13A socket off 32A radial (old immersion heater cable)

[koniosis]

Multimeter shows no voltage across any of the 3 sets of wires. I feel uneasy about just cutting them off and stuffing them back into the wall. Any advice?

Also, with all 12 wires disconnected eveything works (lights, sockets etc). So definetly not lighting wiring.

I had a closer look at the radial wire for immersion heater, cable just says "RISTS F 300/500V / BS6004 BASEC" looks like 2.5mm to me.

 

[koniosis]

Garymo has a point, you can spur off a ring with 2.5mm2 with the ring having a 32A CB, why is it different for a radial?

 

[Steve]

Garymo has a point, you can spur off a ring with 2.5mm2 with the ring having a 32A CB, why is it different for a radial?

A radial can have lots and lots of sockets on it.

A spur can have ONE double or single on it. As both double and single sockets are theoretically limited to 13 amps total, its safe. In reality a double socket CAN draw 26 amps, but its still OK, since the cable's maximum load is 27 amps (optimum conditions)

 

[GaryMo]

Steve, this radial is limited to one twin socket, just like a spur off a ring final.
Same protective device, same CSA of conductors.

What's the difference?

 

[koniosis]

Turns out the cable from the cupboard is actually on a 6A MCB which has no label on it. I have no idea what the 32A MCB "Immers Heater" is for now.

 

[ban-all-sheds]

Garymo has a point, you can spur off a ring with 2.5mm2 with the ring having a 32A CB, why is it different for a radial?

Ring.

That's why you can have a 2.5mm² on a 32A breaker - the current drawn at each socket is shared between two cable runs from the CU.

http://www.tlc-direct.co.uk/Book/6.3.2.htm

 

[GaryMo]

We're not talking about the ring conductors, it's the spur conductors which we're comparing to a one twin socket radial fed from a 32A protective device.

Imagine a ring final supplied from a 32A protective device which also has a spur feeding a twin socket. This spur originates from the 32A protective device in the consumer unit.

So, what's the difference?

The similarities are that both scenarios have a twin socket wired with 2.5mm2 conductors (not a ring as one is a radial and the other is a spur) and both are fed via a 32A protective devices.
Both are capable of consuming 26A.

The difference is that two other conductors (ring) share the same terminals as the spur in the consumer unit but neither of those conductors share current with the spur.

 

[ban-all-sheds]

Gary, you ask questions like "what's the difference?" and then answer them in a way which makes it really hard to work out what your concern really is, or what point you are trying to make.

If the point is that there's no difference between these:

1. A 2.5mm² spur from a socket on a ring final
2. A 2.5mm² spur from the MCB of a ring final
3. A 2.5mm² radial from a 32A MCB supplying one socket outlet

them yes, there is no difference.

In which case, so?

 

[GaryMo]

The is no difference, that's the only point I'm making.

No agenda only that it's accepted when originating from a ring but is greeted with a gasp of horror when a twin socket radial is supplied from a 32A protective device.

Am I going on a bit?

 

[holmslaw]

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