Blown ceramic fuse with light switch help

Been doing a bit of decorating in the flat and had the bedroom light switch loosened to paint round it.

Went to tighten it back it and there was a flash and allt he lights went out.

I have to get my old ceramic fuse box replaced in the near future but for now will get some new wire for the fuse tomorrow.

My question is......

I took the light switch off and it's got a metal casing in the wall.

There are red wires going into the switch for on and off and green wires all tied together and in nothing. Should these be attached to the metal casing? Or touching it?

And is this why it fused?

And should I replace it with a plastic one?

Will try and post a pic tomorrow... it's too dark and I can't see.

EDIT: Just looked at another plug with a metal casing in the hallwayand there is a point for the grren wires to be screwed into on the casing.

The one on the bedroom doesn't have this... I guess they must have come away from the casing when I loosened the switch for painting....

John

Usually there is an earth terminal on metal back boxes to connect the earth wires.

When you say the green earth wires were 'tied' together, do you mean twisted together not connected to anything?

If the terminals on the switch touched this it certainly would blow the fuse/mcb.

You need to need to connect the wires to the box earth terminal, if there is one.

If the switch box is metal, with nylon fixings for the switchplate screws, there probably isn't an earth terminal provided.

Ideally, you should still earth the box.
One way would be to crimp red lugs onto each earth wire, and connect them via a screw through the box.

Thanks for your reply.

There was no earth terminal on the metal box so I replaced it out for a new one.

All working fine.

Thanks for your help!

John