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2nd Opinion (is a rewire required)

Postby Baza-C- » Tue Apr 07, 2009 2:05 pm

HI iam new to this forum and have been unable to find an answer to my question. I hope someone can help.

I have recently had the consumer unit replaced in my home and have been informed by the elctrician who did the work that my house needs a rewire. The elctrician that carried out the work informed me that none of my circuits are earthed and as a result he could not reconnect the lighting circuits. He has fitted a new unit that has the new RCD/MCB type fuses.

I am a little confused as he has managed to connect up the mains upstairs and downstairs as well as cooker. All the sockects(except one which casued the fault that prompted me to replace the unit are connected).

I have checked the lights and all the roses and switches have modern looking(it all looks the same to me) grey three core wire going to and from them. I am going to get another electrician in to give me a second opinion as I dont want my home to be unsafe and would like some advice on what I need to be asking in order to make sure I am getting the work done corectly

My questions are:

How can the mains circuit be connected & the lighting circuit not surely they both need to be earthed?

can the earth used for the mains circuit be used for the lighting circuit?

Can I correct the lack of earth in the lighting circuit without removing the existing three core cables and having to chase out all my walls. Is it possible to trace the cables and find out were they are earthed and connect this to the Consumer unit.

I know this is a very complicated area and just wanted some experienced people to give me an insight as to if it is possible to fix without the need for a rewire(as I am keen to avoid the mess involved with getting one done).

Many Thanks in advance for your help
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Simply Build It

Postby kbrownie » Tue Apr 07, 2009 5:35 pm

I'll try answer best I can.
How old is your house?
Way back, Electricians did not install a CPC(circuit protective conductors) what you are calling an earth to Lighting circuits.
This is perfectly safe providing accesories such as switches and light fitting are made of plastic or double insulated. (If metal then not so safe)
The power circuits for sockets and immersion heaters etc.. did have a CPC.
So your electrician has spotted this and flagged it up.
The regulation now require a cpc to be installed in lighting circuits and it would have been good of the electrician to inform you of this prior to fitting a new cu, they would have known this!
You can not use the socket circuit cpc for the lighting, it has to have it's own!
If you was to install a cpc for the lighting circuit, it makes sense to re-wire the whole circuit and just put cpc in!
You said you have three core cable for lights what colour are the cores?
what reason did you have for puttinfg a new cu in, not just because one circuit had a fault on it?

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Postby Baza-C- » Thu Apr 09, 2009 2:37 pm

Thank you very much for the information that now makes a little more sense. The house was built in about 1940 if that helps it has an extension built on the rear Approx 15 Years ago(lights connected and working in that section).

I Was told I needed a new CU by the electrician that told me I needed a rewire. The resaon I called in an electrician in the first place was because the main breaker switch would not turn off so I could not disconnect the power without removing the fuses. It had the old wire fuses 4x 30A & 3x 15A. He informed that this could not be repaied and should be condemed so I had to replace it with a new CU.

I will check out the color of the wires when I get home to confirm but from the circuit I checked it was a red a black and a green cable or mutilpes there of. I have just had the majaority of the house replastered and decorated so finding this out now is somewhat frustrating as i could have undertaken this work @ a later date. Rather than rewire the lighting circuit would changing the switches and light to non metal along with having a cpc connected to the existing wiring make the circuit safe(and Legal). Unfortunatley I am not in a pososition to be able to afford to have a rewire done and certainly dont want to have to redo all the plasterwork(there is no trunking).

If I have to leave the lighting circuit disconnected then I will just have to live without it.


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Postby collectors » Thu Apr 09, 2009 4:40 pm

Chances are you will get away with a rewire on the lighting only depending on the condition of the power circuits. If your house is pre 1965 with wooden floor boards, there is a good chance it won’t be that major to rewire as there is a very good chance of tube in the walls & if some chasing of new boxes in the wall is needed? Some finger plates can be fitted as a temp/measure to cover any mess around the switch plates.
Also as kbrownie was saying! Its not worth trying to get just an earth around the lighting just on it own, as its the same amount of work.
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Postby kbrownie » Thu Apr 09, 2009 6:30 pm

As it stands at the moment, any Metal Accessories ie switches and light fittings are best replaced with plastic. But wait till end of reply may be something here to give us hope.
I can understand why the Old Fuse box needed replacing as there was no means of isolation and you need that.
Last July the requirements for electrical installation got updated, to the 17th edition.
This included the requirements of RCD protection, so your electrician could not do a straight swap and would have been foolish to do so. but seems strange way he did not mention any missing CP Conductors as this is helpful in the function of RCDs
Now then, you say three core colours red, black and green.
Check the green cable see if this is a sleave that is fitted over a bare copper cable, good chance it is. CPC colours are now yellow and green used to be green though!
That could well be an CPC(earth) conductor, we need to know now if this conductor goes to switches, lights and to your CU on this circuit.
All circuits have to have there own cpc running with line(live) and neutral, sorry can't be pinching it from elsewhere!
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