New instalation

walton · Posted: Sun Sep 11, 2005 4:20 pm Post Subject: New instalation

We recently installed a new washing machine and dishwasher. Almost immediatly we felt electric shocks from both appliancies and wall socket securing screws. I immedialty switched the power off and checked the houses earthing. I tested the earth and was registering 110v on the earth while both appliancies were plugged in. once unplugged there was no reading. now i have installed a new CU with a 100A rcd with a 32 mcb for the kitchen sockets. there is still a reading of voltage in the earth but the RCD deos not trip, can you help

Spark123 · Posted: Sun Sep 11, 2005 4:29 pm Post Subject:

You get a reading of 110v between earth and where? Which earth did you test, the Main Earth Terminal (near CU)?

yai46 · Posted: Sun Sep 11, 2005 4:37 pm Post Subject:

in my experience your probably find that that socket has not got an earth wire connected at the socket in which its connected to, if it has a switched fuse spur above worktop check the earth has not come adrift from the terminal
What it sounds like is voltage is being induced into the earth and pipes due to being no earth .

walton · Posted: Sun Sep 11, 2005 4:38 pm Post Subject: new installtion

I got a reading both from the earth from the back of the socet after disconnecting and doing a reading to the earth feed, and from disconnecting the main earth feed in the CU

Spark123 · Posted: Sun Sep 11, 2005 4:43 pm Post Subject:

So the measurement was between the machine and the house earth. Please be aware that what you did to obtain this reading is very dangerous. You must never disconnect an earth from a live circuit. The voltage you were seeing was more than likely due to a mains filter in the washing machine.

walton · Posted: Sun Sep 11, 2005 4:47 pm Post Subject:

Yes agreed but why is there a reading in the first place, and even with the new CU installed I still get a reading through the earth which again I tracked down to the new appliancies. could they both be faulty, and if so why isnt the RCD (which is an 80 A not 100) not tripping.

yai46 · Posted: Sun Sep 11, 2005 4:49 pm Post Subject:

what have you used for testing the earth with.

walton · Posted: Sun Sep 11, 2005 4:49 pm Post Subject:

digital multimeter

Spark123 · Posted: Sun Sep 11, 2005 4:50 pm Post Subject:

walton wrote:

Yes agreed but why is there a reading in the first place, and even with the new CU installed I still get a reading through the earth which again I tracked down to the new appliancies. could they both be faulty, and if so why isnt the RCD (which is an 80 A not 100) not tripping.

It is the mA leakage which causes the RCD to trip. If the mA leakage is not high enough, the RCD doesn't trip.
What type of supply do you have? http://www.diynot.com/forums/viewtopic.php?t=7553&postdays=0&postorder=asc&start=9

walton · Posted: Sun Sep 11, 2005 4:53 pm Post Subject:

the mA reding was 6 and the voltage was 110v are the appliancies faulty

yai46 · Posted: Sun Sep 11, 2005 4:53 pm Post Subject:

try pluging the machine into an other socket in an other room via an extension lead, i would imagine your find that there is no problem with the appliance by doing this and the fault is due to the earth being no good or loose.

What is the continuity of the earth reading?

Spark123 · Posted: Sun Sep 11, 2005 4:56 pm Post Subject:

walton wrote:

the mA reding was 6 and the voltage was 110v are the appliancies faulty

No, not necesseraly.
6mA is not enough to trip an RCD (I assume it is 30mA?).
How many earth wires enter the socket (excluding the back box loop)?
Is the circuit a ring main?