"Christian McArdle" wrote in message
.. .
But as 3rd Earl says... don't the brass connecting screws in effect
make an earth connection from the brass faceplate to the metal back
box, to which is connected the supply earth. Same as a flying lead,
really.

Not reliable enough. You want the secure connection to the faceplate and
the
dodgy connection to the backplate. The screws rust and can end up with a
high earth impedence. In the event of an earth fault, this could be high
enough to cause a fire. Unlikely, I know, but not best practice.


Surely the main protection here is to prevent the plate becoming live due to
fault in switch/loose wiring, the earth return needs to have a low enough
impedance to trip breaker/blow fuse (as with all metal cased appliances), as
such I would have thought it essential to have this plate earthed.
Many people do not switch off when loosening screws and pulling forward the
plate when decorating - I can see a loose live wire being pulled out the
terminal to rest on the back of the plate when the plate is released, in
this situation the screws are removed and no earth in place, will give a
shock(maybe severe/fatal) when plate is grabbed - likely fault/severe
consequence = high risk, worth a short length of wire + earth sleeve.

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