Earth leakage problem

[Philani]

Much appreciated, thank you.

[Dave A]

Now, there something else I have discovered on that faulty earth leakage installation. When I perform the loop impedance and pscc test on the DB before the earth leakage, the readings i obtain are 265 ohms and 0.9 A (not kA) respectively. This is not making any sense to me. Any I deas?

Test at the meter. If it's fine at the meter, the problem is with the supply cable between the meter and the main switch.

[Henthel]

Are the socket outlets wired with a separate earth wire or are you depending on the conduit for an earth? I have found rusted conduit that will show an earth on the tester indicator light, but is inadequate to trip the earth leakage. Less than 30 mA flowing to earth. The tester lights may flicker and on some earth leakage units you will hear it hum, but it will not trip. A separate earth continuity test will prove whether you have a reliable earth. Most of the cheaper earth leakage testers will trip the e/l unit with next to no earth present but if there is really very little earth, it will fail to trip. In older houses you will also find that socket outlets are changed with newer ones with plastic casings. If the conduit was used as earth, the new plug must be equipped with a flying lead from the earth terminal that is securely earthed to the wall box. Is this problem on all the socket outlets or on one only? I have found homes where the distribution board was changed for a newer surface mounted unit and the earth bar with all the earth connections left in the old board in the wall, behind the new board and not connected to the earth bar in the new board. The new board is then in effect not earthed at all except for the wall plugs securing it to the brick wall. Lots of funny things pop up with tests.

[ians]

Are the socket outlets wired with a separate earth wire or are you depending on the conduit for an earth? I have found rusted conduit that will show an earth on the tester indicator light, but is inadequate to trip the earth leakage. Less than 30 mA flowing to earth. The tester lights may flicker and on some earth leakage units you will hear it hum, but it will not trip. A separate earth continuity test will prove whether you have a reliable earth. Most of the cheaper earth leakage testers will trip the e/l unit with next to no earth present but if there is really very little earth, it will fail to trip. In older houses you will also find that socket outlets are changed with newer ones with plastic casings. If the conduit was used as earth, the new plug must be equipped with a flying lead from the earth terminal that is securely earthed to the wall box. Is this problem on all the socket outlets or on one only? I have found homes where the distribution board was changed for a newer surface mounted unit and the earth bar with all the earth connections left in the old board in the wall, behind the new board and not connected to the earth bar in the new board. The new board is then in effect not earthed at all except for the wall plugs securing it to the brick wall. Lots of funny things pop up with tests.

It use to be common practice to fit surface DB's over old flush units.

Some bright sparks fit surface mount 4X4 pvc boxes over old 5 amp sockets or 4x2 flush mount sockets and just connect the 2 wires to the new plastic box and plug... when i contacted electrical contractor who fitted these boxes ever room in the entire duplex ... he said there is no way the labour he left on site would do such a silly thing.

This is why i believe it is important to carry out a random loop impedance test at socket outlets.