New Junction Box with 3 spurs

[labarnes]

Hello

I'm in the process of converting a large spare bedroom into 2 rooms (an office and a spare bedroom). In doing this, I want to add a few more sockets into the office.

I've take some of the floor boards up to reveal the Ring Main cables. What I want to do is use the existing single plug socket as the main feed and branch 3 spurs off of it. I'm happy to branch one spur off of a ring main socket, as I've read this is ok, but I'm reluctant to branch 3 spurs. I think I should be using a new junction box in place of the original single plug socket and then branching 3 spurs off of the junction box; 1 to feed a new single socket in the original spare room and the other 2 for new double sockets in the office.

I will need to power about 14x 5-13Amp applicance, so I want this all to be safe. I am tempted to get this done professionally, but have no idea how much it would cost. I'm sure I can do this all myself, but as the JB and cables will be under the floor boards, I want to get it right and safe first time around!!

I've uploaded a diagram to iron out any confusion:

Untitled

• labarnes
• 5 May 2009
• 2

or try:


Cheers!

 

[kkynaston]

JB's need to be accessible for testing and tightning so no to concealed JB's.

Edit: and no you can't run more than 1 spur

As you have the boards up can you not extend the ring.

Ie, where the current socket is move one leg to one socket and the other leg to another socket on the other side, the connect between them thus keeping the ring intact

 

[mattylad]

Are you not able to pull the existing ring out and extend it to the new sockets to encompass them in the ring?

 

[ericmark]

If you down load this at the end there are diagrams showing all you are allowed to do.

 

[AndrewDavie]

While technically you could use an FCU instead of a junction box,
in this case I wouldn't recommend it as it would be confusing for a later maintainer as the sockets wouldn't be in the same room let alone the same location.
Extending the ring circuit is the best idea.

 

[labarnes]

Thanks very much for the prompt replies. Really appreciated.

I just been out to buy some 1.5mm2 10M cable (3 core with Max rating of 240V 16 amps 3840 W). I will proceed with extending the ring main.

I know that it DEFINITELY is a ring main, but do I need to check whether this original single socket is already a spur? I seriously doubt it is, as only a few sockets in the house and they're all untouched from new (30 years!!).

Thanks again

 

[Chri5]

You need 2.5mm and in all seriousness adding on to 30 year old wiring without testing it first is a bit silly.

 

[PrinceofDarkness]

It's evidently too much to expect, 'lab' that you have the wherewithal to test that circuit. But at least you could check the the two cables at the now redundant socket are both live by separating them and checking each with your 99p neon screwdriver.

If they both 'seem' to be live, then one of those cables should be taken to the new single socket in the bedroom and the other cable to the nearby twin socket in the 'offfice' (each cable is likely to be long enough to do this, since those outlets are close to your proposed siting of the join box).

From each of these sockets, use a 2.5mm cable to feed the second socket in the office, thus restoring the ring-continuity, and thus keeping all connections 'above floor'.

If you don't do it this way - with the properly sized cable (coordinated to the circuit protection device), then you'll be a very silly boy.....


Lucia.

 

[JonoPashley]

Thanks very much for the prompt replies. Really appreciated.

I just been out to buy some 1.5mm2 10M cable (3 core with Max rating of 240V 16 amps 3840 W). I will proceed with extending the ring main.

I know that it DEFINITELY is a ring main, but do I need to check whether this original single socket is already a spur? I seriously doubt it is, as only a few sockets in the house and they're all untouched from new (30 years!!).

Thanks again

From that description i assume you bought it from a diy shed and paid through the nose for it.

 

[labarnes]

Damn. I asked some "expert" in the aforemantioned DIY shed (orange logo) and he said this 1.5mm2 would be fine as it's designed for Electric Fan assisted ovens.

Before I return for a refund. I assume also that I will need a greater Amperage then 16Amp, as the ring main fuse is 30Amp. Right?

Cheers again!

 

[Taylortwocities]

Before I return for a refund. I assume also that I will need a greater Amperage then 16Amp, as the ring main fuse is 30Amp. Right?

Correct, your added cable will be carrying the total current for the ring. So yes, this will be more than 16amp. Is the ring final fuse is 30amp? We cannot see it from here...

The posts above have already told you what the cable size must be.
Hope you bought some green and yellow sleeving too?

 

[kkynaston]

Did the 'expert' have a pizza face?

 

[bongos]

Damn. I asked some "expert" in the aforemantioned DIY shed (orange logo) and he said this 1.5mm2 would be fine as it's designed for Electric Fan assisted ovens.

Worrying. Very worrying.

Before I return for a refund. I assume also that I will need a greater Amperage then 16Amp, as the ring main fuse is 30Amp. Right?

Correct. Incidentally 2.5mm² is only appropriate for your 30A fuse because it is connected in a ring. This is why it is important to make sure you still have ring continuity when you finish.

You've already know more than the DIY shed 'expert'

 

[ColJack]

every single person in an orange shirt is a glorified shelf stacker and should be treated as such.. it's fine to ask them where stuff is, but don't ask for technical advice...

as an aside, think it might be worth hanging round in B&Q with my navy blue electricians shirt on and tout for work?