Adding a spur for a projector - How to do it?

[TenaciousJohnny]

Hi,

I am looking to add a new mains socket for my projector which is high up a wall. Ideally I would create a new socket near the projector & run a spur off the nearest socket. However, I have already run a spur off that for another double socket & my B and Q DIY book says I shouldn't run 2 spurs off 1 socket.

As an alternative, could I change the existing spur to be a single socket, & then run a second spur to another single socket for the projector?


TIA

Johnny

[durko]

One spur only mate.

Best, safest and only way is to break into original socket and continue as a ring main.

To do this there will be 2 main wires going into original socket forming part of the ring main, pull one of these wires out and add a junction to this wire (round brown junction one suitable for high amps) connect mains twin and earth wire to this junction and run to first socket, another wire out to the second socket and another wire from the second socket back to the original socket.

This if you get my jist forms a circular ring (ring main)
The only issue you will have is that you will have to burry the brown juction box into the wall.

[durko]

Here an image of a ring main to give you a visual how it works. You just need to break into this and continue the ring, you could even do it from upstairs if you can gain access through the floor boards as the wires will be there directly above where the sockets are downstairs

[dpeaco]

Alternatively............

Is that original socket part of the ring circuit? - If it is, the fuse or breaker will be 30 or 32Amps. If not, the circuit will be a radial circuit, the fuse will be 15 or 16A and then there will be no restriction on the number of sockets you can add.

If it is a ring circuit, you could add a fused spur to the circuit, then you would be allowed to add 2 sockets. Go back to the original socket on the ring that you fed your new socket from. Disconnect your new socket then connect a fused spur instead. That new socket and your (even newer) one for the PJ can both then be fed from the load side of the fused spur.

Only downside is that you will be restricting the load you can place on your two new sockets to 13amps (the size of the fuse in the fused spur). Depends what you run from the other socket as to whether thats a problem for you.

The regulations do require you to protect any new sockets you fit with an RCD. Perhaps your existing circuit is RCD protected back at the consumer unit? If not, use an RCD protected fused spur instead of a standard fused spur.

[TenaciousJohnny]

Thanks a lot for the advice guys. Much appreciated. I'll get a junction box tomorrow & do it properly

Johnny.

[durko]

Best way Johnny
If you do it this way you get used to how your property is wired up and when you want to add more sockets anywhere in the house you just ring main it.

Go down the spur route and think what you house wiring would look like and more important fire risk.

[dpeaco]

Durko is right, extending the ring is always best, but its not always easy, hence my alternatives.

By the way - we NICEIC registered electricians do not suggest methods that would pose a fire risk!!

Even if you extend the ring you still need to ensure the new sockets are RCD protected (as I said, the ring may already be RCD protected back at the board).

[mr ooops]

sorry to but in, im wanting to do same thing, how much would a trusted sparky charge, one ive had in to quote wanted £200

[dpeaco]

Depends on how much work is involved - how far away is the new socket location from the nearest usable socket, is it a stud wall or is channelling into plaster required, are you expecting making good afterwards or doing that yourself, will an RCD be required or is the circuit already protected, is the earth up to scratch?

In the worst case scenario £200 would not be excessive. If its easy with no RCD required £60 might cover it.

Worth remembering that a registered electrician will test the circuit fully, identifying faults that may already exist, rectifying these if necessary, confirm the circuit is safe, advise you on whether your earthing and earth bonding is up to scratch, and leave you with paperwork which effectively makes him liable for any safety issues arising from his work in future.

You get a lot more for your money than some people realise!

[TenaciousJohnny]

Hi,

I've added my new socket to the mains ring & it works. Thanks for the advice everyone.
Re. Mr Oops question, about his quote, seeing what I had to do, I would have been happy to pay £200. I have solid brick walls. I had to create the hole for the new socket, lift a floorboard for the junction box, & create channels in the plaster. It took me many many hours.

Anyway its finished & I have one more question.The plasterer is coming on Monday to skim the room & fill in all the holes I have been making.
I was thinking that I would remove the new socket plate so that he has easier access to fillin the holes round the back box. If I do that, is it safe to leave the bare wires exposed, if I wrap them in insulating tape? or do I need to attach them to some sort of terminator?

TIA

Johnny

[reevesy]

safe......as long as the mains...or the circuits trip switch is off!

you could do this then fit some correct amp rated terminal blocks.....you could then have the mains on and be reasonably safe.....just let the guy know about it.

.....just another thing before the plasterer skims over have you fitted a metal strip/protector over it?..........not esential but 1 will give a bit more long term protection to the cable......plaster i think will corrode the cable a bit over the years? (many years probably?)....but more importantly if anybody in the future forgets it's there and drills into the wall.....bang.....at least when you hit metal you know somethings wrong.........
or do what i did....drill into the wall and hit metal......thinking it was the frame i had put up a few years ago......changed the masonary drill bit for a metal one and kept drilling!......
bang! and much swearing and calling myself a silly so and so.

[TenaciousJohnny]

Hi,

I was planning on putting the metal capping on top of my new channel, but the plaster is pretty thin at some places on the wall, & it barely covers the cable as it is. Really can't be bothered increasing the depth of the channel by going into the brick if I don't have to. It was hard enough work chiselling out the holes for the back boxes for the new sockets & speaker cable outputs!!

Is it really bad practice, to plaster straight on top of the cable? Was going to do the same with my long HDMI cable & speaker cables.

Cheers,

Johnny

[dave2506]

My understanding of this mate is that as long as the cable is in a permitted zone (i.e. within a vertical or horizontal straight line from the socket) then capping is not required although is normally considered good practice for the reason outlined before. It is only if you choose to run a cable in a non-permitted zone (diagonally for example) that there are rules outlining how deep it must be buried and for capping etc.

Also, modern plaster will not corrode modern electrical cable so you are fine to plaster directly over it and this will probably also be fine for your HDMI and speaker cables (although you may want to consider running them in conduit in case you choose to change them at a later date).

Please note though that I am not a qualified electrician, my advice is purely from personal experience of having to do similar work in my own house a few months ago. All of this type of work is governed by the Part P Electrical regulations so if there is anything you are unsure of I would suggest consulting that first

Hope this helps!

[TenaciousJohnny]

Dave,

Appreciate your advice & that it is not "qualified".
My cables are all running in straight lines so I think I'll just run with it. I've got all the cabling in for HDMI & 7.1, so I'll take the risk that if something new comes along, I'll have to rip it out.

Johnny

[davehk]

Originally Posted by TenaciousJohnny

Hi,

I've added my new socket to the mains ring & it works. Thanks for the advice everyone.
Re. Mr Oops question, about his quote, seeing what I had to do, I would have been happy to pay £200. I have solid brick walls. I had to create the hole for the new socket, lift a floorboard for the junction box, & create channels in the plaster.
TIA

Johnny

Unfortunately, JB under floorboards does not comply with the wiring regs as all screw terminal connections have to be accessible for inspection and test (yes I know the regs are not statutory).

That's why it's better to spur off the ring from an existing socket, or to extend the ring between two existing sockets. You can also replace a single socket with twos ingle sockets on a dual back-box and the extend the ring from there, if there is no other convenient socket to get the other leg from.

Originally Posted by dave2506

My understanding of this mate is that as long as the cable is in a permitted zone (i.e. within a vertical or horizontal straight line from the socket) then capping is not required although is normally considered good practice for the reason outlined before. It is only if you choose to run a cable in a non-permitted zone (diagonally for example) that there are rules outlining how deep it must be buried and for capping etc.

Hope this helps!

Regarding capping - capping is used to protect the cable during plastering, that's all. It does not provide sufficient mechanical protection for cables run outside the safe zones and buried <50mm deep (from either side of the wall!) - you have to use proper EARTHED steel conduit or cable such as SWA with earthed armouring. Even for cables in the safe zones, the 17th edition of the regs requires these to be RCD protected if buried less that 50mm deep (from EITHER side of the wall - though this is academic for 13A sockets anyway as all sockets <20A have to be RCD protectd regardless) though conduit etc is not then needed.