cable extension

[Nanothermite]

I want to extend a socket cable, basically splice in a new length of cable to
move the socket.
do i use a "30A 3-Terminal Standard Junction Box" to connect the 2 cables?
might seem like an idiot question, but I thought I'd check. thanks.

 

[Taylortwocities]

Not an idiot question, at all.

If you use one of those junction boxes it must remain accessible, so don't think of burying it in plaster or hiding it under the new laminate flooring.

The proper way is to run a whole new length of cable.

 

[ban-all-sheds]

Nano - please note that after you've moved the socket any concealed cables should follow the rules for such, so creating a concealed dog-leg, or bend, for example could well not be OK.

• http://www.voltimum.co.uk/files/gb/attachments/niu/l/attachments/c5-43.pdf
  
  
• http://web.archive.org/web/20061110111450/http://www.niceic.org.uk/downloads/concealedcables.pdf
  
  
• IEE article
  
  
• Current Wiring Regulations requirements for concealed cables.

Also if this socket is in the kitchen the work is notifiable.

 

[Nanothermite]

I wanted confirmation that 30A was the right box, so thanks, it would be fixed on a ceiling joist. concealed between the ceiling and the floorboards, I think that is ok.

is it possibe to bury the cable in a stone wall by going around the stones in a zig zag fasion under the pointing? Yes, I know of course it isn't according to the rules (have read the link provided - thanks). but I really don't want to put some ugly trunking on my beautiful bare stone wall. is there a way to do this without spoiling the wall? I don't think so, but I might be surprised.

I have another option, but would prefer the first option, at least for the location of the socket.

 

[OwainDIYer]

is it possibe to bury the cable in a stone wall by going around the stones in a zig zag fasion under the pointing?

Apart from the safe zones issue, you might not be able to maintain the minimum bending radius for the cable.

Bare copper MICC can look nice against stone (and you can use 1.5mm MICC compared to 2.5mm PVC)

 

[ericmark]

To extend any socket the first step is the measure the loop impedance or prospective short circuit current to ensure once extended the protective device will open within the prescribed time.

Using FCU or a RCD FCU where RCD protection is not already provided will likely result in a spur complying.

Using mineral insulated cable as already stated allows a smaller gauge to be used if one can still keep within the allowed impedance figures. However mineral cable is not the easiest to terminate and using Ali-tube cable may be easier for the novice.

Because mineral and ali-tube can run hotter 2.5mm cable can carry far more power than with twin and earth clipped direct with ali-tube 2.5mm rated at 33A so there is no reduction in current carrying capacity so it is debatable as to if more than one socket could be added.

However one does also need to use JB and sockets also rated at 90 degs C rather than normal 70 degs C so it's not a straight forward answer.

I would consider to get a good hidden cable installation then you need to abandon the idea of DIY and engage some one who as worked with mineral cable to do the work for you. So you are really looking for an old commercial electrician or one use to working on listed buildings. Mineral insulated (Piro as it's normally called) is not normally used in domestic and has in the main been replaced with ali-tube cable it was in the past the normally for fire alarms etc. So it will take some ringing around to find some one experienced in using this type of cable.

 

[ban-all-sheds]

it would be fixed on a ceiling joist. concealed between the ceiling and the floorboards, I think that is ok.

If you use one of those junction boxes it must remain accessible.

is it possibe to bury the cable in a stone wall by going around the stones in a zig zag fasion under the pointing? Yes, I know of course it isn't according to the rules

Then the answer is no, it isn't really possible.

Compliance with the Wiring Regulations is not actually mandatory, but compliance with the Building Regulations is, and it's hard to see how a cable concealed in a random route which nobody could predict, i.e. hidden in places nobody could reasonably expect, which is what the Wiring Regulations forbid for safety reasons, could be said to comply with the Building Regulations requirements for safety.

As Eric said - Pyro is probably the best way to go, given what you've said.

 

[Nanothermite]

it seems to be getting complicated, there's more questions such as how do I connect the 1.5mm pyro to the JB and socket, presumably I strip all the outer plastic sheath exposing all the copper, cut some copper away at the ends to facilitate connecting the internal wires to the socket and the other end to the 30A 90 degree junction box, not so difficult i think, but what about the earth, isn't the earth the outer copper shield or is there an internal earth wire on some pyro cables?

forgot to say, currently there are two cables, one feeding, the other returning as it were, so likely part of a ring, so a pyro would have to a spur from the ring.

I like the idea of copper, so perhaps its easier to use a standard 22mm copper plumbing pipe as ducting for the current cables? is that ok?

 

[ban-all-sheds]

it seems to be getting complicated, there's more questions such as how do I connect the 1.5mm pyro to the JB and socket,

With Pyro glands.

presumably I strip all the outer plastic sheath exposing all the copper,

If it's sheathed.

cut some copper away at the ends to facilitate connecting the internal wires to the socket and the other end to the 30A 90 degree junction box, not so difficult i think,* but what about the earth, isn't the earth the outer copper shield or is there an internal earth wire on some pyro cables?

*Hmmm. Ever done it before? Can you get hold of all of the tools?

//www.diynot.com/wiki/electrics:micc

forgot to say, currently there are two cables, one feeding, the other returning as it were, so likely part of a ring, so a pyro would have to a spur from the ring.

A standard part of the job, however you wire it, would be to check that the socket is on a ring.

I like the idea of copper, so perhaps its easier to use a standard 22mm copper plumbing pipe as ducting for the current cables? is that ok?

That could work - what sort of socket enclosure were you planning?

 

[Nanothermite]

I like the idea of copper, so perhaps its easier to use a standard 22mm copper plumbing pipe as ducting for the current cables? is that ok?

That could work - what sort of socket enclosure were you planning?

basic 3cm plastic back box under standard double socket switches, mounted proud on a piece of oak embedded in the stone wall, cables would exit the top of the back box, the copper pipe (fixed onto the wall with brass fittings) would sit on top of the back box and run into the ceiling.

 

[ban-all-sheds]

Wouldn't a metal box and socket look more in keeping?

I know you can get brass sockets and pattress boxes, and copper sockets, don't know about copper pattresses though.

 

[sparkwright]

Is there a route where you can run the cable horizontally only, to avoid zig-zagging?