use the signal detector, when there are multiple three core cables present.



11.0 Appendix B Spiking Information Spiking guns may be used under the personal supervision of an Authorised Person, at all fault levels and at all voltages up to and including 132kV. The manufacturer's operating instructions shall be strictly observed, particularly the warning with regard to the release of trapped gases before the removal of a spent cartridge. After use, the equipment shall be inspected, cleaned and if necessary, maintained by a suitably trained person In accordance with HSS 01 139.

The gun shall always be remotely fired by the use of the lanyard ensuring no one, including third parties, are in the vicinity of the gun at the time of firing.

Clamping accessories are available to cater for the spiking of single core cables.

The clamp consists essentially of a parallel-sided slot in which the 3 cables to be spiked, together with a short length of scrap cable of the same size and type, are placed in a 2 over 2 configuration. The additional short length of scrap cable is always placed in the bottom of the slot. The parallel sides of the slot prevent the cables from moving apart when the gun is fired and all four cable cores are penetrated.

The clamps are not restricted to use with single core polymeric cables and may be used with three core cables, if one of the slots is of appropriate width for the cable to be spiked. Some slight extra packing may however be needed under a three core cable, to bring its upper surface to the correct level, so that the spike is fully retracted before firing.

Cartridges are available in 4 grades of loading:-

Red Mark (20 grain Charge)

For armoured copper cables greater than 86mm

(3 3/8")0D.

Green Mark (16 grain Charge)

For armoured copper cables up to 86mm

(3 3/8")0D.

Silver Mark (12 grain Charge)

For 3 core Al/Polymeric cables and single core Al/polymeric cables of 150 & 240 sq.mm. CSA.

Yellow Mark (10 grain Charge) For single core Al/Polymeric cables of 70 sq.mm. CSA.



Cartridge FailureIf during the process of spiking the cable, the cartridge fails to fire, remain at a safe distance for at least three minutes, before approaching the spiking gun to replace the cartridge.

Consequences of an Incorrect Cable SpikingIn the event of incorrect cable identification, the following consequences may occur:

Incorrect Spiking of a Live HV Cable

The resultant damage will operate the source protection of the live cable and cause an alarm to be sent to Control. If there is “downstream” protection on the HV feeder, before the point of spiking, or if the cable belongs to another party, then it is probable that no immediate information will be received at Control.

An incorrectly spiked HV cable, belonging to another party (such as an Independent Distribution Network Operator) could be re-energised by that party, following its initial spiking and consequential circuit tripping. This would result in serious danger. It is therefore essential to obtain positive verification by an approved method, as detailed in section 8.11, when identifying a cable by signal injection.

Incorrect Spiking of a Dead, Isolated or Abandoned HV or LV Cable

There would be no indication of an incorrect spiking. It should be appreciated that if a spiked isolated cable was to be unknowingly energised, serious danger would result.

Incorrect Spiking of a Live LV Cable

The spiking may not produce any observable signs (such as sparks, flames or smoke) that the cable is live. It should be appreciated that after the spiking, the cable could still be live on one or more phases which could also make the spiking gun live.

In the event of the spiking of the wrong cable, the field operative shall not remove the spiking gun. The Control Engineer shall be informed of the error and the Control Engineer will give further instructions.
