House trips started going..... why?

Noname (yet). All I know atm is that the nuisance tripping *appeared* to reduce when that VDR was removed. The VDR is marked "GE U9 275L40B", which probably means a 275V(rms?) stand-off voltage. So that should be an ok design as long as the VDR is not faulty, and on normal mains voltages.

Reply to
Tony Williams
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Yes, other comments about replacing the Chilton have been noted. We will be getting a leccy in to do that (and a few other things). Thanks for a suggested specific type.

Reply to
Tony Williams

Trust me, it doesn't. Its not nearly as simple as you just suggested. Mixing a v-ELCB and an unbonded electric shower is not too clever.

You have a fundamental installation problem and need it sorting out. You might also have a faulty appliance, but that's secondary. Someone needs to carefully look over your earthing system.

With a v-ELCB in circuit and tripping you will almost certainly have no real earth in the place, and you may also have voltage differentials sufficient to cause electrocution in more vulnerable situations where human and water mix.

Understand this: the v-ELCB disconnects the whole house earth system in order to function. Its how it works. Your house earth loop must still be unearthed if the Chilton is tripping.

The basic use of the obsolete v-ELCBs is only secondarily for additional protection against small earth leaks, its primarily to make installations safe when there is an inadequate earth. When I say safe, I mean for obsolete values of safe, and in no way safe for use with an electric shower.

A v-ELCB on a wiring system is cause for caution. There are real issues with them. They allow some types of dangerous situations to occur without tripping.

normal.

I've got to ask, are you still taking electric showers?

Regards, NT

Reply to
N. Thornton

ony Williams writes

Yes.

No, definitely not. Should only be between L & N.

Normal mains voltage includes very short spikes up to several kV, and longer ones of several 100 Volts. During these spikes the VDR is only 100 Ohms or less, so it can put a lot of unbalance current thro the RCD for the duration of the spike if your earth is fairly good. These spikes can trip RCD's anyway on occasion, due to the house-wiring capacitance to earth and filters on electronic gear, without the help of spurious VDRs. If your electrician gives your installation a clean bill of health, but trips still occur, he can ask the supplier to but a transient recorder on site for a couple of weeks to see if your trips coincide with incoming rubbish. Normally foc.

You really didn't want to know all that did you, but maybe it will be useful to someone else following the thread.

Reply to
roger

Thought you were working your way up to a fine Mark Lamar rant there, Nick...

Reply to
stefek.zaba

:) I bet this guy is still taking electric showers too.

Regards, NT

Reply to
N. Thornton

Final followup;

I found an actual definitive perp. All appliances checked out ok, so isolated the incoming mains and started prodding around inside the CU. Found a Neutral-Earth short, disconnected all N's and found it was on an upstairs ring main, so started hunting for it.... Cutting a very long story, I finally found a low-R between E+N and the head of a nail, above particular 13A socket. Removed the nail, and all probs went away.

We've been having a lot of internal/external work done recently and this nail went in at about the same time as the incoming cabling was changed. I'm not blaming anyone though, because it is only about 2ft above the 13A socket, and a good 8" to the right of it. I now have to remember to warn people of the possibility of diagonal cabling under the plaster.

Note that (with our very low E-N voltage) the E-N short itself did not cause a trip, it required a certain amount of load current on that ring before there was enough unbalance current between the L-N wires.

Leccy's been in and done it, as suggested, thank you.

Reply to
Tony Williams

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