Earthing

[FrankTrent]

I've just had a new boiler and the electrician said that my Consumer Unit is out of date as 17th Regulations mean a new one will have RCD's. I raised the subject because I wanted to know whether my bath (which is all concealed plumbing) might be earthed. Electrician said A new CU would provide total protection as current would cut before it had time to kill me. Is he right ? (and is £500 a reasonable estimate)

I'm terrified of electricty as in one house, there was a faulty earth on the Immersion (toddlers had pulled it out of connection) and when the element deteroirated, I could feel shocks from W machine and whilst in the bath .

 

[ban-all-sheds]

Remember though, this only actually happens for a very short time because if the casing and sink are bonded together then (99.9 times out of 100) there will be an effective path to earth which will trip the breaker very quickly (in domestic situations to 17th). You actually have to be holding the radiator and touching the casing while the fault develops.

It was like that before the 17th.

The reason for the limits on EFLI is to ensure that the breaker will trip before a L-E fault can raise an exposed-conductive-part to a dangerous touch voltage.

 

[bernardgreen]

Electrician said A new CU would provide total protection as current would cut before it had time to kill me. Is he right ? (and is £500 a reasonable estimate)

No he is not 100% right.

If you get an electric shock then the RCD in a new CU may operate but only if enough current flows through you from Live to Earth to trip the RCD. It is still possible to die as a result of an electric shock that the RCD did not react to. Some will be electrocution but many deaths are consequential, like falling off a ladder as a result of the shock and dying from injuries from the fall. And if the RCD has cut the lights and/or the phone that needs mains power to work then getting help may be delayed to be too late to save the life.

 

[Taylortwocities]

I've just had a new boiler and the electrician said that my Consumer Unit is out of date as 17th Regulations mean a new one will have RCD's. .

Your consumer unit complied with the regulations at the time it was installed.

New regulations have come along but they do not apply to existing stuff. So yes your consumer unit doesn't comply with the new regs but that is not relavent.

What is important is that new work has to comply with the new regulations. Unless there has been a lot of major work done it is unlikely that this will mean a change of the consumer unit. Can you say what work this electrician did (or will be doing) for you?

 

[kevindgas]

all that is required is that the circuit worked on is brought up to standard.

there are a couple of ways this can be done

1 new consumer unit - expensive option
2 RCBO fitted in existing consumer unit - if unit capable of having one
3 RCD switch fitted instead of Fused Connection unit for the boiler - around £75 fitted.

 

[Taylortwocities]

all that is required is that the circuit worked on is brought up to standard.

there are a couple of ways this can be done

1 new consumer unit - expensive option
2 RCBO fitted in existing consumer unit - if unit capable of having one
3 RCD switch fitted instead of Fused Connection unit for the boiler - around £75 fitted.

Or nothing at all if the circuit is (for example) already RCD protected and the electrician was trying to punt for an unnecessary consumer unit change

 

[FrankTrent]

Thanks.
The rising main is earthed and so presumably, if there are no plastic pipes I could assume that effectively all the other copper pipes and metal appliances are earthed and that I only need worry if there are plastic pipes which put appliances beyond the earth ?
but even then, I can't see how i would get any electricity into the bath with me unless it leaked in through the water, but I understood that even if that happened, water is a poor conducter and the current would be very slight.

 

[bongos]

If you are able to post a pic of your exisiting fusebox/service head then people will be able to give an idea of how outdated your existing installation.

The rising main is earthed and so presumably, if there are no plastic pipes I could assume that effectively all the other copper pipes and metal appliances are earthed

Have you got a metallic gas or oil supply for heating? These also require a protective earth bond back to the main earthing terminal.

 

[ban-all-sheds]

The rising main is earthed and so presumably, if there are no plastic pipes I could assume that effectively all the other copper pipes and metal appliances are earthed and that I only need worry if there are plastic pipes which put appliances beyond the earth.

I'm afraid you've got that the wrong way round.

It's not earthing in the bathroom, it's bonding, and it's when the pipes are copper that you need it. If they are plastic, or if there's a reasonable run of plastic before the bathroom, then you don't need bonding.

Bonding & plastic pipes.

 

[martinxxxxxx]

Hi there

If he said you must upgrade the Cu he would be wrong to say that. It will provide additional protection if it is upgraded and the main bonding would be included in the price (which is very reasonable)

My twopennth over

Martin

 

[FrankTrent]

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• FrankTrent
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• FrankTrent
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Image 2 shows the earthing to the stopcock.
the earth goes across the house and is then earthed into the C U (the earth cable is actually behind the white cable in Images 1, 3, &4).
Image 1 shows the other earth running from the main gas supply to the CU.
The other black pipe next to the gas supply is a disconnected gas supply.

Before the boiler was replaced, all the pipes in the boiler room were earthed together. now, the only earth is as shown.

The C unit has no RCD as far as I can tell. It was installed by 'a mate' who is an electrician in 2003 and it was then that he completed all the earthing, which has now been replaced by the single earth to the stopcock.

 

[JohnD]

I would very much like to see a closeup of the meter board, showing the incoming supply and company fuse, and the cables around and between them, especially any green and yellow ones

Also, is there a label fixed to the meter board saying "protective multiple earthing"?

 

[nozspark]

The C unit has no RCD as far as I can tell. It was installed by 'a mate' who is an electrician in 2003 and it was then that he completed all the earthing, which has now been replaced by the single earth to the stopcock.

If it was installed in 2003 then it is unlikley that it complied with the regs then,, unless you have RCD sockets for all sockets that could be used for outdoor stuff...

A better (closer) photo of the service head and CU would help though!!

 

[Steve]

The boiler appears to be protected by an RCD.

So his part of the installation complies with 17th edition.

 

[bongos]

Looks like the gas and water incomer have been bonded as required. These may not be the required sizes, although I don't believe that there has been a change in main bonding csa's since 2003 so they should be correct.

It also looks like you have a decent earth connection from the service head to the CU. It looks like you have PME (Protective Multiple Earthing - or TN-C-S). However, I hope that this was completed by the DNO and not your friend doing his own "TT to PME" conversion!

Anyway, a close up of the CU would help. Does the red coloured switch on the right hand side say something like "100A main isolator" or "30mA RCD"?