Twin and earth or flex?

[Commander Kinsey]

Why do we use twin and earth when flex is only 10% more expensive and a lot easier to connect and route and won't snap if it's bent too often?

[Brian Gaff]

I thought if bare earth, somebody told me it made sure that any faults that rubbed on the wire would be earthed, but I never really bought into that one myself. If you went down that route then we would get a better result using coaxial cables. Brian

[ARW]

I do believe the RoI use a sleeved earth on their T&E.

[Commander Kinsey]

Yes, like the ones underground powering your house, a JCB slices through neutral/earth before it hits live, so the short is within the wire itself.

The bare earth twin and earth cables don't protect as you say, because if the fault rubs the side of the flat cable that has live, it will hit that before earth.

[alan_m]

Much too easy to mis-connect a multi-stranded wire than a single copper wire? Much easier to have one strand of a multi-strand wire not in a screw connector and therefore more potential for shorting to other connections or another floating strands. Poor stripping of multi-stranded wire and you lose some of the strands and hence current carrying capacity.

You could minimise some of the above by fitting ferrules - but at extra cost and time.

[Commander Kinsey]

Any sensible electrician uses an auto stripper which grips perfectly and never damages strands. Then you just twist them and they become one, but bendable.

[Commander Kinsey]

Forgot to add, if you put a single copper wire into a grubscrew and have lots of space left over, it can miss the screw and slip off later. Strands spread out under the screw and always get a good grip. I often find sockets done with single wires where they've popped out over time.

[Dean Hoffman]

Inertia? Were receptacles and such originally designed just to have a wire bent around the screw? Stranded wire would've needed a spade end then?

[Commander Kinsey]

I remember old UK mains plugs (I still use a couple) where the is wrapped round a sticking up screw thread, then a nut is tightened on top. They actually work better with flex, as you just twist the strands, then the result is easily curved into shape. I can't think of any receptacle that would work better with solid wire.

[Commander Kinsey]

And so they should. Pretty stupid to have an earth floating about inside a receptacle. Most decent electricians put an earth sleeve over it.