Has anyone run a radial main in 4mm2 T&E?

[The Jeep]

Has anyone run a radial main (supplying kitchen sockets and appliances) in 4mm2 T&E? Do common accessories (double sockets, fused connection units, etc) accommodate this size of cable OK?

 

[Adam_151]

BS1363 requires that they accept 3x2.5mm² or 2x4mm², some go beyond this, and you can terminate 2x6mm² in MK stuff (but that is a tight fit and I dare say you'd need a deep box)

 

[viewer]

Hi, I've used 6mm with Crabtree sockets without problem. As Adam said, the size of the backbox is the limiter as it's not that easy to bend. HTH

 

[Lectrician]

I do it often in commercial kitchens - 2 sockets per circuit, so one has to loop in/out. I use standard 25mm boxes most of the time for flushed ones, and use MK MCO fronts.

It's the sensible way to go

 

[The Jeep]

Thanks for that, guys. I got the 4mm2 T&E today and it looks fairly workable. I'm using 35mm back boxes and, as it's a radial, will only have one coming in and one going out on everything except the last one in the chain.

 

[RF Lighting]

Why not, for the sake of it put in an extra cable and make it a ring?

 

[scousespark]

Why would you opt for a ring over a radial. Apart from the smaller cable.

 

[ban-all-sheds]

Why would you opt for a ring over a radial. Apart from the smaller cable.

Well - let's see.

More complicated to test.
Problems and possibly danger with branches added in the future.
Breaches to the integrity of the ring, and therefore safety, not apparent via non-working sockets.
The need to specially craft wiring regulations to allow the use of 2.5mm² cable on 30/32A protective devices.

There may be more reasons, but I can't think of any right now....

 

[Lectrician]

I always find numpties extending a 4mm radial with 2.5....strictly speaking it's no different from spuring from a ring.....but it's wrong

Rings are ok for domestics, 4mm is fairly expensive. I still use rings for domestics, but for commercials, I always opt for radials.

 

[The Jeep]

I have to run the cable through very restricted space in a loft, so I reckoned running one cable would be less work than two! Also, all the accessories will be behind tiles, so there will be little likelyhood of spurs being added.

Anyway, I haven't used 4mm2 before, so it'll be a new experience...

 

[ebee]

you could wire a ring in 4.0 or 6.0 if yer wants

 

[ban-all-sheds]

You could, but how would you determine what breaker to use?

 

[ebee]

use the same calcs as you do with 2.5 (66% each leg for current etc)

 

[ban-all-sheds]

You need to get up to speed on changes to the wiring regs - that's no longer in there...

I'm not saying that it's wrong, but it is no longer a compliant method, so you're into departures from BS7671, and possibly trying to persuade a numpty inspector at some point of the validity of your electrical engineering calculations....

 

[plugwash]

and its not as if there is really much point in having a socket circuit over 32A anyway at least not in a domestic situation.