Undertake basic electrical tasks

Electrical continuity bonding

This video shows you how to fit the earth to a clamp on copper pipe, caution must be taken when using knives. Try to use the correct tools always such as wire/flex stripping tools

Why

Main earth

Many electrical appliances - including cookers, washing machines and refrigerators - have metal cases. The earth wire creates a safe route for the current to flow through if the live wire touches the casing.

The current will always take the easiest path to ground; the idea of Main Bonding (and Supplementary Bonding) is to create an alternative path for the current to flow that is an easier path than along one of your heating pipes, along your arm, through your body, down your legs to the wet kitchen floor and to ground. By using a thick copper cable, you are creating a path that is more inviting to any fault currents and will divert any fault currents from your body or places where it should not go, as the current flows down to ground.

Remember

If you are fitting supplementary bonding and there are plastic fittings on the pipes cross bonding must be done so as to maintain the earth continuity.

Temporary continuity bonding

When working on pipework and cutting into pipework, the earth continuity is broken. By using these clamps before the activity takes place (put them on first before cutting) the risk of electric shock is eliminated

Testing

Earth continuity test

Find a known earth source (screw on cover or earth terminal).
Low reading OHM meter (or buzzer).
Place one probe on the known earth.
Place the second probe on appliance casing or pipework.
It should show a low reading (or buzz).

Short circuit

A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or a very low electrical impedance. The electrical opposite of a short circuit is an "open circuit", which is an infinite resistance between two nodes.

If the live accidently touches the earth, an earth fault will occur. If the live accidently touches the earth, a short circuit will occur.

Polarity test

This is carried out dead before allowing any electricity

Since a.c. installations consist of a Live and a Neutral conductor, it is extremely important that these conductors are connected the right way around, within all electrical accessories such as wall sockets or plugs. To ensure this, polarity test is done at each relevant point

If the dead test proves successful, you can make the system live and re-test. This time the multimeter needs to be set on voltage (230v).

Probes: Live and neutral = 230v

Live and earth = 230v

Neutral and earth = 0v

If these readings are different, polarity is incorrect.

Socket tester

A simple way to test polarity in a domestic socket is by using a socket tester. Plug it in and switch the socket on: if all three lights come on, the socket is fine.