Bonding Back Boxes

Assuming you are talking ring mains and lighting - not cookers etc - 1.5mm is the one. Cut lengths can be expensive - a full reel might be better value.

Wonder if the UK will ever follow Ireland and use T&E with an insulated (full cross-section) earth?

Thanks Dave, Screwfix do 25m of yellow/green 1.5mm2 for £4.99 which is more than I am likely to use so will go with that to make life easier.

Richard

I don't know if you have to use the same size as the circuit wires when using conduit wire? IIRC the reduced cpc size is permitted for twin and earth flat PVC cable but not necessarily for others.

Owain

I thought one of the points of *not* insulating the earth is that if you put a nail or screw through the insulation of the live you are very likely to short to the uninsulated earth. (It is possible, though not so likely, to "nick" the live from the "outside"). Certainly it is harder to sever the live without shorting to earth.

You do not have to use the same size earth as the line conductors although people often do.

Strictly speaking you could 1.5mm for bonding the back box on a cooker circuit as long as it passes the adiabatic check.

Ah - right. I've got a reel of 2.5mm so need to get it used up. ;-)

It does rather sound like a legislator getting involved without actually understanding the engineering. It *might* make the installer's job a little quicker, but at the expense of greater material cost and environmental impact, and for no obvious technical benefit I can see.

A reel? About 4 inches is needed.

Quite. Had it a long time. ;-)

You could probably make do with three, but four gives more wiggle room.

Owai