2.5mm on 32A MCB

[kingeri]

Just wondering what folks would do if you came across this on your travels. 4mm radial sockets circuit, on 32A MCB. Two branches from the CU, one supplying 6 double sockets, wired entirely in 4mm, so fine. The other branch consists of a 1m run of 4mm to a double socket, then around 5m in 2.5mm cable on to a second double socket.

The question is, who would be happy to leave this arrangement in place, and who would downgrade the breaker to 20A? I would say it's ok, as the 2.5mm can't be overloaded as it feeds only one double socket, just like an infused spur off a ring.

 

[telectrix]

be fine as it is.

 

[kingeri]

Thanks Tel. Still don't know why they didn't just use all 4mm though, talk about penny pinching.

 

[telectrix]

maybe it was a sunday. or wholesalers 20 miles away, or wholesaler wanted to sell him 100m when he only needed 1m.

 

[7029 dave]

IMO okay, not much difference than a spur off a RFC IN 2.5mm.

 

[hightower]

As others have said, sounds similar to a spur off a rfc so can't see an issue with it. I wanted a bit 4mm yesterday, Screwfix don't even stock it - it's a next day item. Not to mention I've just bought a nice shiney new circular saw, opened it up, doesn't even come with a blade. Bah humbug.

 

[Wilko]

In bah humbug mode - I think the max length by reg xyz is 3m

 

[westward10]

Nope wrong in my eyes especially when someone sticks another point on it. What cable is the 4.0

 

[Wilko]

In bah humbug mode - I think the max length by reg xyz is 3m

I think it's reg 433.2.2
My thought would be to add another 20A mcb and move the 4/2.5 radial onto that. Win win?

 

[kingeri]

Nope wrong in my eyes especially when someone sticks another point on it. What cable is the 4.0

What do you mean what cable is the 4.0? It's bog standard 4mm+1.5mm cpc T&E. Length 1m. If someone adds another socket from the 2.5 in future, that's their look-out.

 

[kingeri]

This isn't something I have installed, just to be clear.

 

[kingeri]

I think it's reg 433.2.2
My thought would be to add another 20A mcb and move the 4/2.5 radial onto that. Win win?

Yes, this is what I suggested in my OP, but the other branch is running some fairly big loads, which is why I wanted to avoid it.

 

[westward10]

What do you mean what cable is the 4.0? It's bog standard 4mm+1.5mm cpc T&E. Length 1m. If someone adds another socket from the 2.5 in future, that's their look-out.

Well 4mm could equate to many cable types.

 

[grandfortune]

nothing wrong with it, if someone want to add to it later he has to upgrade it, apart from that its been installed correctly

 

[westward10]

nothing wrong with it, if someone want to add to it later he has to upgrade it, apart from that its been installed correctly

Poor practice, but there you go.

 

[Toneyz]

if you look at Fig 15B BYB it shows a 32a 4.0mm radial with a unfused spur to double socket via j.b. wired in 2.5 .I would rather like to see it in 4.mm or on own 20A prothctive device.

 

[westward10]

I will C2 it all day.

 

[kingeri]

I will C2 it all day.

Which reg is it contravening?

 

[westward10]

The cable is not suitably protected against overcurrent, this is how I see it.

 

[The Ghost]

In design terms cable must carry less than or equal to the protective device. i.e. 32a protecting a 17a ccc does not meet this criteria. Look up Ib In Iz and try not to make me do it please Dammit...433.1.1