How do I know if I've got a ring circuit or a radial circuit?

[lilimop]

Hi!

Is there any way to know if I have a ring or a radial circuit in a division of the house?

Thanks!

 

[Markyd]

Yes get a sparky in to test

 

[cliffed]

A ring circuit you can test continuity on Live Neutral Cpc conductors @ the CU or @ the power points.
Radial circuit checking r1 r2 by linking these conductors @ the end of the radial circuit

 

[pc1966]

In most cases if the supply breaker is 32A it is an RFC, and if 20A/16A a radial. But there can be exceptions to that by design, or by someone (typically builder or DIY) breaking an otherwise good design.

If you have a socket out (power off and tested to be off obviously!) with two sets of wires at the back of it and you isolate them there, then if measuring L-L or N-N you see a low resistance of under a few ohms then it is almost certainly an RFC.

Measuring CPC-CPC (earth - earth) should also form a loop, but in is not uncommon for the CPC of circuits to be linked elsewhere back to the main earth terminal, such as at a boiler, so that test is not as reliable as checking L-L and N-N.

If you find one of L-L & N-N is linked but not the other then you have a fault somewhere to be found and fixed!

 

[Mike Johnson]

Radial circuit has only one wire coming out of the CU from the MCB usually, a Ring circuit has two, but this does assume there are not two radials on one MCB.

 

[timhoward]

Radial circuit has only one wire coming out of the CU from the MCB usually, a Ring circuit has two, but this does assume there are not two radials on one MCB.

That is the key word!
The breaker size sets expectations.
The number of wires set expectations.

But ultimately only testing confirms what is actually the case.

 

[Mike Johnson]

That is the key word!
The breaker size sets expectations.
The number of wires set expectations.

But ultimately only testing confirms what is actually the case.

I have always been an optimist.