DIY Extension Cable

12-01-2022 12:22PM #1

I'm looking to update my extension cable.

Currently it is terminated in something similar to this. https://www.screwfix.ie/p/masterplug-13a-2-gang-unfused-rewireable-socket-black/76329

However it looks tacky and I'd love to replace it with a proper plug socket and back box.

The problem is the rewriteable socket has one terminated point for each Live, Earth and Neutral. All the two gang sockets have two separate terminating points for earth.

I'm obviously a bit wary of doing something wrong so would appreciate any advice other than 'get an electrician' as I'm just interested in how it all works.

10-10-20 · 12-01-2022 01:32PM

So you want to go from a "robust, heavy duty, rewireable socket" to a metal back-box and double socket? Is this for taste or is there a practical reason for it?

I have found some of the common metal back-boxes are less robust than they look, so I'd be careful to pick one which is kitted together with a backbox and plug socket so that they interlock and are robust (if such exists) or come from the same manufacturer.

Anyhow the earthing is done in a way where the plug socket pins are earthed solidly to the metal backbox and the front-plate of the socket so that they are all "equipotentially bonded". Normally this is achieved by running a sheathed earth wire of the same cross-sectional area as the incoming lead (such as 1.5mm^2 or 2.5mm^2) between the back of the socket and the back-box. It's documented here: https://www.voltimum.co.uk/articles/earthing-metal-back-boxes

Can I just also caution that while you are at this you need to check the existing cable for damage and also review the condition of the plug on the other end of the cable to the new box and also review the fuse installed so that it sufficiently protects the cable. You also need to ensure very good strain-relief on the backbox, so you will need to fit a gland to protect the cable insulator.

https://www.screwfix.ie/p/tower-nylon-male-comp-gland-20mm-2-pack/80851

Finally, if the extension cord is being used externally, consider fitting an RCD in place of the existing plug-socket for additional protection.

https://www.screwfix.ie/p/masterplug-13a-unfused-plug-in-active-rcd-plug/44855#product_additional_details_container

Wheety · 12-01-2022 03:19PM

Any pictures of the current extension cable?

What do you want to do with it? Are you plugging the other end into a socket and then want sockets fixed to a wall on this end too? Is it going outside the house?

12-01-2022 05:22PM

The current setup is this plug, connected to this wire, connected to this socket.

So you want to go from a "robust, heavy duty, rewireable socket" to a metal back-box and double socket? Is this for taste or is there a practical reason for it?

I would like to have a plastic back-box and double socket. Currently the socket is just on the floor as it cannot be attached to the wall. This means it's getting knocked and I'm worried it will be damaged. It also doesn't look well.

What do you want to do with it? Are you plugging the other end into a socket and then want sockets fixed to a wall on this end too? Is it going outside the house?

Ideally I will be screwing the sockets into the wall - Was thinking of combing this socket with this backbox

12-01-2022 09:18PM

Could I just use this https://www.screwfix.ie/p/mk-logic-plus-13a-2-gang-dp-switched-plug-socket-white/15747 since it looks like there is just one earth terminating point.

So this and a this plastic back-box would work?

Spook_ie · 12-01-2022 09:29PM

Would you not just use one of these

https://www.screwfix.ie/p/masterplug-13a-2-gang-unfused-rewireable-socket-black/76329

and mount it on the wall?

Also in white

https://www.screwfix.ie/p/masterplug-13a-2-gang-fused-rewireable-socket-white/97659

12-01-2022 09:31PM

It doesn't come with an easy way to mount it to a wall, and the I'd much rather the full socket as it looks much better.

If it would work and is safe.

Spook_ie · 12-01-2022 09:36PM

https://www.boards.ie/discussion/comment/118464052#Comment_118464052

Well i wouldn't be using any of the plastic boxes or sockets if it's ever going to be used as a "normal" extension lead, i reckon just too brittle for the knocks and bangs an extension lead gets.

12-01-2022 09:53PM

https://www.boards.ie/discussion/comment/118464085#Comment_118464085

No it will be wall mounted and always will be. The reason I'm leaning towards the plastic backbox and socket is for looks but also the fact it will be far more secure and less likely to get damaged.

Wheety · 12-01-2022 11:53PM

You don't have to use the 2 earth terminals, you can use either. They're generally joined anyway.

What's the setup here? Is it going from one part of the house to another? Is it going to an outbuilding?

I'm not sure if 1.5mm cable is rated for a double socket. You'd be better off spurring off from the current socket (presuming it's not already a spur) with 2.5mm cable and using a socket like you've linked.

13-01-2022 12:07AM

What's the setup here? Is it going from one part of the house to another? Is it going to an outbuilding?

Just going from one part of a room to another. Not to an outbuilding or anything.

Wheety · 13-01-2022 12:51AM

https://www.boards.ie/discussion/comment/118465017#Comment_118465017

Can you run cable under floorboards? I think the a more permanent solution, spurring off from a socket would be the best.

MuttonDagger · 13-01-2022 08:59AM

I need to see this

pics please

13-01-2022 02:09PM

https://www.boards.ie/discussion/comment/118465223#Comment_118465223

Not really no. Currently it is run under cabinets behind the kickboard, then out of a hole on the side of the cabinet. It's extremely neat and all the cable plugs are hidden away. Which is why I'd love to replace the double socket with something that looks better and is more secure.

It sounds like my plan will work though?

DIY Extension Cable

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