Broken Switch

[sgoldswo]

I purchased a new 2gang switch from B&Q (branded volex) in stainless steel to replace the switches used to control my bathroom lighting. I fitted it to replace an old paint covered MK switch, matching wires to equivalent terminals. All I added was a loop of wire to connect the earth terminal in the back box to the earth terminal in the front plate of the switch.

Whatever I did the new switch would cause the consumer unit to trip. Not sure why. Reinstalled old switch and the lighting worked and the consumer unit is fine. Assumed it was the earth so tried again with the earth wire to front plate disconnected and again the consumer unit tripped. Swapped in the old switch again.

My diagnosis is a faulty new switch - sound about right?

 

[JohnW2]

What tripped - an MCB or an RCD (the latter identified by having a test button, and probably by "RCD" written on it!)?

Kind Regards, John

 

[RF Lighting]

I'll bet you £1000 it's not a faulty switch.

Please post photos of the wiring at your switch position.

 

[ban-all-sheds]

All I added was a loop of wire to connect the earth terminal in the back box to the earth terminal in the front plate of the switch.

Why not just move the earth conductor from the box to the switch?

 

[JohnW2]

All I added was a loop of wire to connect the earth terminal in the back box to the earth terminal in the front plate of the switch.

Why not just move the earth conductor from the box to the switch?

... perhaps because that would leave the back box unearthed, other than via faceplate screws?

Kind Regards, John

 

[ban-all-sheds]

But it's not an exposed conductive part when the switch is in place.

 

[JohnW2]

But it's not an exposed conductive part when the switch is in place.

No, but the hazard is probably at its greatest when the screws are removed and the switch pulled forward, maybe causing a live conductor to come out of the switch terminal and come into contact with the backbox.

Of course, one shouldn't be doing that on a 'live' switch, but I don't think that's the point. Are you saying that you don't believe in earthing metal back boxes?

Kind Regards, John

 

[ban-all-sheds]

I'm saying I'd rather have the switch plate earthed directly.

 

[JohnW2]

I'm saying I'd rather have the switch plate earthed directly.

So would I (assuming it would reach comfortably), but I would then run an earth conductor from the switch plate to the back box, if it were metal.

Kind Regards, John

 

[sgoldswo]

Thank you and I was going to post a photo on this one which had me stumped.

I've since worked out what I did wrong, I'm such a moron, its all down to the way the original switch terminals are arranged on the rear of the existing switch (ie there aren't two separate switch units as there are on most modern 2 gang switches, just 6 terminals on a single unit, which had led me to switch the live wires to the "opposite" switch on my replacement). Really dumb...

 

[Taylortwocities]

I'll bet you £1000 it's not a faulty switch.

@sgoldswo Did you take the bet?