Mains wiring

[BartC]

Was replacing a couple of 13A sockets today, and noticed some wire cores were silver-coloured all the way through, instead of copper.

What is this material likely to be, aluminium?

Also noticed these wires were mixed in with normal copper wires in the same terminals; would this be a problem?

(Some time ago, there was sparking from inside my fusebox, which caused damage to the wires and terminal. I moved them to a neighbouring unused terminal until I get round to getting the whole thing replaced. But I read somewhere that aluminium cable, if it is that, does not stay tight in a screw-terminal. Was that likely to be the problem? Although I can't remember now if those wires were copper or not.)

(If whoever wired up my 40-year-old house was trying to save money, then they went a bit too far because there was no slack whatsoever in the cabling behind the sockets; you could only pull the front out about half an inch, and the new sockets had terminals in a different layout..)

[Tabby]

yes

yes

it might have been

aluminium wire with the proper aluminium compatible terminations is a risk factor for fire, but its not too bad. Ali wire in connectors intended for copper is a bigger fire risk. You might find your house insurance invalid if you dont declare its presence.

The ideal solution is a rewire of any ali sections. Most owners leave the ali in place though. If you did the latter, and you've got a mix of copper and ali, then uising the ali circuits for only low power devices would at least reduce the risk.

NT

[Tabby]

If you ever get a good clear pic of it, the wiki would benefit from it.

NT

[Andrew Mawson]

[Neil Williams]

You might find that it's actually tinned copper. This isn't silver- coloured all the way through, but only on the outside - but it isn't necessarily very visible on smaller gauges of wire. There seems to be some of this in my house - I was originally concerned it was ally but was pleased to find that it wasn't.

Cut the end cleanly off one and see if you can see the copper core - if so it isn't ally.

seems to refer.

Neil

[Neil Williams]

Same with mine. It's making replacing the mucky white plastic sockets/ switches with nice chromed steel ones take rather more time and patience than I thought.

Neil

[Huge]

The overhead feed to my house is aluminium, and it's only a couple of years old. It's a pair of insulated of Al cables in a "figure of eight" configuration.

[dennis]

I can't rewire sockets with wires that short due to having large fingers, the solution is to crimp some longer bits on. Its probably the solution to terminating ali cables too.

[Nightjar]

National Grid overhead power lines have used aluminium for a long time. Even though it needs a larger cross-sectional area, it is lighter than copper with the equivalent capacity.

Colin Bignell

[Tabby]

sockets today, and noticed some wire

There's nothing wrong with using ali for large conductor sizes, using the right type of connectors, by businesses that can be relied on to do it correctly. The problems occur with smaller sizes used in homes. Its very susceptible to fracture, surface oxidation, and creep, which results in high resistance junctions, the prime cause of fire.

NT