Plastic to brass light switch: extra earth required?
 

I recently replaced a plastic light switch with a brass victorian type.
Coming from the ceiling were 2 x red wires and an earth, which
connected securely to the metal mounting box.

Question: There is an earth terminal on the back of the brass
faceplate. Do I need to connect this to the earth on the back box?

Thanks,
Bruce

Plastic to brass light switch: extra earth required?
 

Plastic to brass light switch: extra earth required?
 

The3rd Earl Of Derby wrote:

No, as the securing screws to back box will suffice.

Unless the back box is plastic, in which case, connect the earth to the
terminal on the switch plate instead of parking it in the terminal on
the backbox.

Plastic to brass light switch: extra earth required?
 

"The3rd Earl Of Derby" wrote in message
. uk...

No, as the securing screws to back box will suffice.

Tsssss!

If the back box has at least one fixed (non-sliding) lug, then it's
considered that the fixing screws are sufficient to earth the box *from* the
accessory.

I wouldn't dream of doing it the other way around with a brass accessory.
IMO, the OP should earth the switch properly.

Will

Plastic to brass light switch: extra earth required?
 

Plastic to brass light switch: extra earth required?
 

I recently replaced a plastic light switch with a brass victorian type.
Coming from the ceiling were 2 x red wires and an earth, which
connected securely to the metal mounting box.

Question: There is an earth terminal on the back of the brass
faceplate. Do I need to connect this to the earth on the back box?

You need to connect the cable earth to the back of the brass faceplate. You
can also run a flying lead from the faceplate earth to the backbox. This
isn't usually required, but is often taken as a sign of a conscientous
installer.

Don't do it the other way, though. The circuit earth should go directly to
the accessory, not the backbox. It was only run this way before because the
existing white plastic switch won't have had an earth terminal.

Christian.

Plastic to brass light switch: extra earth required?
 

Thanks.
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.

I always turn the power supply off before I unscrew any switch face
plates.

Thanks,
Bruce

Plastic to brass light switch: extra earth required?
 

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.

I always turn the power supply off before I unscrew any switch face
plates.

I don't. Nor do many others. I might want the lights on when decorating
behind the faceplate.

Christian.

Plastic to brass light switch: extra earth required?
 

"Christian McArdle" wrote in message
.. .
I recently replaced a plastic light switch with a brass victorian type.
Coming from the ceiling were 2 x red wires and an earth, which
connected securely to the metal mounting box.

Question: There is an earth terminal on the back of the brass
faceplate. Do I need to connect this to the earth on the back box?

You need to connect the cable earth to the back of the brass faceplate.
You
can also run a flying lead from the faceplate earth to the backbox. This
isn't usually required, but is often taken as a sign of a conscientous
installer.

Don't do it the other way, though. The circuit earth should go directly to
the accessory, not the backbox. It was only run this way before because
the
existing white plastic switch won't have had an earth terminal.

Christian.



Curiosity question.

What do you do when the earth is too short? ie someone has cut it just long
enough to reach the earth terminal of the backbox but it will not reach the
earth terminal on the metal faceplate.

A flylead must still be used from the backbox terminal to the metal
faceplate but would it pass an inspection?

IMHO it would even though it is not the preferred method of installation

Adam

Plastic to brass light switch: extra earth required?
 

"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.

--
(º·.¸(¨*·.¸ ¸.·*¨)¸.·º)
.·°·. NIK .·°·.
(¸.·º(¸.·¨* *¨·.¸)º·.¸)

Plastic to brass light switch: extra earth required?
 

wrote:

I always turn the power supply off before I unscrew any switch face
plates.

By opening the (single pole) MCB perhaps? If so remember that you ought
to treat the neutral as a live conductor as well - hence you still want
the back box earthed even if the screws are removed.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Plastic to brass light switch: extra earth required?
 

A flylead must still be used from the backbox terminal to the metal
faceplate but would it pass an inspection?

Personally I would say it is OK, provided there is a flying lead and no
reliance on the screws. I'm not an inspector, though!

Christian.

Plastic to brass light switch: extra earth required?
 

Plastic to brass light switch: extra earth required?
 

On Tue, 04 Apr 2006 17:06:57 +0000, ARWadsworth wrote:


"Christian McArdle" wrote in message
.. .
I recently replaced a plastic light switch with a brass victorian type.
Coming from the ceiling were 2 x red wires and an earth, which
connected securely to the metal mounting box.

Question: There is an earth terminal on the back of the brass
faceplate. Do I need to connect this to the earth on the back box?

You need to connect the cable earth to the back of the brass faceplate.
You
can also run a flying lead from the faceplate earth to the backbox. This
isn't usually required, but is often taken as a sign of a conscientous
installer.

Don't do it the other way, though. The circuit earth should go directly to
the accessory, not the backbox. It was only run this way before because
the
existing white plastic switch won't have had an earth terminal.

Christian.



Curiosity question.

What do you do when the earth is too short? ie someone has cut it just long
enough to reach the earth terminal of the backbox but it will not reach the
earth terminal on the metal faceplate.

Crimp on an extension. and sleeve the crimp G&Y.





--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

Plastic to brass light switch: extra earth required?
 

The recommendation is to take the protective conductor to the accessory
and loop that to the back box. This is because of the poor quality of
the terminal in most metal "plaster" boxes. The brass terminals in old
MK boxes were OK but most of the others are horrible , fill up with
plaster and corrode easily.
If you have enough length you can loop it without a join.
--
Neil J. Harris