Electricity safety

1. Core 01 – Health, Safety and
Welfare in Construction and
Associated Industries
Work Safely Around Electricity

2. Tutor Copy

3. Electricity Hazards
Most hazards can be seen or felt or heard or smelt.
With electricity there is no advance
warning of the danger and electricity
can kill.
Electrical hazards arise through:
• Faulty installations.
• Lack of maintenance.
• Abuse of electrical equipment.

4. 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.

5. Check whether it’s dead before it
kills you

6. Power cables
Power cables are colour coded to identify:
• Live
• Neutral
• Earth
Voltage size will also be colour coded
• 110 volt – Yellow
• 240 volt - Blue
• 415 Volts - Red

7. Plugs
• Three pin plugs would get easily damaged
on site so special enclosed plastic sockets
are used.

8. Wiring cables for plugs
Neutral Live
Earth

9. 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 one of the following:

10. 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.

11. 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.

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

13. Extension Cables – Provide extra
outlets and extend existing outlets.

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

15. Residual Current Device
A 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 site
An RCD should only be
used with 240v equipment
as a last resort.

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

17. 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.

18. 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.

19. Electrical Hazards
Should be:
Reported to your
supervisor and
isolated

20. Storage of Electrical Equipment
Always follow manufacturers instructions with
regards to storing electrical equipment.
• Don’t handle or hang power tools by the
cable.
• Don’t store electrical equipment in damp
areas.
• Ensure transformers do not get cracked or
damage through poor manual handling.