junction boxes & ring main

[climberjim]

Hi,

I understand that its not allowed to extend a ring main with junction boxes. Is this because the wires are more likely to be pulled out of a junction box than a socket. I ask because where a socket has been added to my ring main the ring main was cut completely (i.e. not just the earth wire) and then re-joined - is this allowed?

Secondly why is it allowable to put a double socket on a spur since 2x13A appliances could overload a 2.5 cable (would it be better to use thicker cable or run 2x2.5 cables in parallel from the main to the spur).

On a separate note does any one have any tips for making holes in the underside of floor boards to gain access to the cavity of an plasterboard wall.

Thanks Jim

 

[bussiebuss]

its ok to extend a ring main with junction boxes as long as the ring doesnt exceed 100m2 and you use 30amp jb's

it is ok to join any cable as long as it is accessable to inspection or repair if a fault occurs

it is ok to put a double socket on a spur because the double socket is protected with a 13amp fuse in the spur so if you as you say pluged in two 13amp appliances drawing 13amps each then the fuse would blow remember you are only protecting the cable

best thing to do is just extend the ring for the new double socket and do away with the fused spur
for the hole cutting problem

http://www.diy-hardware-store.co.uk/screwfix-90369.php

 

[breezer]

not sure if the poster meant spur or a twin socket as a spur.

and junction boxes although you can get them are no longer supposed to be used, crimps are . (but i would go go for the 30 jbs)

 

[spark]

Where did you hear that idea breezer? I too have been told that, just wondered if it was the same source

 

[breezer]

here

 

[spark]

Well I'm pretty sure that's not in my reg's book, and I've got a pretty good grasp of it. I think it's a case of Chinese whispers, especially as it looks as if that info came from a builder. The experience I had was with the NICEIC rep who said JB's were not acceptable for use when connecting downlighters etc because they did not have cords grips . Again it's interpretation of the reg's; in my opinion JB's are fine if they are correctly connected and installed.

 

[climberjim]

not sure if the poster meant spur or a twin socket as a spur.

Breezer,

What I mean't was twin socket as an unfused spur. i.e a single connection from junction box/socket on ring to a double socket (am I right in thinking this is allowed?). Thus the wire from the sockets to the ring main could have to take 26A. In terms of current I can't see the difference between this and going from the ring main to a single socket and then onto another single socket. As it happens in my case the wires pretty much in free air for its length and would probably take 26A. Just seemed to be a little illogical. However if JBs are out for adding spurs as well as extending the ring I might as well use a second one and be hung for a sheep.

and junction boxes although you can get them are no longer supposed to be used, crimps are . (but i would go go for the 30 jbs)

.

What exactly are crimps, are they basically the spade or bullet type connectors you get in a car.

Many Thanks

Jim

 

[il78]

Junctions boxes are fine to use as long as you can gain access to it (526-04-01) other than that use crimps in the JB.......

 

[breezer]

climberjim, crimps are what you see in a car, but slightly different. they look like

but the standard crimper is not good enough you should use one like

its a ratchet crimper and does a better job