Minimum distance for spur junction boxes

[Adam75]

Hi

I want to add another junction box spur to a ring main. There is already a junction box with a spur in the area I wish to add another one.

Is there a minimum distance the junction boxes need to be apart.

The existing spur is a single 13amp single socket & I wish to add a double socket.

Thanks
Adam

 

[PrenticeBoyofDerry]

Why don't you extend the ring?
Junction boxes also need to be easily accessible!

 

[Adam75]

extending the ring main means channelling in 2 2.5 cables in the wall.

I only really need a spur, but thanks anyway

 

[JohnW2]

extending the ring main means channelling in 2 2.5 cables in the wall. I only really need a spur, but thanks anyway

True, but if the socket is to be on a wall, that will presumably mean chanelling in one 2.5mm² cable? I presume from what you say that the existing JB is part of the ring. If so, you could extend the ring from that JB (probably adding a second one), without having to disturb the wiring to any existing sockets.

Anyway, the short answer to your question is 'No' - there is no minimum distance between junction boxes on a ring, just as there is no minimum distance between sockets. To be compliant with regulations, the junction box(es) would need to either be accessible for inspection and maintenence or else be of a 'maintenance-free' type. However, avoiding JBs is always the 'preferred' method.


Kind Regards, John

 

[PrenticeBoyofDerry]

There is no minimum distance between junction boxes, but extending the ring is best way to go, chasing out for an addition 2.5mm cable is not that greater task in the grand scheme of things!

As already mentioned if the joints are to be hidden and not easily accessible, you can only make that joint by use of special techniques or the use of MF boxes, a standard junction boxes will not be compliant to BS7671.

 

[JohnW2]

The other point which none of us have yet mentioned is that, to be compliant with regulations, the new socket would have to be RCD protected. If the existing ring is not already RCD-protected, you would need to either get the whole ring protected or use an RCD-protected socket for the new one (or feed the new socket through an RCD FCU).

Kind Regards, John

 

[PrenticeBoyofDerry]

The other point which none of us have yet mentioned is that, to be compliant with regulations, the new socket would have to be RCD protected. If the existing ring is not already RCD-protected

Oh burger! did I not mention that? Normally my favourite bit of info!
That and the permitted safe zones of cables buried within walls and the holing of joists.
But if you have not got enough time/effort to facilitate for 2x2.5mm cables, would really have time to be reading up on that?

 

[JohnW2]

The other point which none of us have yet mentioned is that, to be compliant with regulations, the new socket would have to be RCD protected. If the existing ring is not already RCD-protected

Oh burger! did I not mention that? Normally my favourite bit of info! That and the permitted safe zones of cables buried within walls and the holing of joists.

Yes, I did think that you had 'let yourself down' on this occasion! For myself, I have to say that I feel a bit silly (on behalf of the regs!) telling people that, to achieve compliance with regs, they need to RCD protect one new socket, but can leave the dozen (or whatever) existing sockets on the circuit unprotected!

But if you have not got enough time/effort to facilitate for 2x2.5mm cables, would really have time to be reading up on that?

Quite so.

Kind Regards, John

 

[PrenticeBoyofDerry]

Yes, I did think that you had 'let yourself down' on this occasion!

I can only humbly apologise.

For myself, I have to say that I feel a bit silly (on behalf of the regs!) telling people that, to achieve compliance with regs, they need to RCD protect one new socket, but can leave the dozen (or whatever) existing sockets on the circuit unprotected!

Tiss the nature of BS7671:2008

 

[JohnW2]

For myself, I have to say that I feel a bit silly (on behalf of the regs!) telling people that, to achieve compliance with regs, they need to RCD protect one new socket, but can leave the dozen (or whatever) existing sockets on the circuit unprotected!

Tiss the nature of BS7671:2008

Indeed it is - but it's such aspects which are bound to engender a little 'contempt' as regards the regs. I have no problem in encouraging people to get a whole sockets circuit protected (even though not required by regs) as a matter of safety - but, as I said, feel a little silly telling them that regs require them to RCD protect one (out of many) sockets on the circuit! People are far more likely to comply with regulations/rules/laws if they regard them as 'sensible'.

Kind Regards, John

 

[Adam75]

Thanks for all the help, I think I'm going to extend the ring main off the existing JB. The main is already rcd protected

 

[PrenticeBoyofDerry]

Thanks for all the help, I think I'm going to extend the ring main off the existing JB. The main is already rcd protected

It would be wise to if possible remove the JB all together out put a new length of cable between sockets.
If this is not practicable, then swap the existing JB for one of these...
http://www.tlc-direct.co.uk/Products/ASJ803.html