Fused spur off a ring main cable size question

[truckster]

As I already said" Appendix 8 of the OSG gives advice on standard cct arrangements for households. It goes on to say "cct arrangements other than those detailed in this appendix are not precluded when specified by a competent person"

 

[Hawk81]

Yes but this is a standard A1 ring final as specified and therefore only one non fused spur should be taken from it.

 

[Gerry wall]

I think this is a FUSED spur and NOT a NON FUSED SPUR.

Gerry

 

[Hawk81]

I was refering to truckster's advice to take a 4mm non fused spur to do the 2 sockets

 

[Gerry wall]

Ok Sorry mate

 

[truckster]

Yes it is a standard cct now but by using a 4mm spur only makes it non-standard, not wrong.

 

[Deleted member 9648]

Yes it is a standard cct now but by using a 4mm spur only makes it non-standard, not wrong.

I would tend to agree....as long as it was properly designed and executed. The problem is what starts out as 2 twins on a 4.0mm spur might escalate into a whole radial on said spur.Thats why we have the one point per unfused spur guidance,makes sense in my opinion.

 

[Deleted member 9648]

I would like to mention something here chaps but as far as I am aware you sohuld not be using 1.5 T/E cable in a ring main period. When you spur off you should use 2.5 T/E cable. If you were spuring off to a lighting circuit then from the spur you would use 1.5 T/E but beofre the spur 2.5 T/E.
As already mentioned the load would be way to much under these conditions. Just look at your appliances and add up the amps needed and you will find it is way more than 13A.
Once you have spured off you can add as many sockets as you like within under the regs but again you have to work out what you are going to plug into it.

Best bet would either be to extend the ring main or run a new cable from the consumer unit.

Hope it works out

Gerry

The OP was asking if it is acceptable to use 1.5mm on the load side of a FUSED(13a) spur....which if you refer to the BRB app 15 you will find can run an unlimited number of sockets.
It has already been pointed out that in the circumstances a fused spur,either 2'5mm or 1'5mm will not supply the proposed load.

 

[mickys86]

I was refering to truckster's advice to take a 4mm non fused spur to do the 2 sockets

I definitely agree.
If you are taking a spur from a ring, you can only have one double socket at the most. But if you are coming of a FCU then it's unlimited amount bearing in mind that your limited to 13amps.

And someone mentioned about not being able to use 1.5mm? As has been said previously. You have fused the circuit down to 13a and (off the top of my head) 1.5 can take around 26a

 

[mickys86]

The best option is to open the ring.

 

[mickys86]

I definitely agree.
If you are taking a spur from a ring, you can only have one double socket at the most. But if you are coming of a FCU then it's unlimited amount bearing in mind that your limited to 13amps.

And someone mentioned about not being able to use 1.5mm? As has been said previously. You have fused the circuit down to 13a and (off the top of my head) 1.5 can take around 26a

Ok its 20a ref method c
Even ref method a is 14.5 and it's still higher than 13a

 

[Maddermanblue]

Thanks for all the advice, somewhat turned onto a healthy debate.
Am I right thinking that the BS7641

 

[Maddermanblue]

Ignore what I just posted, iPhone playing up and sent it prematurely...
As I was trying to say is it correct to assume the BS7671 book is open to interpretation?
Anyhoo, it's all change now, they can't make their minds up... It's been decided the washing machine and tumble drier is to go in the extension currently being built.
I am going to spur off the ring main for the 2 new sockets using a fcu, and use 2.5mm t/e no heavy loads are going to use it.
The extension is part of the kitchen, only a separate room, is ok to extend the kitchen ring main into the extension? It will house a tumble drier and washing machine and possibly a fridge.

 

[johnelectrician]

I really dont get why you dont just extend the ring main using a 30a junction box?

 

[Farmelectrics]

Why not extend the ring