rings radials and

[9lives1left]

I have just moved in and I have a new consumer unit with RCD etc however older wiring I suspect. It looks as if the consumer unit was fitted to have an electric shower which is the only other modern thing in the house.
I have one breaker that says sockets and one that says lights. When switching either off , I naturally lose power to the whole house sockets or lights.

Ideally I would put in another ring main for upstairs sockets. Currently I have about 12 double sockets around the house about 3 I am guessing are spurs because of the proximity. I have concrete floors and it doesn't look likely , but if its not much hassle and I can find a way of routing it I will do it.

I have now added an extension onto the house and someone knocked down what was there already and taped up the wire ends and left them sticking out of the wall. I cant actually remember what was there originally , but seem to remember a fluorescent strip light and and washing machine in there when I looked around. This makes me think that there was both lighting and socket power there. However...

Now the structure is built , I have looked at the wiring and there are just two wires of the same dia sticking out of the wall. it looks like 2.5 mm cable.

What does anyone think I may have here?

My thought is that perhaps this is either end of a ring main? and that the strip light may have been on a fused spur?
It doesn't appear possible to get to the lighting circuit in the next room , without ripping up expensive flooring.

My electric is still functioning however, so have I now got two radial circuits?

Baring in mind I would want 4 double sockets in the extension and three separately switched lights, what would it be best for me to do.?

If I have two ends of a ring main, should I :-

a) Extend the ring to cover the extension sockets and spur off three fused boxes for the lighting circuits.
b) Not join the ring (if thats what it is) and extend both of them to cover some new sockets each and some fused spur lighting so having two radial.
c) It may be possible to branch each end back to the fuse box so creating two rings. Is this easy?
d) or some other combination.

Can I run three lighting spurs off of three different sockets in the absence of a lighting circuit?

How to I check what I have (ring or radial)?

anyone's help would be appreciated.

 

[il78]

Extend the ringmain to cover your new sockets, you can check the ring by using a continuity tester (bleep tester, whatever).

If you cant get to the lighting circuit, get your suuply from the ringmain using a unswitched fuse spur...then goto a 3gang switch to control your lighting...

Hope this helps

 

[9lives1left]

Thanks

Would that many sockets be considered to many on one ring?

Can I have more than one appliance off of one unswitched spur?

(I have 2 sets of lights I want on independant dimmers and one cant go on a dimmer.)

cheers

 

[il78]

number of sockets are fine....usually 1 appliance to 1 fuse spur but it depends on the rating etc.

you may have trouble in finding a 3 gang switch with 2 dimmers on....you will have to use grid type switch's..

 

[ban-all-sheds]

Re the extension - try the following:

1) If you haven't, just check that the unterminated wires in your extension are part of your ring main in some way - i.e. do they go live/dead simultaneously when you switch the MCB? BTW - suggest you fix some choc-blocks to the ends (not connect them together) to make testing with a multimeter or neon screwdriver safer.

2) Unplug the loads from the sockets, of at least most of them.

3) Switch off CU, remove cover and remove one of the cables coming from the "sockets" MCB. Insulate the end well, and tuck it somewhere safe. A clothespeg can be a useful device to hold it out of the way.

4) Switch on the CU.

5) Check all of your sockets with a plug in lamp (inspection, table, whatever, unless you have one of these) - if they all work then you have a ring with two spur cables going to your extension.

6a) If they don't all work, and one of your bare wires is live, and the other dead, then you have got 2 radials which have been created by breaking the ring at the point of the wires in your extension. You can double check this by joining the ends of the wires together, and seeing if all of your sockets are now live. Then disconnect the join (see test at step 8 )

6b) If they don't all work, but both your bare ends are still live, or both are dead, then you have 2 radials which may or may not have been created by a break in the ring somewhere else.

7) In the reverse order of 3) & 4), reconnect the cable at the MCB.

8 ) If you do have one of these just quickly check that none of your sockets have L/N reversed. V. unlikely, but as you're going to be joining your wires, it wouldn't hurt to check.

9) If you had 6a, you can either join those wires in the extension together, to reinstate the ring, or extend them off to other sockets (remembering the 100sq m rule) and back again to make a complete, extended ring.

10) If you had 6b, you need to find where the break is, and resolve it, as 2.5mm cable is too thin for a radial (assuming the MCB protecting it is 30/32A).

 

[9lives1left]

Thanks Ban-all-sheds

Why do 3? are you talking about a Live coming in from the meter?

It sounds good , although i dont have one of those meters. I am armed only with the trusty neon screw driver. (one owner and slightly melted).


Whats 8 ? and how does that happen?

cheers

 

[ban-all-sheds]

Why do 3? are you talking about a Live coming in from the meter?

Depends which bit of (3) you mean. Disconnecting one of the wires that comes out of the MCB is so that you can see if you have a ring - if you have, all the sockets will still be live, if you haven't those on the radial that you've disconnected will be dead. But if you do have a ring, then the end of the wire you've disconnected will be live, which is why it's a good idea to wrap some tape around it, and make sure is doesn't go where it's not wanted. Turning off the whole CU may be unnecessary - I don't know what yours is like inside, and if when you remove the cover the live busbar is exposed or not. If you've been there before, and you know there are no nasties awaiting a slipped screwdriver, by all means leave it on, but do switch the MCB off before removing the wire. Many CUs are designed so that you can't remove the cover without switching off anyway.

Whats 8 ? and how does that happen?

Sockets will work fine with Live and Neutral going to the wrong pins (but not as safely). If you're connecting the ends of two radials together to make a ring, you don't want to be connecting a live to a neutral, and vice versa, but your trusty neon screwdriver will confirm which are the live conductors - don't assume that they will be the reds, even though 99.99% of the time they will be. But that will show up when you do the checks at 6a). All you know is that a red wire leaves your MCB, you don't know if it is joined to a black one somewhere under your floorboards, but thinking about it, that could still happen without L/N reversal at any sockets anyway. So although checking them is a good idea generally, as you don't know how brain-dead the previous occupant was, it doesn't actually have any bearing on this.
Except that if you find that one of your blacks is live, now would be an excellent time to remove all the sockets and find where it needs putting right

 

[breezer]

"neon tester" screwdrivers are very usefull......... for undoing screws, they can only tell if i live is present not a neutral, if you intend to carry out any electrical work i suggest you get a decent multimeter

 

[9lives1left]

Thanks you, I shall try all of this and if no one hears from me again, you will know that it didnt work out !

 

[9lives1left]

It all worked fine first time following your methods.

Brilliant !


Thanks very much !

cheers