I've successfully fitted a dimmer switch.

I've used a small voltage test pen to "direct test" the face plate screws on
other light switches - I've noticed that some of the screws return a direct
test result of between 12 and 36v.

I assume - maybe stupidly - that this is because they are part of an earth
circuit.

Why is it though that some screws do not return a reading?

In article , Gareth
wrote:
I've successfully fitted a dimmer switch.

I've used a small voltage test pen to "direct test" the face plate screws
on other light switches - I've noticed that some of the screws return a
direct test result of between 12 and 36v.

I assume - maybe stupidly - that this is because they are part of an
earth circuit.

Why is it though that some screws do not return a reading?

some boxes are made of plastic, especially those intended for fitting into
plasterboard walls.

--
From KT24

Using a RISC OS computer running v5.16

Is this a proper tester, ie where you need to have a return, or are you in
fact just reading a very high impedence induced voltage using yourself as
the return, in which case maybe its you who is charged and the screws making
the eearth return.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"charles" wrote in message
...
In article , Gareth
wrote:
I've successfully fitted a dimmer switch.

I've used a small voltage test pen to "direct test" the face plate screws
on other light switches - I've noticed that some of the screws return a
direct test result of between 12 and 36v.

I assume - maybe stupidly - that this is because they are part of an
earth circuit.

Why is it though that some screws do not return a reading?

some boxes are made of plastic, especially those intended for fitting into
plasterboard walls.

--
From KT24

Using a RISC OS computer running v5.16

In article , charles
scribeth thus
In article , Gareth
wrote:
I've successfully fitted a dimmer switch.

I've used a small voltage test pen to "direct test" the face plate screws
on other light switches - I've noticed that some of the screws return a
direct test result of between 12 and 36v.

I assume - maybe stupidly - that this is because they are part of an
earth circuit.

Why is it though that some screws do not return a reading?

some boxes are made of plastic, especially those intended for fitting into
plasterboard walls.


Sometimes the "earth" on lighting circuits isn't connected too well and
the faceplate screws are "floating" above Earth potential thats to say
there're picking up a small voltage via Capactive and inductive effects
via leakage in the wiring.

You'll find that this will disappear if they are correctly earthed..


--
Tony Sayer

Are you sure thee ones which dont return a reading ar actually connected to
earth though.
Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"Gareth" wrote in message
...
I've successfully fitted a dimmer switch.

I've used a small voltage test pen to "direct test" the face plate screws
on other light switches - I've noticed that some of the screws return a
direct test result of between 12 and 36v.

I assume - maybe stupidly - that this is because they are part of an earth
circuit.

Why is it though that some screws do not return a reading?

In article ,
Gareth wrote:
I've successfully fitted a dimmer switch.

I've used a small voltage test pen to "direct test" the face plate
screws on other light switches - I've noticed that some of the screws
return a direct test result of between 12 and 36v.

I assume - maybe stupidly - that this is because they are part of an
earth circuit.

Why is it though that some screws do not return a reading?

Was there an earth wire inside the switch backing box and was it connected?
Older wiring may not have any earth on the lighting circuits. So you must
only use plastic light switches and dimmers with that. And correctly, the
screws should only be plastic - or if metal have a plastic cover.

--
*I wish the buck stopped here. I could use a few.

Dave Plowman London SW
To e-mail, change noise into sound.