Worrying 'Live Earth' problem.

Bleeding Amateur · Post by **Bleeding Amateur** » Mon Sep 04, 2006 12:04 pm

Hi guys

I have what I suspect is a fairly series problem with my home electrics. As background to the general condition of wiring, the house is a 1930s bungalow that had a significant extension in the late 80s and (as best I can tell) a rewire at that point- certainly the consumer unit is a modern type with RCD breakers and the cabling all seems to be modern PVC sheathed stuff.

Anyhow, the problem is this. If the electric oven is used, touching the kitchen or bathroom taps or the metal draining board will result in a very mild electric shock!!

Not a proper 'belt', more like a tingly static electric shock but still pretty concerning under the circumstances.

I'm assuming the oven is for the skip, that's not my biggest worry. I'm guessing there is a problem either with the water system bonding to earth, or the breaker circuits, or both. What I don't want to do is replace the oven, remove the side effect but leave a potentially dangerous problem lurking for the next time I get an equipment fault.

I checked the earth straps on the drainer, on the hot & cold water pipes in the kitchen and on the hot and cold water pipes in the bathroom, all were present but in varying states of loosesness so I cleaned and tightened those. That appears to have made no difference- when the oven is operated no fuses are tripped.

I won't be operating the oven again until it is replaced, but what to do about the apparent leakage of current to the earthing circuit?? I'm guessing the main body of advice will be 'get a qualified sparks round sharpish' and if that's the case, no worries and will do, but what is the most likely cause of the problem of fault with my system?

Many thanks in advance.

Steve G

tim'll fix it · Post by **tim'll fix it** » Mon Sep 04, 2006 12:24 pm

if you disconnect the oven do you still get a shock

I would call a spark

Bleeding Amateur · Post by **Bleeding Amateur** » Mon Sep 04, 2006 12:27 pm

Hi Tim

Thanks for prompt response (and apologies for all the typos in first post!!).

Nope, even if the oven is just switched off (as opposed to entirely disconnected), then there are no shocks at all.

Cheers, SG.

tim'll fix it · Post by **tim'll fix it** » Mon Sep 04, 2006 12:29 pm

sounds like the oven is the problem, in that case disconnect in now to prevent any damage and go out and buy a new one

Stoday · Post by **Stoday** » Mon Sep 04, 2006 1:10 pm

Sounds like the oven's earth is open circuit.

You'll always get a little leakage in any appliance with metal sheathed heating elements, but it's very small. If the earth is open circuit, the leakage can go through something else and you can get the little tingle you mention.

Bleeding Amateur · Post by **Bleeding Amateur** » Mon Sep 04, 2006 1:28 pm

OK, slightly reassuring and new oven on the way!!

I'd assumed that the oven was definitely the problem so good to have that confimed, but is it also a cause for concern that there's a tingly shock at the pipework? Should my RCDs not have tripped over and prevented the earth becoming 'live' (if indeed that is what's happening)?

I guess what I'm asking is- once the oven's replaced, should I have the house wiring checked?

Again, thanks for all your help! SG.

markysparky · Post by **markysparky** » Mon Sep 04, 2006 9:28 pm

Yes the earthing and bonding arrangements need checked and sorting.

Do you live in a rural area? If so the whole installation could have poor earthing arrangements, and would normally have an RCD for the whole house by todays standards, If your house is supplied by means of a TT system. (overhead lines)

Reccomend to get a leccy in and get a periodic electrical inspection report done.
You definitly have a problem somewhere

Bleeding Amateur · Post by **Bleeding Amateur** » Tue Sep 05, 2006 7:30 am

Yep, it is a rural area and it is fed by overhead lines so a general earthing fault is looking likely I guess!

So I need to be replacing the oven and having the general earthing/bonding checked too. Markysparky, could you explain to me in idiots terms about the RCD for the whole house thing you mention, and is the fitting of one an or disruptive expensive exercise?

Once again, thanks again for all your input!

markysparky · Post by **markysparky** » Mon Sep 11, 2006 10:49 pm

Sorry forgot all about this post

Because you live in a rural area the earthing of the house is the responsibility of the consumer and not the leccy board (who are responsible for the earthing on other systems)

A 100ma time delay RCD generally covers all the electrics on the house and could be used as a main switch.

All the sockets and shower should be on a 30ma RCD for added safety.

You could just put the whole installation on a 30ma RCD. But you could be prone to nusiance tripping frequently.

As for the earthing of the house. It needs an earth rod installed somewhere outside and it should not have an impedance any higher than 100 ohms

I strongly reccomend you get a leccy in to sort it.