Re-use of outdoor SWA cable - notifiable?

Richard M · Sep 30, 2019

Hi - I hope someone can advise on this.

So we had an old shed knocked down and replaced with a wooden barn with its own proper electrical supply.

The SWA mains cable that used to feed a small distribution board in that old shed just happens to run near my summerhouse. At the house end of that cable it feeds into its own circuit breaker on the house distribution board (with shared RCD protection with other breakers) - and this was all re-wired with modern equipment in about 2010.

Question: am I allowed, as a DIY'er, to feed that SWA cable into my summerhouse, connected to a double-socket?

Remember: the cable was originally wired from the house's distribution board to an outdoor shed. So all I'm doing is moving the cable from what used to be the shed's own distribution board to a new double-socket in the summerhouse.

I've seen that adding a new circuit is notifiable - but here I'm re-using an existing circuit.

Thanks for any advice.

Richard

binky · Sep 30, 2019

Hmmm, it may not be a new cct, but you are changing the 'electrical chracteristics' of the cct in a notifiable area of work. Plus it sounds like you havn't got RCD potection at the house end?

2 points:-

1/ have you terminated SWA before?

2/ if there isn't an RCd at house end, you could use an RCD socket in greenhouse.

3/ socket in green house needs to be an outdoor type IP44 rated - greenhouses get damp and tend to be occuped by insects and snails.

Richard M · Sep 30, 2019

Thanks for the quick reply.

1. I've used armoured network cable before - and the electrical version looks very similar.

2. The house end is RCD protected. The house distribution board has about 4 or 5 breakers per RCD. The cable described is on one of those breakers.

3. It's a summerhouse made of wood - the socket would be inside.

Evans Electric · Sep 30, 2019

Binky said "Greenhouse " , I'm sure I read about some new Regs for greenhouses but this is a summerhouse , I just looked .

You have RCD protectioin at the house , you need to buy an outdoor cable gland (CW) to match the cable size , you need an IP rated socket and the circuit breaker needs checking to protect the cable .

Its up to you to be honest , there will always be DIYers , any members on here would be testing the socket to ensure adequate earthing & .....not sure ... probably fill out a Minor Works Cert . As to notifying Building Control who knows , who cares .

I'll be finishing a new garage supply later this week and will notify it as a new circuit . I never found out what Building Control actually DO with all these notifications.

I do know that at the start of the scheme my council was deleting them in their thousands as they had no storage & retrieval system in place I presume .

Doc Hudson · Sep 30, 2019

You have made no mention of what size CSA the existing cable is. What the rating of protective devices supplying is, What the length of the cable run is, what the new expected load will be in the summer house compared to the old shed or if you have suitable equipment to test the earth continuity, insulation resistance, earth loop impedance, or RCD operating characteristics etc.

Your argument that it is not notifiable is dubious and could be debated either way. Like for like replacement of existing wiring following faults/maintenance is not quite the same as re-instating some old physical wiring to supply a new location that previously didn't have any electrical supply. But reality is that unless you are doing the property up for immanent sale, it is unlike anyone would question it. Did you have electrical certificates and Part-P compliance certificates for the previous work in 2010? If you do the old certificate may just say "outdoor circuit", which is very open for debate anyway.

However irrespective of the notifiable aspect, the work should be done to the current edition of BS7671 wiring regulations, and would still need an appropriate electrical certificate issued to confirm it is safe and compliant. If I were doing it, for the minimal cost I would probably notify it anyway. And I would make sure it is NOT off a shared RCD with circuits in the main house. Nothing worse than losing half the house power when something goes faulty up the garden.

Doc H.