Core 01 Health, Safety and Welfare in Construction and Associated IndustriesWork Safely Around Electricity

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Electricity Hazards

Most hazards can be seen or felt or heard or smelt.

With electricity there is no advancewarning of the danger and electricity can kill.

Electrical hazards arise through: Faulty installations. Lack of maintenance. Abuse of electrical equipment.

Causes of Electric Shock

Electric shocks are caused by contact between a live electric conductor and an earth.However, shock is not the only hazard. Electricity can produce amounts of heat, depending upon the size of the current, and if the current passes through a flammable material, it can ignite the material causing a fire or explosion.

Check whether its dead before it kills you

Power cablesPower cables are colour coded to identify:LiveNeutralEarth

Voltage size will also be colour coded 110 volt Yellow240 volt - Blue415 Volts - Red

PlugsThree pin plugs would get easily damaged on site so special enclosed plastic sockets are used.

Wiring cables for plugs

NeutralLiveEarth

Electric Supply

A public supply from a local electricity company.

A site generator.The supply of electricity to homes and on site will normally be provided by oneof the following:

Overhead power lines are thick cables capable of carrying electricity of in excess of 33,000 volts. Electric Supply

Supplies below this voltage may be either overhead or underground.

Supply of Electricity to Building Site

Electricity to a building site should always be distributed by means of a reduced voltage system.

Woodworking machines require a 415 volt supply. Lighting requires a voltage of 230 volts. Portable tools require a supply of 110 volts.

Transformer Outlet Units These provide electricity of 110 volts for portable tools and extension outlets.

Extension Cables Provide extra outlets and extend existing outlets.

Markings

All supply and distribution and transformer units should be marked with the warning sign shown below.

Residual Current DeviceA residual current device (RCD) will cut power as soon as a surge is felt.This surge could be from a broken cable or faulty tool.

110v should always be used on siteAn RCD should only be used with 240v equipment as a last resort.

Buried cables

All buried cables should be: At least 0.5m below ground. Protected with tiles, covers or placed in a duct.

Cables on the ground

The use of electrical cables placed on the ground is dependent on the nature of the work being carried out, and should be:

Only permitted for short periods.

Provided with additional protection, such as a reinforced sleeve.

Clearly marked, so as not to cause a tripping hazard.

Suspended cables

Suspended cables are permissible on condition that:

There is no tension or strain on the connections.They are marked for protection.They are supported on proper hooks and not nails.Wires on poles support spans of over 3m.They are at a minimum height of 5.2m above ground.

Electrical Hazards Should be:Reported to your supervisor and isolated

Storage of Electrical EquipmentAlways follow manufacturers instructions with regards to storing electrical equipment.

Dont handle or hang power tools by the cable.Dont store electrical equipment in damp areas.Ensure transformers do not get cracked or damage through poor manual handling.

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