Extending a shed lighting circuit Ask questions and find answers to many subjects relating to electrics and electrical work

[mobythevillan]

I've recently had the front of my shed/workshop extended, which had already been wired for power/lights. Now, I want to put an exterior light switch on the new front of the shed, from which I can control the two fluorescent striplights inside, but it means extending the wiring (1mm 3-core and earth) from the existing light switch.

It's a toss up between a junction box to extend the wiring, or just installing a new, longer run from the lights. I'd really appreciate some additional guidance from the more knowledgable here before I start cutting wires!

Thanks all,

Simon

[kbrownie]

mobythevillan,
I'd like to help but first I would like to know if you have any knowledge of approved document part p of the building regulations, because this area is considered a special locations the minor work you are wanting to do ie extending the circuit must be notified to building controls or a domestic installers scheme, full scope registered electrician must do the work.
It's a legal issue and could also make your house insurances invalid if not complied to.
KB

[mobythevillan]

mobythevillan,
I'd like to help but first I would like to know if you have any knowledge of approved document part p of the building regulations, because this area is considered a special locations the minor work you are wanting to do ie extending the circuit must be notified to building controls or a domestic installers scheme, full scope registered electrician must do the work.
It's a legal issue and could also make your house insurances invalid if not complied to.
KB

Hiya KB......many thanks for the info. I'm no electrician (as you've probably guessed by now), but can wield a mean screwdriver when I need to :)

Yes, I've heard of Part P, but was not aware of the precise limitations of the work allowed to be carried out 'DIY', as it were. I actually thought it applied to the installation of new circuits, and that light switches could be extended without being signed off. A little knowledge can be a dangerous thing huh?

From your comments, it looks like it's a job for 'the Man', but for information purposes only (ie when I contact the electrician), what would be easiest/cheapest/best, junction box or new run?

Thanks again

Simon

[kbrownie]

mobythevillan,
It's because of the location part p applies, if it was a bedroom, hall way, front room, dining room you could extend circuit without notification or needs for registered electrician but a minor works cert would be needed so need someone who can perform tests and fill the cert out for that too!
Special location and kitchens are bound by part p, even for minor work which extending circuits is considered to be, just about the only thing you can do in specail locations as diyer are replace accesories like for like.
Right the answer to your question.
If you are extending your sockets circuit you can extend by;
For radial circuit continue from very last socket-outlet on circuit using same size cable and add socket outlets from there.
If Ring final circuit you can extend the ring or easier option use a 13amp fused connection unit from socket outlet and add sockets from there, no restriction on number providing it's fused connection unit, you could add spurs but only one from each socket and you can't spur of a spur.
Your lighting i'd loop in from the last connection if that was possible depending on distance or take a 3amp fuse connection from a socket outlet to feed outside light. These circuit will require RCD protection.
But your sparks will tell you about that, junction boxes can be used as long as easily accessible for inspection and testing purposes so can't be buried in wall or in ceiling void.
KB

[mobythevillan]

mobythevillan,
It's because of the location part p applies, if it was a bedroom, hall way, front room, dining room you could extend circuit without notification or needs for registered electrician but a minor works cert would be needed so need someone who can perform tests and fill the cert out for that too!
Special location and kitchens are bound by part p, even for minor work which extending circuits is considered to be, just about the only thing you can do in specail locations as diyer are replace accesories like for like.
Right the answer to your question.
If you are extending your sockets circuit you can extend by;
For radial circuit continue from very last socket-outlet on circuit using same size cable and add socket outlets from there.
If Ring final circuit you can extend the ring or easier option use a 13amp fused connection unit from socket outlet and add sockets from there, no restriction on number providing it's fused connection unit, you could add spurs but only one from each socket and you can't spur of a spur.
Your lighting i'd loop in from the last connection if that was possible depending on distance or take a 3amp fuse connection from a socket outlet to feed outside light. These circuit will require RCD protection.
But your sparks will tell you about that, junction boxes can be used as long as easily accessible for inspection and testing purposes so can't be buried in wall or in ceiling void.
KB

Cheers KB, many thanks for the detailed info, and sorry for the delay in getting back to you!

When I get around to it, I'll mention this to my Sparks and take it from there. You may well have stopped me from burning my shed to the ground!

All the best

Simon