240v electrical tests & inspections, how to preform the tests.

If you have had chance to look over our habitation check list you may have come across the 240v electrical tests. In this article we will look at each of these tests and how to preform them.

Earth Bonding

Bonding is used to reduce the risk of electric shocks to anyone who may touch two separate metal parts when there is a fault somewhere in the supply of electrical installation. By connecting bonding conductors between particular parts, it reduces the voltage there might have been.

This can be tested in the following order.

Perform safe isolation procedure. Apply lock out device.

Disconnect one end of the protective bonding. If possible disconnect at the consumer’s unit and test from the disconnected end and the metalwork which the bonding is connected to. This will test the integrity of the bonding clamp.

Connect the leads of the multimeter together and make sure that the reading is zero.

Connect one lead to the disconnected conductor.

Connect the other lead to the metalwork close to the bonding clamp

Remember to subtract the resistance of the leads from the total measured resistance, if the multimeter has not been zeroed before the test. If the meter and leads have been zeroed then the value measured will be the resistance of the bonding conductor.

Ensure that the bonding conductor is reconnected upon completion of the test.

The measured resistance must a value of not more than 0.05 ohms, as any parallel paths will result in the resistance measurement being lower. In case that the measured resistance is greater than 0.05 ohms, it must be considered as non- compliant and make a recommendation for improvement.

RCD and MCB

An RCD(residual current device) detects that electricity is being channeled through an unintended path, such

as a human being who has touched an exposed wire, the RCD intervenes to switch the circuit off immediately, thus reducing the likelihood of serious injury or even death. This can be easily tested by locating the rcd in the consumer unit and pressing the test button. This should switch the rcd into the off position disconnecting the power to the MCB`s(miniature circuit breaker).

This test should be performed at least every 3 months.

A more thorough test can also be performed at the sockets with an rcd tester.

Hook up plug and lead(condition & resistance)

We need to make sure our hook up lead is free from any defects. A good visual check of the lead for any cut knicks or splits. Also make sure both plugs are secure on the cord grips. The next thing to do is check the resistance on the cable with a multimeter. Finally plug in the lead to the mains and test the socket polarity. This can be done with a plug in socket tester. These will test for missing earth, missing neutral, live earth reverse and live neutral reverse.