how many 6mm2 wires in a standard terminal

[NikV]

Just moved - We have a 6mm2 radial (with 40A mcb) originally for an electric hob/cooker, the cooker switch/socket has been replaced with a double socket and the wiring continues to a double socket behind electric oven (one used for the oven). Nearby there is a single socket on the ring main which has 3 spurs off of it, one for a socket behind the fridge (normal 2.5 te) and two in flex buried in the plaster for sockets fixed in cupboards (wire just comes out of wall through back of cupboard into surface mounted pattress boxes with single sockets these are to be removed just leaving the single fridge spur) for the extractor and hob ignition circuits. I want to use the other gabg of the double socket behind oven for the hob ignition - should be no problem.

I want to chase up the wall and put a single socket for the extractor above the cupboards,

Plan A run a 6mm2 spur from the radial to the extractor socket

or

Plan B run a 6mm2 spur to a FCU(5A) and then 1.5mm2 to the socket (or

2.5mm2/13Afuse)

Can I get 3 6mm2 wires in a standard terminal on the back of the existing double socket???? How difficult will it be if possible, if not how can I do it.

opinions/help gratefully recieved

[Owain]

The electric oven still needs an *accessible* means of isolation.

bad bad bad.

Good.

You do not necessarily need to run the spur in 6mm. You can probably run in smaller cable from the 6mm to the FCU. The 40A MCB will provide short-circuit protection, and the 3A fuse in the FCU will provide overload protection. This must be proved by calculation however.

As well as the size of the terminal you have to consider the space inside the back box.

Good manufacturers will have technical info on their websites for their accessories which will include the cable capacities of the terminals.

Use a junction box on an accessible length of the 6mm cable between the sockets - the sort with big grub screws in a slot. Do not cut the 6mm cable but strip it, remove the screws from the slot, lay the conductors in the slot, replace the screws. That way you have 1 6mm conductor passing straight through and 1 smaller conductor for the spur. A 45A j.b should be good for up to 2 x 10mm cables.

The whole scheme sounds like a bog-awful mess though. Can't you rip it out and do the job properly? As it's not a standard circuit you should prove full compliance with the IEE regs by calculations. In a kitchen in England and Wales, Part Pee will apply.

Owain

[NikV]

I take it the mcb 5 yards down the passage would not qualify then ??

Ah I was under the misapprenhsion that that the 40A mcb would not protect the smaller cable in the event of a short circuit

I am replacing backboxes as I go - initially set a such angles that the inbuilt adjustment cannot cope

cheers I have no accessible part of the cable but will dig it out and put one of the square 45A jb in line

the electrical quality of the original installation looks fine, all boxes have shielded earths, cables look in good nick (apart from the wonky backboxes) its only the more recent additions - which apparently passed full inspection when the occupants had the consumer unit installed which look dodgy |!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I am tempted to just extend the ring but am temporally challenged at the moment and swmbo wants her kitchen before xmas,

can I derate the mcb to 32A and create a mini-ring at the end of the radial since the 6mm2 is bigger than 2x2.5mm2 - would like to put the fridge on this as its on the non-rcd side 1

As it's not a standard circuit you should

[gort]

Needs to be double pole isolation ie live and nuetral so a MCB does not even qualify.

Dave

[Owain]

Correct, but it also should be within 2m of the appliance.

Owain

[NikV]

oh well 13A double pole fcu it is then - more chasing out :-(