Home electrical ring main.

[Firestop]

I wish to make an extension to my house ring main. The connection will be below ground floor level (Wooden floor has cavity beneath). What type of connector should I use? I also want to run a spur from this to a fused switch. Can I connect this spur using a three way junction box beneath the floor?"

 

[stem]

Junction boxes cannot be installed where they cannot be accessed for inspection. So unless you have a cellar below the floor in question that will allow access, it's a non starter.

You need to use an accessible connection point, such as a socket.

 

[ColJack]

junction boxes are not allowed under floors, all connections must be accessible for inspection.

if you are extending the ring then you replace the cable between 2 sockets with 2 cables and connect the extension part to that.

fused spurs should be incorporated into the ring where possible, and in this case it is possible because you are extending the ring

are you aware of Part P of the building regulations and are you aware of the BS:7671 electrical installaton regulations?

 

[ban-all-sheds]

Junction boxes should be accessible for inspection & testing.

If you have access under the floor why can't you extend the ring to run to the new sockets and the FCU without using any JBs?

[EDIT]That'll teach me to answer the phone in mid-post & then not check that nothing has changed since I started...[/EDIT]

 

[Chri5]

Untitled

• Chri5
• 23 Mar 2010
• 1

Best bet is to break in to nearest socket, and drop a cable down and under the floor from there.

Then you have ring in, ring out, and the new spur out cable all terminated together on the socket and no junction boxes.

You can have a junction box under the floor, but it must be accessable. Some might argue that a loose floor board section could be an access trap, problem is that 75% of floors will have a underlay and carpet cover, 15% a sealed floor system such as tiles, laminate or hardwood, and the rest natural floorboards sanded and sealed. So the latter type could be accepted.

Junction boxes are considered bad because they are a potential problem point a) because it is a junction b) because they used to be hidden everywhere (in walls, under floors) that was near impossible to get to c) the 50Hz frequency could (apparently) cause vibrating to the screw terminals in the j/box which over years might loosen the terminals

 

[ban-all-sheds]

Best bet is to break in to nearest socket, and drop a cable down and under the floor from there.

Then you have ring in, ring out, and the new spur out cable all terminated together on the socket and no junction boxes.

If you have access under the floor to the circuit cables then you have no need of any spurs - put the FCU onto the ring, properly.