Is it safe to have a solid and a stranded wire go into an earth terminal in a metal dimmer switch?

[PotatoSoup]

Hi there, thank you for reading this
I'm replacing a like for like dimmer switch at my brother's house. They have bought a 1-core 1.5mm2 stranded cable for me to use to connect the back box to the new dimmer switch.
Please could someone tell me, is it ok to use a length of stranded Green/Yellow 1-Core 1.5mm² Conduit Cable to connect a metal back box and metal dimmer switch? If it is ok, can this stranded wire go into the same earth terminal as the solid 1.5mm2 wire going into the switch's earth terminal from the t&e cable? I'd appreciate any help - thank you!

 

[JohnW2]

Please could someone tell me, is it ok to use a length of stranded Green/Yellow 1-Core 1.5mm² Conduit Cable to connect a metal back box and metal dimmer switch?

Yes.

If it is ok, can this stranded wire go into the same earth terminal as the solid 1.5mm2 wire going into the switch's earth terminal from the t&e cable?

Again, yes. However, if the switch has two earth terminals, you could also put one wire into each of you would prefer.

Kind Regards, John

 

[bernardgreen]

I would say that it depends on the way the terminal grips the strands and whether the strands can avoid the clamping screw,

The green is the solid core and the reds are the strands which may not be under any pressure from the screw.

Crimping the strands with a bootlace crimp will reduce the risk of poor connection,

Worst case is that one strand is tight under the screw and continuity tests show a connection, However when there is a fault causing high currents in the earth this single strand melts and as a result there is no effective Earth connection between the terminal and the stranded wire.

 

[PotatoSoup]

Thank you so much, I really appreciate your responses and the speed of them too. I will double check the strands haven't separated. Thank you, Both!!

 

[JohnW2]

I would say that it depends on the way the terminal grips the strands and whether the strands can avoid the clamping screw,

The green is the solid core and the reds are the strands which may not be under any pressure from the screw.

I can't disagree with that, but I don't think that the 'risks' to which you refer are appreciably greater when there is also a solid conductor in the terminal than when the stranded one is on its own in a terminal.

What we do to minimise that risk is obviously to ensure that the strands are firmly twisted together before inserting it into a terminal, and being careful to ensure that that 'twisting' is not disrupted (i.e. some strands 'coming loose') when it is inserted into the terminal.

Crimping the strands with a bootlace crimp will reduce the risk of poor connection,

Yes, probably, although I very much doubt that (m)any electricians would actually do that when connecting to an electrical accessory. It does, of course, although introduce another possible 'mode of failure' (the conductor coming loose' within the crimp.

Kind Regards, John