Ring or Radial Cable Question

[IsaacNewt]

Hi,
I wonder if anyone can give me some advice. This is a long post for what ends in a short question, but I thought that by giving the whole picture that I might get some other pointers or explanation. Sorry for the length of post.

I’m replacing our kitchen units and want to add more plug sockets while I’m at it. The CU is an old fuse box (without any spare places). There are 2 x 30A fuses, one of which is dedicated to the cooker, the other appears to power all plug sockets in the (smallish 1930s) house. Based on this I’d assumed that my sockets were all on a single ring circuit that I could add to. ‘Plan A’ was to do this myself.

However, when I tested the two live wires in a plug, with my multimeter set to ohms, (with the 30A fuse removed) I got no reading (i.e. the same resistance when touching the wires to the terminals as when not). I thus guess that it must be a radial circuit (or that the ring is broken?) (I may be missing something obvious – I get limited resistance when the fuse is replaced). I think the wires in question are 2.5 mm. There is also what looks like a 4mm cable coming from the same fuse and ending in a single plug socket (if that has any relevance). I should also say that we recently bought the house from someone who did his tiling with bluetack and other such techniques, so I’m half expecting to find something odd.

I’ve read lots of forum posts and have noted the general advice that if you can’t tell a ring circuit from a radial, you should probably call an electrician. I am, however, on a tight budget and would prefer to only get a professional in once and only to do the stuff that he needs to do. I’m thinking that if I can chase all the wires in myself, it will a) save me money, and b) allow me to get on and fit the kitchen; only calling the electrician in to hook up my ‘trailing ends’ at a more convenient time.

Does this sound at all sensible? If so, do you think 2.5mm wire with all plugs connected in a daisy chain with two trailing ends would be my best bet, or do you think 4mm wire, maybe with a dedicated run to the plug that will take the washing machine?

Any advice will be gratefully received.

Many thanks,

Isaac.

 

[EFLImpudence]

To test for a ring.

Switch off main switch.

Separate wires at a socket.

On low ohms - probes to both lives then repeat for neutrals and cpcs (earths}

The readings for lives and neutrals should be roughly the same - depending on the length of the circuit, half an ohm for thirty three meters.
The cpc reading should be 1.66 times as much if 2.5/1.5.



From what you write, say about the installation and want to do it really would be a good idea to let an electrician have a look and discuss your plans.

 

[OwainDIYer]

comprehensive method of testing a ring final circuit is here

http://wiki.diyfaq.org.uk/index.php?title=Testing_a_ring_circuit

 

[ban-all-sheds]

Isaac - your inability to tell the difference between plugs and sockets does not inspire confidence.

You need to get an electrician engaged right now, and agree with him what he is happy for you to do - it is not a case of you installing cables and then getting someone else to connect them, it does not and will not work like that.

"The CU is an old fuse box". No RCD then? If so then no new chased in cables and no new sockets.

 

[ericmark]

To get a different reading with fuse in or out assuming off at the isolator something must have been left plugged in or switched on.

My son moved into an old house and first move was to inspect and test. He then could decide his next move but until that is complete it is impossible to work out what will be required.

In his case he moved wife and children into his mother-in-laws house pulled down all ceilings and installed all new wiring and central heating plus insulation and is now ready to replace ceiling.

OK a little drastic but once complete he will be done with DIY for years. Old shell but new house inside.

There are many ways to tattle in my case few extra circuits and RCD protection on all and emergency lights over stairs.

With my mother's house re-wire kitchen so remove load from original ring the latter being left in place.

But step one must be an EICR only after that is done can you assess the risks and formulate a plan and time scale to correct and modify to how you want it.

Not uncommon to have spur from spur from spur and the easy way out is reduce fuse to 20A. With my mother's house by re-wiring kitchen and wet room the load from rest of house will never reach the 20A limit.

But the meters required to do a EICR are not cheap even to hire and do require some skill so unless like my son you have a full test set then likely the best first step is to get an electrician to do a EICR (was called PIR) and then make your plans.

 

[IsaacNewt]

Thanks for the advice everyone,
Isaac.