Loft sockets question

[archee]

Hi fitting a a couple loft sockets on a radial circuit.

I only have 2.5mm cable and really don’t want to buy a reel 4mm2 is it ok to use on 32A mcb if I put a fcu before the sockets as it will never exceed 13A and the cable is rated for 27A.

Or is it better to add another separate 16A breaker and just run it off that ?

P.S I might run a light into the airing cupboard below off this circuit too will put a 3a fcu.

Thanks

 

[ERFspark]

It may carry 27A clipped direct, assume you have applied any necessary correction factors if applicable? Any thermal insulation? Ambient temperature? etc
No idea why you would use a 32A MCB to feed two sockets especially two that wont have much loading on them. Fusing it down in the loft metres downstream does not really make this arrangement acceptable
You can buy cable by the metre in loads of places, either get some 4mm or better still, downrate the MCB to 16/20A. No need to fuse it down then. Also make sure there is additional 30mA RCD protection.
There is a logical thought process I see from your post above, but it wouldnt comply with the regulations.

 

[ERFspark]

That being said, if you’re doing DIY on your own house you can do what you like. If it was me certifying it, I wouldn’t install it like you suggested.

 

[archee]

It may carry 27A clipped direct, assume you have applied any necessary correction factors if applicable? Any thermal insulation? Ambient temperature? etc
No idea why you would use a 32A MCB to feed two sockets especially two that wont have much loading on them. Fusing it down in the loft metres downstream does not really make this arrangement acceptable
You can buy cable by the metre in loads of places, either get some 4mm or better still, downrate the MCB to 16/20A. No need to fuse it down then. Also make sure there is additional 30mA RCD protection.
There is a logical thought process I see from your post above, but it wouldnt comply with the regulations.

Makes sense. The reason I asked about 32A MCB is because on my CU there are 3x32A 1x20A and the rest 3 x 6A for lights. And I have one spare 32A mcb saves me buying one.

I will do that then, will buy a 16A and run it off that, thanks.

Thank you

 

[archee]

That being said, if you’re doing DIY on your own house you can do what you like. If it was me certifying it, I wouldn’t install it like you suggested.

Nah I rather listen to you doing DIY doesn’t mean I don’t want it to be safe and a crap job. Mainly why I ask for advice in the first place.

Thank you very much

 

[ERFspark]

Makes sense. The reason I asked about 32A MCB is because on my CU there are 3x32A 1x20A and the rest 3 x 6A for lights. And I have one spare 32A mcb saves me buying one.

I will do that then, will buy a 16A and run it off that, thanks.

Thank you

Certainly the best option. Good luck

 

[Lucien Nunes]

Unless the cable runs through thermal minsulation or is derated to an Iz of less that 20A e.g. due to high temperatures, use a 20A breaker. The 20A radial feeding sockets via 2.5 sqmm cable is one of the standard recognised configurations.

 

[ERFspark]

You can have whatever configuration you want, providing it complies. Hardly think anything close to double figures in current will be drawn from two loft sockets.
Incidentally, do people still wire socket circuits as rings? Can’t remember the last time I installed one. It’s funny people still think they have to wire all sockets in a ring.

 

[nicebutdim]

You can have whatever configuration you want, providing it complies. Hardly think anything close to double figures in current will be drawn from two loft sockets.
Incidentally, do people still wire socket circuits as rings? Can’t remember the last time I installed one. It’s funny people still think they have to wire all sockets in a ring.

I'm yet to meet anyone of that opinion. Some might prefer ring final circuits to radials, and vice versa, but I imagine most have the ability to discern where one would be more appropriate than the other.

 

[davesparks]

I'm yet to meet anyone of that opinion.

Oddly enough I have encountered the 'sockets = ring' mentality a couole of times.

The most bizarre one was as an apprentice when my mentor had installed a dedicated ring for a bank twin sockets next to each other in a cupboard.
I questioned why he didn't run it as a radial and he said something along the lines of that if it's more than one socket then it should be a ring.

 

[Markyd]

Dont forget if your running in a new 20amp circuit will need a EIC and notifying to building control also the RCD will need upgrading if its a type AC