Bathroom - Shock!

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A N fault on PME would lead to the lights dimming every time you turned the kettle on and would be bloody obvious.

 
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It only happens on T N CS supplies that don't have an earth rod at the premises. It wouldn't happen in my country because all houses with PME'd supplies each have their own earth spike
as it should be,

I put my own rods in,

1 front at incomer, 1 rear where supply to shed leaves, and 1 at shed.  :D

 
...But somewhere hidden in a wall or beneath a floor there must be a connection from the current lighting earth to the earth of the ring main. This is going to cause all sorts of fun and games for RCD protecting the lighting circuit isnt it?

Another quandry.. how do electric/plumbed towel rails ever work? A fault could surely cause currently to flow back to earth through the HW pipe bonding (not through the CU) or back through the RCD protected circuit? Is the theory that both routes to earth would be paths of equal resistance hence enough current would flow back through the CU to trip the RCD? ..or should I stop thinking about this having far exceeded by GCSE electrics?
I suspect that you're thinking of the old voltage operated earth leakage circuit breakers (VOELCB). These became obsolescent more than 30 years ago.

Today's RCDs work by monitoring the current in line and neutral and tripping if the difference exceeds a threshold, often 30mA. They don't rely on the presence of an earth conductor (CPC) in the final circuit.

 
First electrician has been round to have a look. His verdict is the only problem is a lack of Earth on the lighting circuit. Proposed fix - replacement of 2 lighting circuits across 3 floors and new fully RCD protected CU. Explanation of live metalware in the bathroom - likely caused by a combination of no lighting earth coupled with some conductivity of the walls combined with notoriously inaccurate voltage pen.

 
A "notoriously inaccurate voltage pen" would not have given you a shock though. something did.

At least if you get the lighting circuits rewired that should be a step closer to being safe.

 
May aswell re-wire the whole house. RCD everything. And next door. That is also a step closer to being safe. OR - get a decent electrician in that can actually fault find.

 
First electrician has been round to have a look. His verdict is the only problem is a lack of Earth on the lighting circuit. Proposed fix - replacement of 2 lighting circuits across 3 floors and new fully RCD protected CU. Explanation of live metalware in the bathroom - likely caused by a combination of no lighting earth coupled with some conductivity of the walls combined with notoriously inaccurate voltage pen.
I don't understand, you have found a fault which could cause the symptoms you described if the lighting circuit was supplementary bonded to the water pipes (which it should have been, since there is no rcd protection to all circuits in the bathroom).The fact that the earth is not continuous in the lighting circuit is a problem, but only if you have metal fittings.

It could be that the earth cable has worked loose in just one fitting and it could be fixed.

The lighting circuit mcb could then be changed to an rcbo.

It just needs a bit of testing, surely.

Instead, you have been quoted 2 new circuits, with new fittings presumably, and a whole new CU. ££££

Let's hope the other sparky comes up with a cheaper alternative.

 
First electrician has been round to have a look. His verdict is the only problem is a lack of Earth on the lighting circuit. Proposed fix - replacement of 2 lighting circuits across 3 floors and new fully RCD protected CU. Explanation of live metalware in the bathroom - likely caused by a combination of no lighting earth coupled with some conductivity of the walls combined with notoriously inaccurate voltage pen.

erm... lack of earth on the lighting circuit wont give you a shock unless you have metallic light fittings/something that needs an earth, and its faulty.

you need to find someone who is competent at fault finding, not just re-wiring stuff in the hope of fixing the problem

'conductivity of the walls', never heard that one before....

 
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I don't understand, you have found a fault which could cause the symptoms you described if the lighting circuit was supplementary bonded to the water pipes (which it should have been, since there is no rcd protection to all circuits in the bathroom).

The fact that the earth is not continuous in the lighting circuit is a problem, but only if you have metal fittings.

It could be that the earth cable has worked loose in just one fitting and it could be fixed.

The lighting circuit mcb could then be changed to an rcbo.

It just needs a bit of thorough testing, surely.

Instead, you have been quoted 2 new circuits, with new fittings presumably, and a whole new CU. ££££

Let's hope the other sparky comes up with a cheaper alternative.

amended that for you!

 
I don't understand, you have found a fault which could cause the symptoms you described if the lighting circuit was supplementary bonded to the water pipes (which it should have been, since there is no rcd protection to all circuits in the bathroom).

The fact that the earth is not continuous in the lighting circuit is a problem, but only if you have metal fittings.

It could be that the earth cable has worked loose in just one fitting and it could be fixed.

The lighting circuit mcb could then be changed to an rcbo...
Indeed we do have 2 metal wall-lights in the bathroom. The casing screw on one had pierced the live which is, I believe, what caused the other metalware in the bathroom to go live. Having fixed the casing of the light - the taps etc are no longer giving me a shock / showing live.

The house is an edwardian property on 3 floors. There are 3 separate RCD protected rings for the sockets (1 per floor) and 2 lighting circuits (not RCD protected). 1 Covering the ground floor, 1 covering the top 2 floors. 

Throughout the house there are a selection of metal light fittings and metal switches with no earthing present on any of the lighting circuits. 

The bathroom lights and switch has an earth cable present.

The electrician who came yesterday had the view that the only way to resolve the problem was to add a proper earth to the lighting ring on the top floor. Regardless of whether this would fix the problem, this sounds like a sensible idea to me seeing as we are redecorating currently top-down. My question to him was whether a new circuit could be created for the top floor lighting and a new breaker added to the CU (plenty of spare slots). This would allow us to uprate the 1st and ground floors at a later date when we start the decorating there. His view was that he would be unable to do this since he could not sign off the work with the remaining 2 floors having no earth, and so he would only quote for 'all or nothing'. Is this correct? I thought that as long as the current system was being improved or made no-worse then that was basically ok?

Waiting on a time for the 2nd guy now :)

Once again - thanks all for your advice and guidance

 
Indeed we do have 2 metal wall-lights in the bathroom. The casing screw on one had pierced the live which is, I believe, what caused the other metalware in the bathroom to go live. Having fixed the casing of the light - the taps etc are no longer giving me a shock / showing live.

The house is an edwardian property on 3 floors. There are 3 separate RCD protected rings for the sockets (1 per floor) and 2 lighting circuits (not RCD protected). 1 Covering the ground floor, 1 covering the top 2 floors. 

Throughout the house there are a selection of metal light fittings and metal switches with no earthing present on any of the lighting circuits. 

The bathroom lights and switch has an earth cable present.

The electrician who came yesterday had the view that the only way to resolve the problem was to add a proper earth to the lighting ring on the top floor. Regardless of whether this would fix the problem, this sounds like a sensible idea to me seeing as we are redecorating currently top-down. My question to him was whether a new circuit could be created for the top floor lighting and a new breaker added to the CU (plenty of spare slots). This would allow us to uprate the 1st and ground floors at a later date when we start the decorating there. His view was that he would be unable to do this since he could not sign off the work with the remaining 2 floors having no earth, and so he would only quote for 'all or nothing'. Is this correct? I thought that as long as the current system was being improved or made no-worse then that was basically ok?

Waiting on a time for the 2nd guy now :)

Once again - thanks all for your advice and guidance
Not being able to sign off! What bull shxt. The electrician writes the description of the works the cert covers. Nothing more. Nothing less. Best you try another spark.

 
Installing a new circuit to resolve your immediate problem is a perfectly normal and reasonable course to take. Any person doing such works would certify the new items they have done, make some comments or observations on the certificate about the condition of the existing installation. Typically advise you of other recommended improvements that they notice whilst working on the installation. But there is no obligation to have to do all improvement works at the same time. Often peoples budgets do not allow this option. So staged work and payments are agreed to achieve a full improvement over a longer timescale. Doing smaller stagged work may actually cost move over the long run, but it may also be the only solution in may situations. You as the customer who is paying defines what level of work will ultimately be done.

Doc H.

 
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