Bathroom cabinet electrical shock?

A 'bleep' only says the resistance is within certain limits. Although better than nothing.

Reply to
Dave Plowman (News)
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Earth continuity conductor. The 'E' in TW&E.

How old is the house wiring? Has the CU got a built in RCD? Fuses or MCBs? Was this cupboard added to the original installation or the supply to it run in at the same time as the house was wired? Lots of variables, I'm afraid.

Reply to
Dave Plowman (News)

It must be an old term:-) We use CPC -circuit protective conductor now.

Reply to
ARWadsworth

Is it now TW&C? ;-)

Reply to
Dave Plowman (News)

Ok, investigating this as we speak (post/google/thread/whatever)!

CU (understairs) is MCB variety... no split loads with RCD (or RCBO's: I wish!!) The system has been extended around the house in many areas so, as you say... many variables!

Perhaps I do need to call in my pal and get the whole place tested, corrected and certified then.

Latest: just switched off all the appliances and unplugged them, in the utility cupboard and the tingling has stopped! Something awry there then... time to put them back on one at a time and identify the correlation!

Also... you must be old :) what's the 'T' and the 'W' of TW&E then? Can't find it anywhere on t' web ;)

Reply to
deano

Twin and earth cable.

What earthing have you got at the main incoming fuse? It could be missing or have a very high impedance.

Reply to
ARWadsworth

I thought that was T&E, not TW&E or is it just another way of putting it?

Sorry, not sure what you're asking here? Could you ask me in idiot terms :)

Reply to
deano

Tumble Dryer!

Unplugged from utility cupboard = no tingle! Plugged into different outlet on other side of cupboard = no tingle!

or wall outlet where first plugged in???

or close proximity of dryer to cabinet???

Aaaah, it's like a dangerous version of pin the tail on the donkey!

Reply to
deano

It's all here for when you are on your laptop

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Reply to
ARWadsworth

Washing machine plugged into original wall outlet (where tumble dryer was) = tingle

So... wall outlet faulty? Loose connections? Will take a look!

Reply to
deano

I wondered if that's what you were referring to. I don't think the problem = here is that far up the stream, as the mains Earthing in the house has been= in situ since I moved here, some 14 years ago and has been tested in anger= IIRC at various times with short circuits and fuses blowing but I get that= you're covering the bases and going to the worst case scenario, identifyin= g the source.

As I've since posted... I've narrowed it down to certain wall sockets in th= e utility cupboard... I think :)

Reply to
deano

But if you had a Live->Neutral short or other overload the fuse would blow without any assistance from an Earth connection.

So the washing machine and/or tumble drier plugged in elsewhere probably have suppression capacitors fitted between L/E and N/E, how close are those sockets to the cabinet in question, how far to the consumer unit (fuse box)?

Do you pickup a tingle from these other appliances themselves?

Reply to
Andy Burns

I suppose first thing is to check the earth back to the earth bar at the CU.

Reply to
ARWadsworth

I am never going to be old, just more experienced!

TBH I am one of the worst culprits on this newgroup for just using terms such as earth and ring circuit when answering questions insread of the correct terms.

Reply to
ARWadsworth

ok, attempting to keep up with this - but no quoted context and no threadding is making it difficult. Deano, have a read of:

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see if you can find a way that works properly. Right now every message you post starts a whole new thread.

That fact that the house has earthing does not actually mean its any good. It might be advised to find someone with an earth loop tester that can measure your actual earth loop impedance.

Where is the utility cupboard in respect to the bathroom cabinet?

Reply to
John Rumm

I think he meant CPC, circuit Protective Conductor - aka earth wire

Reply to
John Rumm

You normally just reply at some point in the thread hierarchy - most folks probably have their newsreader software set to show stuff in a threaded hierarchy like:

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makes it fairly obvious.

ok, these are normally double isolated with only two connections on the input for L&N.

The cabinet sounds like it has an earth to guard against becoming live as a result of a wiring fault in the cabinet, rather than any problem with the transformer.

FSU I take it is a Switched FCU (Fused Connection Unit)...

A) yup - do that. b) not really much point since there is no requirement for supplementary bonding in a kitchen. There is a requirement for bonding in a bathroom - but that needs to be implemented in (or very close to) the room itself. (you also don't need an explicit connection back to the main earth terminal for supplementary bonding).

More on that here:

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the cabinet flex has an earth wire (or CPC (Circuit Protective Conductor) if you want to get posh), then this can be used for purposes of both earthing and equipotential bonding. So if its connected to the earth of the circuit that is supplying it, and that earth is also connected to the earth of any other circuits feeding the bathroom, plus any other metal systems that would be capable of introducing a "potential" into the bathroom, then everything that needs doing there has been done.

My guesses from what you have posted here and in other posts:

1) The cabinet is probably working fine. Its transformer is double insulated and can probably be forgotten for the purposed of this investigation.

2) The tingle is getting to the cabinet *from* its connection to the house earth. The fact that you can sense it only when making connection to both the tap and the cabinet suggests that the equipotential bonding in the bathroom is suspect.

3) Your Tumble Drier and Washing Machine will both have mains filters on the inputs. These will tend to try and float their input earth wire connection at half mains potential[1] unless they are properly earthed. [1] Although the earth is only connected by very small capacitors in the filters - hence the tingle ought not be dangerous since you will not be able to draw any current of significance via this route - but if not tied to a good earth you will feel it.

You may have a poor earth connection to the house. You may have poor earth continuity between the TD/WM socket and the CU.

Did you actually measure this with a resistance range on the DMM rather than just the continuity bleeper range (the latter will bleep on any resistance less than the bleep threshold - and this is often tens or even a couple of hundred ohms)? You want a fairly accurate measurement of the resistance between socket earth terminal and main earth point at the CU taken with the DMM set to its lowest ohms range. The result should be well under one ohm.

Chances are its fine - but don't always assume that as it came from the factory will work! I bought a new CU once that would have shorted the main supply had it been connected in the as supplied state!

Reply to
John Rumm

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Ok John, (and others: Dave, Adam)

Have hit reply to your post and included quote original, so hope you get th= is as expected. I am using the NEW Google groups UI so maybe that has something to do with = it, or is it your end? No one else has mentioned having problems following = this thread... but I used to build websites so I know how many variable can= be at play to ensure all see what you want them to see!

Pictures speak a 1000 words, so I have put this diagram together to help sh= ow my floorplan and location of all the components in play... you should be= able to see it here:

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me know if there's info missing.

Deano

Reply to
deano

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> Let me know if there's info missing.

Nice picture mate.

I still suspect some sort of bad earthing at the "blue" sockets in the utility room and I still would not ignore the possibility that the house earth is not up to scratch.

Cheers

Reply to
ARWadsworth

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Thanks, I used to be in the design biz so drawing's my thing :)

Yes.. blue sockets definitely at play here AND note your caveat about the h= ouse earth.

Is there anything I can do before calling in someone with the right kit? i.e. are there other appliances in a house that I can use the DMM on to tes= t or repeat what's been happening with the cabinet? One good method of faul= t diagnosis I use, is to try and repeat the results on similar apparatus an= d setup - not just for electrical systems.

deano.

Reply to
deano

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