Loft Sockets.

[SirKit Breaker]

I have a job coming up to replace existing batten fitting in loft with a 6ft Flourescent tube, no problems there, not altering anything, its on the existing house lighting circuit protected by a 5a rewireabe fuse. Zs and IR of circuit well within spec.

Customer wants 6 off twin switched sockets in loft all surface mount to floor to power his model railway set up, max demand on circuit of about 4 amps on a bad day, he only wants so many so as to not have extension leads all over the floor. He doesnt want any decorating or mess if avoidable in the house.

The CU is Wylex with 8 rewireable fuses, Ze and all the other basics etc are all Ok on a TNC-S supply.

In the airing cupboard in the bathroom there is a disused 2.5mm T&E cable which is fed from a 15a rewireable fuse (old immersion heater supply), I have tested the cable and it is fine IR of 233meg, Zs cant remember but it is well in spec. This cable is not accesible between CU and Airing cupboard. The CU is at ceiling height in cupboard which is conveniently directly below the Airing cupboard. The cable is only exposed for the 4 or 5 feet it is clipped to the door frame.

I intend to reuse this cable, but put it in plastic trunking. Then extend the cable into the loft as a radial. Total length of circuit from CU to last socket is about 8 metres.

At the point where i extend i am going to fit a shower CU in the airing cupboard, with 40a 30ma RCD incommer and a 60898 16a MCB.

Am i missing anything, is it compliant? Comments and opinions please good or bad.

I will also replace the rewireable fuse with a plug in 15a 60898 MCB just for convenience. There are plans for a CU upgrade but not until funds allow.

Cheers...........Howard

 

[MWE]

hi mate just reading youre thread,everything sounds good but just not with you on the 40a 30mA incomer when only being fed from a 15A breaker(obviousley sockets need to be rcd protected) but is there not a suitable rcbo to feed the sockets????? Although would 4mm cable need to be used if just a radial

 

[rocker]

I would say that this is probably because shower units tend to come with a 40A double pole RCBO, it is often easier and cheaper to use this as the RCD protection and put a smaller breaker in for the MCB protection.

 

[monkeyelectric]

Can't see a problem with that myself but an rcd fused spur may be a better option, put the spur in the cupboard where the cable ends then up to the loft to your sockets

 

[pevvers]

Although would 4mm cable need to be used if just a radial

No need for 4mm cable if the current carrying capacity of 2.5mm after correction factors can take 15 amps. In a domestic, I doubt you'd find enough correction to warrant a 4mm radial on a 15A, but who knows!

 

[DurhamSparky]

sounds well... what sort of sad person collects model trains lol....... oh yeah i do.. lol

 

[billy110]

Here here.

Sorry, that was a here here to the rcd fused spur!

 

[SirKit Breaker]

Can't see a problem with that myself but an rcd fused spur may be a better option, put the spur in the cupboard where the cable ends then up to the loft to your sockets

Good idea, why didnt i think of that! Just goes to show know matter what you know, or how long you have been doing it there will always be an easier way.

Cheers....................Howard