Extending Lighting Cable

[stuart_arthur]

I've recently relocated my landing light but I had to extend the cables. In total 3 lives, 3 neutrals and 3 earth's from three 3 core cables.

I'm just hoping someone could let me know if what I've done is acceptable or if I should have done this in another way?

I joined each cable by twisting the 2.5 mm wire together. Over and under and used heat shrink sleeves over each individual wire join, each live, each neutral etc. I then used larger heat shrink sleeve for each 3 core cable so that the grey sheath that in cases the 3 wires is Un breached.

Ultimately is this safe or should I redo it?

Thanks

 

[stillp]

No, twisting is not sufficient. The surface of the copper will oxidise and the joint will go high resistance. Either use a junction box (maintenance-free if it will be inaccessible), or crimps, or solder.

 

[stuart_arthur]

Thank you for your reply. By high resistance I guess it will get to a point where the light stops working? Is that right?

Is their any risk of fire or anything like that?

I will look at the maintenance free boxes.

 

[stillp]

It could stop working correctly, or depending on the lamp it could just overheat, which would be a fire risk. A small risk, but unnecessary.

 

[stuart_arthur]

Okay thanks. Would a 20 amp box be sufficient?

 

[stillp]

For a landing light? Plenty, but it won't do any harm.

 

[stuart_arthur]

Okay thanks, I only ask as I can only find 20 amp maintenance free boxes but my lighting circuit is on a B6 mcb. Am I right in thinking anything lower than 6 could over heat but anything over is fine as the mcb would trip before anything happened to that junction box?

 

[stillp]

Yes!

 

[DaveHerns]

Where does the 2.5mm cable come into the picture ? 1.0 mm is adequate for a lighting circuit

 

[stuart_arthur]

That was the cable already up there. I thought I'd join like to like.

 

[DaveHerns]

I don't think a 20 amp junction box will take 3 or 4 2.5mm cables. I wonder why your lighting circuit was done in 2.5mm cable?

 

[stuart_arthur]

I have three T&E cables I have extend. I will now change my joins to an in line junction box. I will use a a junction box for each cable, so three in total.

 

[ericmark]

My old books describe how to join wire using western role which was in essence twisting them together. It was used for telephone cables, personally I would say a little wetting with solder is requires to prevent any oxidation over time causing a bad connection. Using a maintenance free is much easier I would only join cables using shrink or epoxy resin where no other method could be used. Solder today is a problem. It's not the solder it's the flux. With old proper lead solder resin core flux was enough and it did not harm the joint being left there. Today with lead free the flux is really bad, you need extractors to stop you breathing in the fumes from the flux and solvents to remove the flux to stop it damaging the cable.

 

[ban-all-sheds]

http://web.archive.org/web/20100215151002/http://www.markhellerelectric.com/solder.pdf

 

[sparkwright]

How do you know it's 2.5mm2 cable? Very odd for domestic lighting.