voltage at ceiling fixture with switch off
 

I had an old round flourescent ceiling fixture in the kitchen that gave
out (house was built in late 1960s). The box is fed by two sheathed
electrical cables, one cable with white and black, the other cable white,
black and red. Both the hallway switch and kitchen switch operate the
fixture (both switches are the "on/off" kind, not the round dial thing).

I put in an incandescent (single 60W) fixture and used the red wire for
hot since that's what the flourescent was hooked to. After hooking up the
neutral and ground I turned the power back on and with a volt-ohm meter
see there's 48V at the socket with the switches in one position and about
120V when they're in another.

My problem is the 48V when it's supposed to be off. I've toggled both
switches in every possible combination and there's never ~0V at the socket
- it's never less than 48V. Can someone tell me wtf is going on with this
thing? Getting to it from the attic is a major PITA and I can't see
anything through the electrical box - is there something else up there,
maybe because it was hooked to a flourescent light or something? What
purpose could there possibly be to not have 0V when the switches are off?
I don't want to put a light bulb in it until I know why off isn't 0V.

Mike
--

Mike Ballard wrote:
I had an old round flourescent ceiling fixture in the kitchen that
gave out (house was built in late 1960s). The box is fed by two
sheathed electrical cables, one cable with white and black, the other
cable white, black and red. Both the hallway switch and kitchen
switch operate the fixture (both switches are the "on/off" kind, not
the round dial thing).

I put in an incandescent (single 60W) fixture and used the red wire
for hot since that's what the flourescent was hooked to. After
hooking up the neutral and ground I turned the power back on and with
a volt-ohm meter see there's 48V at the socket with the switches in
one position and about 120V when they're in another.

My problem is the 48V when it's supposed to be off. I've toggled both
switches in every possible combination and there's never ~0V at the
socket - it's never less than 48V. Can someone tell me wtf is going
on with this thing? Getting to it from the attic is a major PITA and
I can't see anything through the electrical box - is there something
else up there, maybe because it was hooked to a flourescent light or
something? What purpose could there possibly be to not have 0V when
the switches are off? I don't want to put a light bulb in it until I
know why off isn't 0V.

Mike

Get an old analog meter and I'll bet you will get 0 volts. Those new
digital ones are so sensitive that they pick up stray voltage that is very
very weak current. It happens when the wires you are testing happen to have
run close to some other wires that hare being used. It may change as other
switches are turned on or off.

Try putting a 120 V lamp across it. If I am right it will not light at
all and the meter will read 0.


--
Joseph Meehan

Dia duit

Mike Ballard wrote:
I had an old round flourescent ceiling fixture in the kitchen that
gave out (house was built in late 1960s). The box is fed by two
sheathed electrical cables, one cable with white and black, the other
cable white, black and red. Both the hallway switch and kitchen
switch operate the fixture (both switches are the "on/off" kind, not
the round dial thing).

I put in an incandescent (single 60W) fixture and used the red wire
for hot since that's what the flourescent was hooked to. After
hooking up the neutral and ground I turned the power back on and with
a volt-ohm meter see there's 48V at the socket with the switches in
one position and about 120V when they're in another.

My problem is the 48V when it's supposed to be off. I've toggled both
switches in every possible combination and there's never ~0V at the
socket - it's never less than 48V. Can someone tell me wtf is going
on with this thing? Getting to it from the attic is a major PITA and
I can't see anything through the electrical box - is there something
else up there, maybe because it was hooked to a flourescent light or
something? What purpose could there possibly be to not have 0V when
the switches are off? I don't want to put a light bulb in it until I
know why off isn't 0V.

It's not a problem. Ignore the 48v. It's not real. The presence of induced
voltage is normal. Forget about it.

Mike Ballard wrote:

I had an old round flourescent ceiling fixture in the kitchen that gave
out (house was built in late 1960s). The box is fed by two sheathed
electrical cables, one cable with white and black, the other cable white,
black and red. Both the hallway switch and kitchen switch operate the
fixture (both switches are the "on/off" kind, not the round dial thing).

I put in an incandescent (single 60W) fixture and used the red wire for
hot since that's what the flourescent was hooked to. After hooking up the
neutral and ground I turned the power back on and with a volt-ohm meter
see there's 48V at the socket with the switches in one position and about
120V when they're in another.

My problem is the 48V when it's supposed to be off. I've toggled both
switches in every possible combination and there's never ~0V at the socket
- it's never less than 48V. Can someone tell me wtf is going on with this
thing? Getting to it from the attic is a major PITA and I can't see
anything through the electrical box - is there something else up there,
maybe because it was hooked to a flourescent light or something? What
purpose could there possibly be to not have 0V when the switches are off?
I don't want to put a light bulb in it until I know why off isn't 0V.

Mike
Hi,
If you are using digital meter, disregard reading. Due to high input
impedance it'll pick anything as stray induced voltage. One reason I
still keep and depend on my old Simpson 260 analog meter. Install a bulb
and measure the voltage, there'll be nothing actually when in off state.
Tony