DIY Doctor

Ring Main

Postby mondial34 » Sat Dec 29, 2007 4:22 pm

Hi Everyone

What a great forum.

I have a question/s regarding the ring mains in the house I have moved into as currently my wife has me putting up new light fittings everywhere. :roll:

The ring main uses grey cable with a red and black within. All the old light fittings have one black cable going to the brown on the light fitting and another 2 black wires going to the neutral on the light fitting, the reds which I would take as the lives are connected together by wiring blocks, this is my first confusion ?

This does not pose a problem connecting the new light fittings as I connect them just as the old ones were but, all the new light fittings say that they must be connected to earth but I have NO earths coming out of the ceiligs just the red and blacks connected which were connected to the old light fittings, is this a problem ?
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Postby BLAKEY1963 » Sun Dec 30, 2007 1:06 am

sounds like your wiring is dated.
u would need to get in an electrician to look at the age of the
wiring and possibly test it. and then go from there.

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Postby 333rocky333 » Sun Dec 30, 2007 2:37 am

You are unlikely to have a ring MAIN. for the lights.

A Ring CIRCUIT for the sockets and
A Radial Lighting CIRCUIT for the lights

The reason for the joined reds is they are PERMANENTLY LIVE from the fuse/mcb and the black wires being used for both L and N is the method used for wiring from the switch to control the light,this is called three plate wiring and usually found in a ceiling rose or behind the fitting.

You will proberly see a drawing etc explaining how it works in the project section.

As blakey says your wiring is out of date.
And you will need someone to assess it.

If the wires are twin it is likely other stuff like bonding etc is also outdated and all this has to be put right before even starting on the rewiring.

This could be a major problem that needs adressing BEFORE you
decorate or lay carpet etc, as you will most likely need the lighting circuits rewiring unfortunately.

Any metal lighting fittings or metal switches requiring earth, if fitted would be potentially dangerous as they MUST be earthed.

It was normal practice many years ago to do the lighting with twin AND NO earth cable.

Unfortunately the lights you have put up ,or metal switches, if the instructions say require earth and you have not done so, regardless of what was there before, although working may become live in a fault and highly dangerous unless they are specifically made to not require an earth.
This also includes any fitted by previous owner

You may have to stick with plastic switches and plastic ceiling rose pendants and fancy lampshades until you can get lighting wiring upgraded.

The instalation was originally safe years ago as the lighting was all plastic ceiling rose /pendants and plastic switches which at that time did not require an earth present.

Nowadays an earth wire must be provided at every lighting point and switch even if not required at present.
Except in rare exceptional circumstances

Any electrical test you have now would most likely fail for this reason.

If you want nice lights you need twin and earth cables installed for that circuit.
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Postby ericmark » Sun Dec 30, 2007 2:46 am

Blakey1963 is right not sure when we started to use earths with lights but all my houses have had earths but many I have worked on have not and I have had to change all the light fitting for those not requiring earths until a rewire could be done. If an earth is not required it has two squares one inside the other on it and normally no metal. I was unable to find florescent fittings that were double insulated and very few pretty ones.
Lights are not normally on a ring main. Normally a spur i.e. there will be an end of line somewhere.
The earth must run with the supply cable you can't just run earths you need to change cable. I know that has been done in the past but if no earths then you may have rubber cable not PVC and rubber does not last that well. Plus it has not been used for a long time so in most cases if rubber cables are found a rewire is required.
Since you have just moved in you should have the electrics inspected and tested anyway. If your house then pity you moved before the information pack thing came in but if rented then the landlord is required to have the inspection and test on change of occupancy.
Not really a DIY job the meters required to test cost too much about £700 for the set. So cheaper to get an electrician to test than buying meters and it's another 10 years before next test is required.
Earths may be missing else where I have tested some houses and found no earth at all where originally it relied on water pipes which have been changed for plastic in the road.

All best Eric

Postby stevenc1603 » Mon Dec 31, 2007 4:27 pm

Check the grey cables and see if they are twin and earth that has had the earth snipped off. The earth would be unsheathed so you don't see any colour, therefore it can be hard to spot as it will just be a small copper end.

If they have been cut off then whoever did the installation should be shot. You might be lucky and have enough slack in the cables to allow you to expose and use the earth, however your next problem would be that it might not be connected to anything at the consumer unit.
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Postby juli-juan » Wed Jan 02, 2008 9:25 pm

what are the sockets and switches like if switches are round with toggles it might have rubber cables see if fuse board looks old too better still call a sparky he will tell you best course of action as all metal lights switches need to be earthed. did u get a corgi gas man to your gas fire and heating so get a NICEIC sparky 4 your electrics. its horses 4 courses
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