Extending Mains Cables

Martynt74 · 19 May 2014 at 14:15

I'm planning to change the light fitting for the ceiling light in my daughters room.

I've bought a standard plastic rose and came to take the old light off thinking it would be a nice simple process. However it seems the existing mains wires are really short to the point they won't fit.

Whats the best way to extend this? And where can i buy mains cable in short lengths?

I suppose the main question is this something that i can safely do myself?

There is also no existing earth cable. Am i also correct in thinking that with it being a plastic rose an earth connection isn't required?

Beer_MonsterUK · 19 May 2014 at 15:48

Buy some 5amp connector blocks and a few metres of 1.5mm Twin & Earth, easily available at B & Q to extend the cable. I know it sounds obvious, but pull the fuse/isolate the MCB in the fuse box first. A lot of people just turn the switch off thinking it is dead and get a decent belt off the neutral backfeed. Ouch!

Sounds like it's a very old electrical installation if CPC's (earths) aren't installed, you are very limited to plastic/Class 2 equipment. If there's a fault with the metallic light fitting/switches it will just make the metallic parts live instead of activating the protective device within the required time.

Lopéz · 19 May 2014 at 19:46

You can crimp extra lengths on, I've also used Wago connectors in the past, better than connector blocks in my opinion and very easy and quick to work with.

Adam · 20 May 2014 at 08:09

Wago connectors are fantastic, used them for the first time to do something similar to what the OP needs and they really made things a lot simpler.

john_s · 20 May 2014 at 08:45

Another vote for Wago connectors from me too. Easier, less fiddly, and more secure than choccy block connectors.

bmh.01 · 20 May 2014 at 09:51

Beer_MonsterUK said:
Buy some 5amp connector blocks and a few metres of 1.5mm Twin & Earth, easily available at B & Q to extend the cable. I know it sounds obvious, but pull the fuse/isolate the MCB in the fuse box first. A lot of people just turn the switch off thinking it is dead and get a decent belt off the neutral backfeed. Ouch!

Sounds like it's a very old electrical installation if CPC's (earths) aren't installed, you are very limited to plastic/Class 2 equipment. If there's a fault with the metallic light fitting/switches it will just make the metallic parts live instead of activating the protective device within the required time.

Neutral back feed? Wtf are you talking about, they'll get a belt off the live loop not the neutral if they don't isolate the circuit. You can hold on to the neutral all day long unless there is a fault somewhere as it should be (near enough) at 0v potential. The neutral doesn't even get broken when you pull fuse/isolate mcb.

Lopéz · 20 May 2014 at 13:23

Adam said:
Wago connectors are fantastic, used them for the first time to do something similar to what the OP needs and they really made things a lot simpler.

I've got loop at switch in my house so there is sometimes a lot going on in the switch box, especially with earths. I use a Wago in the switch box to grip the earths together and then just run one earth up to the switch plate. It's a lot less hassle than trying to squeeze three or four earth wires in to a switch plate terminal.

Beer_MonsterUK · 20 May 2014 at 17:19

bmh.01 said:
Neutral back feed? Wtf are you talking about, they'll get a belt off the live loop not the neutral if they don't isolate the circuit. You can hold on to the neutral all day long unless there is a fault somewhere as it should be (near enough) at 0v potential. The neutral doesn't even get broken when you pull fuse/isolate mcb.

Do i really have to draw out a simple lighting circuit for you?

If he doesn't pull the fuse and relies on the switch for isolation then splits the neutral he will get a potentially deadly electrical shock backfed from another light on the circuit. It's common practice for people not familiar with electrics to just switch the light off and change fittings. I've heard it countless times.

The neutral WILL get broken when he splits the loop in/out neutral.

Depending on how the lighting circuit has been wired, a loop live is not forced to be in the lighting rose and could be in the switch.

Millwall.FC · 20 May 2014 at 17:46

bmh.01 said:
Neutral back feed? Wtf are you talking about, they'll get a belt off the live loop not the neutral if they don't isolate the circuit. You can hold on to the neutral all day long unless there is a fault somewhere as it should be (near enough) at 0v potential. The neutral doesn't even get broken when you pull fuse/isolate mcb.

You have really made a ass out of yourself.
What he meant is an open circuit, any one with any electrical savvy could see what he was on about. You break a neutral in a live circuit and it will be live up until the break. basic stuff really.

Traffic_Warden · 20 May 2014 at 18:23

bmh.01 said:
Neutral back feed? Wtf are you talking about, they'll get a belt off the live loop not the neutral if they don't isolate the circuit. You can hold on to the neutral all day long unless there is a fault somewhere as it should be (near enough) at 0v potential. The neutral doesn't even get broken when you pull fuse/isolate mcb.

OK you hold onto this neutral, I'll switch all the other lights on within this circuit, and switch the switch for this light off. See how long you hold on for.

Yeeeeeeehaaaaaaaaaaa Cowboy

Beer_MonsterUK · 20 May 2014 at 19:23

Neutrals are frikking deadly, you assume they "should" be a 0 volt potential and they can bite.

Nedved11 · 20 May 2014 at 22:12

Also good thing about wago connectors is that they can be classified as maintenance free so can be kept under floors or celing voids. Bear in mind they will need to be enclosed in some sort of enclosure such as a wago box or a terminal box which has cable snag protection.

Martynt74 · 22 May 2014 at 09:32

Cheers guys, those Wago things look great. I believe that the current light seems to use something similar built into the wiring.

I looked at Screwfix and they seem to sell them in packs of 100. Is there a place to buy just a couple?

Lopéz · 22 May 2014 at 11:10

Ebay, I think you can get bags of 5 or 10.

lewism · 24 May 2014 at 16:22

bmh.01 said:
Neutral back feed? Wtf are you talking about, they'll get a belt off the live loop not the neutral if they don't isolate the circuit. You can hold on to the neutral all day long unless there is a fault somewhere as it should be (near enough) at 0v potential. The neutral doesn't even get broken when you pull fuse/isolate mcb.

Hahaha. If you're an electrician this is very scary.

Jez · 24 May 2014 at 16:54

Lopéz said:
You can crimp extra lengths on, I've also used Wago connectors in the past, better than connector blocks in my opinion and very easy and quick to work with.

Another bonus with wago is that they can within part P be buried in inaccessible places as they are deemed maintenance free (no screw terminals). Ideal if you cant be bothered with old school crimping which used to be the only alternative for burying in inaccessible places