Confusion in the Consumer unit

[gazmo30]

I live in a victorian house which was propably re-wired in the 80's. What i can't understand, with my limited knowledge of electrics, is how it is wired. In the CU i have a 30amp fused marked ring power. This feeds 2 double sockets in the lounge, 2 doubles in the dinning room and all the sockets upstairs. I also have a 15amp fuse marked 'power lounge & dinning' which serves one double socket in the lounge. Does this sound correct?? Is it possible for somebody to explain the ring power as the last socket in the dinning room only has one wire running to it!! Should the last socket not run back to the CU??

FYI there are also fuses for the kitchen, lights up, lights down, immersion heater and cooker.

 

[breezer]

its a radial socket.

see the wiki for more info

 

[davy_owen_88]

The socket with only one wire could be a spur from the ring circuit, or it could be incorrectly labelled and actually be a radial circuit.

Ideally you should have one fuse for upstairs sockets and one fuse for downstairs sockets, but over time additions are made, bits are removed and it becomes the mess you have there today.

Is there a problem that has prompted you to look into the electrics or are you just curious

 

[gazmo30]

Thanks for the propmt reply. Can the power ring be a radial circuit?? From looking at the site, i thought a 30amp fuse meant it should come back to the CU?

 

[davy_owen_88]

Thanks for the propmt reply. Can the power ring be a radial circuit?? From looking at the site, i thought a 30amp fuse meant it should come back to the CU?

Depends on the cable size used. If it is run in 4mm² twin and earth then a radial can be protected by a 30A fuse.

 

[gazmo30]

No problems, none of the fuses have ever blown, but we are going to decorate and could do with some further double sockets added. So i am curious as to why there is only one socket on the fuse and wondering if more sockets can be added safely!!

++++++++++++++++++++++++++++++++++

no all the cable is 2.5mm2 twin and earth

 

[davy_owen_88]

It will be safe to add more sockets but only when you have a thorough knowledge of how everything is wired.

You have a 2.5mm² radial protected by a 15A fuse - this is fine and you can add more sockets from that socket.

You have a socket in the lounge with only one wire going to it. If you can verify that 'ring power' it is actually a ring circuit then that socket is a spur and no further sockets can be powered from it. If it is not a ring circuit and is run in 2.5mm² cable it is incorrectly labelled and incorrectly fused and should be changed to 15A.

Do you have a multimeter with continuity function?

 

[gazmo30]

Sorry, i have confused the situation. The 'power lounge & dinning' 15amp fuse only serves one double socket in the lounge. And i assume this is a radial circuit as it only has one wire to it. Can i also assume that further sockets can be added to this?

Yes i do have a mulitmeter with continuity function

 

[davy_owen_88]

If you are sure the socket in the lounge is powered from the 15A fuse and is not a spur from somewhere else you are free to add as many sockets as you like from it.

If you want to check that the 'ring power' circuit is actually a ring then take out the fuse, check the circuit is dead and do a continuity test between between the 2 cables. If there is no continuity and the cables are 2.5mm² you either have a break in the ring (check every socket and tighten up the terminals) or you have a radial which is incorrectly fused and should be replaced with a 15A fuse.

 

[didthathurt]

Or even a 20Amp fuse provided the cable does not pass through insulation or does not need any other de-rating. If you are going to extend the radial you refer to I'd also replace that 15Amp fuse carrier with a 20 Amp version. As RF would say, though, a pic of the board and the fuses might just give us a little more info to go on.

 

[gazmo30]

OK, thanks for all the help so far. It makes me more at ease regards the 'power lounge & dinning' circuit and that more sockets can be added safely. I am still a little concerned by the 'power ring'. In an ideal world i assume that all the circuits in the lounge and dinning room should be on the 'power lounge & dinning' fuse. Is it worth getting all the sockets in these two rooms onto that fuse and making it into a ring circuit??

I will also test the 'power ring' to see if it is a ring circuit and change the fuses.

 

[didthathurt]

Is it worth getting all the sockets in these two rooms onto that fuse and making it into a ring circuit??

That depends on what it would entail from a house bashing point of view and what you aim to power from these sockets. There's nothing at all wrong with a radial circuit - the rest of Europe uses them extensively. I prefer to install a 2.5mm radial to kitchen refits for the fridge and freezer power, for example. If 20Amps is enough (gives you about 4.5kW to play with) and, IMHO unless you plan to use a couple of fan heaters it probably will be, don't fix what ain't broke.

 

[gazmo30]

OK, two more questions to really set my mind at ease. If i want to add a few more sockets in the dinning room, can i run a new cable from an existing socket and add a spur (the dinning room sockets are fed by the 30amp 'power ring')?

If i want to add more sockets in the lounge, can i create a radial circuit from the existing 1 double socket which is on the 15amp 'power lounge & dinning' circuit?

 

[davy_owen_88]

If i want to add a few more sockets in the dinning room, can i run a new cable from an existing socket and add a spur (the dinning room sockets are fed by the 30amp 'power ring')?

If you have ring continuity there should be 2 cables at every socket. If there are 3 or 1 then it is not a suitable location to take a feed for more sockets.

There can only be one un-fused spur from a socket, and you can not spur from another spur. Fitting a fused spur rated at 13A allows you to power as many sockets as you chose from the load terminals.

If i want to add more sockets in the lounge, can i create a radial circuit from the existing 1 double socket which is on the 15amp 'power lounge & dinning' circuit?

Yes. Use 2.5mm² twin and earth.

 

[gazmo30]

Thank you davy_owen_88 and didthathurt for your help.