A friend asked me to help her repair her bathroom light switch, which
had stopped working. By the time I got there, she had already
installed a new switch, but it still wouldn't work. .It's a one-way
switch, controlling two wall fixtures.

The house (which is in the USA) is about sixty years old and has two-
prong plugs, everywhere. The light switch has two screws, with a
black wire to each screw. There are two white wires in the switch
box, spliced together (and they had obviously been that way for many
years). One lamp fixture has two black and two white wires, with the
two blacks connected to the fixture's black wire and the two whites
connected to the fixture's white wire. The other fixture has one
white and one black going to it. So far, so good. Apparently, the
fixtures' wiring is somewhat newer than the rest of the house's
wiring, because they also each have a ground, which is connected to
each box, mounting plate, and fixture housing.

I couldn't see anything that was obviously wrong. And the light
fixtures and the old switch had been working for years. So I used my
multimeter (Tektronix DMM916) and did some very basic measurements,
but will probably need to go back and do some more. Anyway, here is
what I have measured, so far:

With the switch on, and no bulbs installed in the fixtures, the
voltage (VAC RMS) across the switch terminals is very low, i.e.
approx .04 VAC. At each fixture, white-to-ground measured 54 VAC,
black-to-ground measured 120 VAC, and black-to-white measured 34 VAC.

WITH bulbs installed, and the switch ON, both white-to-ground and
black-to-ground measured 120 VAC, and black-to-white measured anywhere
from 14.6 VAC to 18VAC on the first fixture and about .04 VAC on the
second fixture.

But, after emptying some dead insects out of the first fixture, it,
too, measured .04 VAC from black-to-white. (I neglected to measure it
again, without bulbs, to see if the 34VAC from black-to-white had then
changed.) The black-to-white measurements without bulbs also matched
the measurements between the socket bases and threaded bulb holders.

With the switch OFF (both before and after emptying-out the insects in
the first fixture), the voltage across the switch terminals (two
blacks) was about 70 to 76 VAC (varied between measurements).

Also, with the switch off, the resistances, at the fixtures, between
any two of black, white, and ground all appeared to be infinite, as
did the resistances between the socket bases and threaded portions..

Can anyone figure out what's going on, from that? Or, what else
should I measure, or try?

Could it be a problem in the breaker box, itself? I did happen to
notice, about six months ago, that her breaker box was open, slightly
(not the door, the whole front panel!). But it appears to be closed-
up OK, now. The breakers look very old, though. Also, everything
else in the house appears to be working as it always has. And that
circuit does not have its own breaker.

Any DIY suggestions will be appreciated.

- Tom Gootee

wrote in message
...
A friend asked me to help her repair her bathroom light switch, which
had stopped working. By the time I got there, she had already
installed a new switch, but it still wouldn't work. .It's a one-way
switch, controlling two wall fixtures.

The house (which is in the USA) is about sixty years old and has two-
prong plugs, everywhere. The light switch has two screws, with a
black wire to each screw. There are two white wires in the switch
box, spliced together (and they had obviously been that way for many
years). One lamp fixture has two black and two white wires, with the
two blacks connected to the fixture's black wire and the two whites
connected to the fixture's white wire. The other fixture has one
white and one black going to it. So far, so good. Apparently, the
fixtures' wiring is somewhat newer than the rest of the house's
wiring, because they also each have a ground, which is connected to
each box, mounting plate, and fixture housing.

I couldn't see anything that was obviously wrong. And the light
fixtures and the old switch had been working for years. So I used my
multimeter (Tektronix DMM916) and did some very basic measurements,
but will probably need to go back and do some more. Anyway, here is
what I have measured, so far:

With the switch on, and no bulbs installed in the fixtures, the
voltage (VAC RMS) across the switch terminals is very low, i.e.
approx .04 VAC. At each fixture, white-to-ground measured 54 VAC,
black-to-ground measured 120 VAC, and black-to-white measured 34 VAC.

WITH bulbs installed, and the switch ON, both white-to-ground and
black-to-ground measured 120 VAC, and black-to-white measured anywhere
from 14.6 VAC to 18VAC on the first fixture and about .04 VAC on the
second fixture.

But, after emptying some dead insects out of the first fixture, it,
too, measured .04 VAC from black-to-white. (I neglected to measure it
again, without bulbs, to see if the 34VAC from black-to-white had then
changed.) The black-to-white measurements without bulbs also matched
the measurements between the socket bases and threaded bulb holders.

With the switch OFF (both before and after emptying-out the insects in
the first fixture), the voltage across the switch terminals (two
blacks) was about 70 to 76 VAC (varied between measurements).

Also, with the switch off, the resistances, at the fixtures, between
any two of black, white, and ground all appeared to be infinite, as
did the resistances between the socket bases and threaded portions..

Can anyone figure out what's going on, from that? Or, what else
should I measure, or try?



It seems that the white wire is not connected somewhere. It should go all
the way back to the braker box and hook to the neutral side of the wiring.
It may have came apart in the switch box when the switch was replaced.

At no time should the white wire have any voltage on it to the ground. With
the meter you may see some of the induced voltage , but it should not be 120
volts. Sometimes the white wire will be used in a switched circuit, but
should be marked with tape to indicate that..

Check to see if a GFI outlet nearby tripped. It could be feeding that
switch.

You need to check voltage from the hot wire on the switch to the two
neutrals that are spliced together. If you get 120 v, you have an open
neutral between that box and the first lighting outlet. If you don't get
120v, you have an open neutral wire somewhere upstream of the switch box. I
would check nearby outlets and switches for the bad connection. It could be
an upstream GFCI, if one exists, but not likely as that would disconnect the
hot leg to your circuit.



wrote in message
...
A friend asked me to help her repair her bathroom light switch, which
had stopped working. By the time I got there, she had already
installed a new switch, but it still wouldn't work. .It's a one-way
switch, controlling two wall fixtures.

The house (which is in the USA) is about sixty years old and has two-
prong plugs, everywhere. The light switch has two screws, with a
black wire to each screw. There are two white wires in the switch
box, spliced together (and they had obviously been that way for many
years). One lamp fixture has two black and two white wires, with the
two blacks connected to the fixture's black wire and the two whites
connected to the fixture's white wire. The other fixture has one
white and one black going to it. So far, so good. Apparently, the
fixtures' wiring is somewhat newer than the rest of the house's
wiring, because they also each have a ground, which is connected to
each box, mounting plate, and fixture housing.

I couldn't see anything that was obviously wrong. And the light
fixtures and the old switch had been working for years. So I used my
multimeter (Tektronix DMM916) and did some very basic measurements,
but will probably need to go back and do some more. Anyway, here is
what I have measured, so far:

With the switch on, and no bulbs installed in the fixtures, the
voltage (VAC RMS) across the switch terminals is very low, i.e.
approx .04 VAC. At each fixture, white-to-ground measured 54 VAC,
black-to-ground measured 120 VAC, and black-to-white measured 34 VAC.

WITH bulbs installed, and the switch ON, both white-to-ground and
black-to-ground measured 120 VAC, and black-to-white measured anywhere
from 14.6 VAC to 18VAC on the first fixture and about .04 VAC on the
second fixture.

But, after emptying some dead insects out of the first fixture, it,
too, measured .04 VAC from black-to-white. (I neglected to measure it
again, without bulbs, to see if the 34VAC from black-to-white had then
changed.) The black-to-white measurements without bulbs also matched
the measurements between the socket bases and threaded bulb holders.

With the switch OFF (both before and after emptying-out the insects in
the first fixture), the voltage across the switch terminals (two
blacks) was about 70 to 76 VAC (varied between measurements).

Also, with the switch off, the resistances, at the fixtures, between
any two of black, white, and ground all appeared to be infinite, as
did the resistances between the socket bases and threaded portions..

Can anyone figure out what's going on, from that? Or, what else
should I measure, or try?

Could it be a problem in the breaker box, itself? I did happen to
notice, about six months ago, that her breaker box was open, slightly
(not the door, the whole front panel!). But it appears to be closed-
up OK, now. The breakers look very old, though. Also, everything
else in the house appears to be working as it always has. And that
circuit does not have its own breaker.

Any DIY suggestions will be appreciated.

- Tom Gootee

Mike,

If a GFI had tripped would there still be 120 v at the light switch?

Dave M.

On Jan 25, 8:45*am, "David L. Martel" wrote:
Mike,

* *If a GFI had tripped would there still be 120 v at the light switch?

Dave M.

He never actually says theres 120V at the switch, he says he gets 0V
across the switch when on, and 76V when the switch is off. What should
be done is to check the voltage across the black and white feed at the
switch ( switch removed, just measuring the incoming feed).
What would help is to get a test light, like a pigtail with a bulb in
it, and test from point to point. You really don't need to measure
resistances. Either you have an open or not.

"RBM" wrote in message
...
You need to check voltage from the hot wire on the switch to the two
neutrals that are spliced together. If you get 120 v, you have an open
neutral between that box and the first lighting outlet. If you don't get
120v, you have an open neutral wire somewhere upstream of the switch box.
I
would check nearby outlets and switches for the bad connection. It could
be
an upstream GFCI, if one exists, but not likely as that would disconnect
the
hot leg to your circuit.



wrote in message
...
A friend asked me to help her repair her bathroom light switch, which
had stopped working. By the time I got there, she had already
installed a new switch, but it still wouldn't work. .It's a one-way
switch, controlling two wall fixtures.

The house (which is in the USA) is about sixty years old and has two-
prong plugs, everywhere. The light switch has two screws, with a
black wire to each screw. There are two white wires in the switch
box, spliced together (and they had obviously been that way for many
years). One lamp fixture has two black and two white wires, with the
two blacks connected to the fixture's black wire and the two whites
connected to the fixture's white wire. The other fixture has one
white and one black going to it. So far, so good. Apparently, the
fixtures' wiring is somewhat newer than the rest of the house's
wiring, because they also each have a ground, which is connected to
each box, mounting plate, and fixture housing.

I couldn't see anything that was obviously wrong. And the light
fixtures and the old switch had been working for years. So I used my
multimeter (Tektronix DMM916) and did some very basic measurements,
but will probably need to go back and do some more. Anyway, here is
what I have measured, so far:

With the switch on, and no bulbs installed in the fixtures, the
voltage (VAC RMS) across the switch terminals is very low, i.e.
approx .04 VAC. At each fixture, white-to-ground measured 54 VAC,
black-to-ground measured 120 VAC, and black-to-white measured 34 VAC.

WITH bulbs installed, and the switch ON, both white-to-ground and
black-to-ground measured 120 VAC, and black-to-white measured anywhere
from 14.6 VAC to 18VAC on the first fixture and about .04 VAC on the
second fixture.

But, after emptying some dead insects out of the first fixture, it,
too, measured .04 VAC from black-to-white. (I neglected to measure it
again, without bulbs, to see if the 34VAC from black-to-white had then
changed.) The black-to-white measurements without bulbs also matched
the measurements between the socket bases and threaded bulb holders.

With the switch OFF (both before and after emptying-out the insects in
the first fixture), the voltage across the switch terminals (two
blacks) was about 70 to 76 VAC (varied between measurements).

Also, with the switch off, the resistances, at the fixtures, between
any two of black, white, and ground all appeared to be infinite, as
did the resistances between the socket bases and threaded portions..

Can anyone figure out what's going on, from that? Or, what else
should I measure, or try?

Could it be a problem in the breaker box, itself? I did happen to
notice, about six months ago, that her breaker box was open, slightly
(not the door, the whole front panel!). But it appears to be closed-
up OK, now. The breakers look very old, though. Also, everything
else in the house appears to be working as it always has. And that
circuit does not have its own breaker.



In addition to what RBM said, I would suggest that you stop using that
multimeter and just use a pigtail socket and standard light bulb to test the
wires. The results will be more definitive. All of those odd voltages that
a multimeter displays just confuses a do-it-yourselfer.

On Thu, 24 Jan 2008 22:42:28 -0800 (PST), wrote:

A friend asked me to help her repair her bathroom light switch, which
had stopped working. By the time I got there, she had already
installed a new switch, but it still wouldn't work. .It's a one-way
switch, controlling two wall fixtures.

The house (which is in the USA) is about sixty years old and has two-
prong plugs, everywhere. The light switch has two screws, with a
black wire to each screw. There are two white wires in the switch
box, spliced together (and they had obviously been that way for many
years). One lamp fixture has two black and two white wires, with the
two blacks connected to the fixture's black wire and the two whites
connected to the fixture's white wire. The other fixture has one
white and one black going to it. So far, so good. Apparently, the
fixtures' wiring is somewhat newer than the rest of the house's
wiring, because they also each have a ground, which is connected to
each box, mounting plate, and fixture housing.

I couldn't see anything that was obviously wrong. And the light
fixtures and the old switch had been working for years. So I used my
multimeter (Tektronix DMM916) and did some very basic measurements,
but will probably need to go back and do some more. Anyway, here is
what I have measured, so far:

With the switch on, and no bulbs installed in the fixtures, the
voltage (VAC RMS) across the switch terminals is very low, i.e.
approx .04 VAC. At each fixture, white-to-ground measured 54 VAC,
black-to-ground measured 120 VAC, and black-to-white measured 34 VAC.

WITH bulbs installed, and the switch ON, both white-to-ground and
black-to-ground measured 120 VAC, and black-to-white measured anywhere
from 14.6 VAC to 18VAC on the first fixture and about .04 VAC on the
second fixture.

But, after emptying some dead insects out of the first fixture, it,
too, measured .04 VAC from black-to-white. (I neglected to measure it
again, without bulbs, to see if the 34VAC from black-to-white had then
changed.) The black-to-white measurements without bulbs also matched
the measurements between the socket bases and threaded bulb holders.

With the switch OFF (both before and after emptying-out the insects in
the first fixture), the voltage across the switch terminals (two
blacks) was about 70 to 76 VAC (varied between measurements).

Also, with the switch off, the resistances, at the fixtures, between
any two of black, white, and ground all appeared to be infinite, as
did the resistances between the socket bases and threaded portions..

Can anyone figure out what's going on, from that? Or, what else
should I measure, or try?

Could it be a problem in the breaker box, itself? I did happen to
notice, about six months ago, that her breaker box was open, slightly
(not the door, the whole front panel!). But it appears to be closed-
up OK, now. The breakers look very old, though. Also, everything
else in the house appears to be working as it always has. And that
circuit does not have its own breaker.

Any DIY suggestions will be appreciated.

- Tom Gootee

I would break the white wire at the switch and then test between the
hot and the white.

120V there will tell you that the problem is in the circuit going to
the light. If you don't have 120V there then the problem is in the
circuit going home.

You have a bad connection in the white somewhere.

"John Grabowski" wrote in message
...
In addition to what RBM said, I would suggest that you stop using that
multimeter and just use a pigtail socket and standard light bulb to test
the
wires. The results will be more definitive. All of those odd voltages
that
a multimeter displays just confuses a do-it-yourselfer.


Those digital meters are about the worse test device a home owner can use.
They do seem to give all kind of funny voltages, even when there is no real
connection involved. That is probably where the 54 and 34 volts are comming
from . Also that .04 volts is not worth mentioning, just say zero volts.

I work as an electrician and instrument technician at a large plant. I have
a $ 300 digital meter, but mostly use the old Simpson 260 analog meter for
simple tests. I have also used the light bulb and pigtail. Usually get
laughed at by the co-workers when I pull that out, but it usually finds the
problem where the others fail with their digital meters.

You have to know what to expect when using any test device.

In article ,
"Ralph Mowery" wrote:

You have to know what to expect when using any test device.

No ****. They should make you take a basic comprehension test of circuit
fundamentals before they sell you one of those things. Why do people
think they can use a meter in any useful way without understanding what
the hell they're doing? The OP could be using an ignition timing light
and learn about the same amount of useful information about that pesky
circuit as he knows now with all his 34 volts and 0.04 volt stuff.

Every time I read posts where people are testing circuits with a variety of
multi meters, I've been tempted to tell them to chuck the meter and get a
pigtail socket. Like Ralph, and you, I've got all manner of test equipment,
but the pigtail or wiggy tell me everything I need to know, almost all the
time. It's simple and it works




"John Grabowski" wrote in message
...

"RBM" wrote in message
...
You need to check voltage from the hot wire on the switch to the two
neutrals that are spliced together. If you get 120 v, you have an open
neutral between that box and the first lighting outlet. If you don't get
120v, you have an open neutral wire somewhere upstream of the switch box.
I
would check nearby outlets and switches for the bad connection. It could
be
an upstream GFCI, if one exists, but not likely as that would disconnect
the
hot leg to your circuit.



wrote in message
...
A friend asked me to help her repair her bathroom light switch, which
had stopped working. By the time I got there, she had already
installed a new switch, but it still wouldn't work. .It's a one-way
switch, controlling two wall fixtures.

The house (which is in the USA) is about sixty years old and has two-
prong plugs, everywhere. The light switch has two screws, with a
black wire to each screw. There are two white wires in the switch
box, spliced together (and they had obviously been that way for many
years). One lamp fixture has two black and two white wires, with the
two blacks connected to the fixture's black wire and the two whites
connected to the fixture's white wire. The other fixture has one
white and one black going to it. So far, so good. Apparently, the
fixtures' wiring is somewhat newer than the rest of the house's
wiring, because they also each have a ground, which is connected to
each box, mounting plate, and fixture housing.

I couldn't see anything that was obviously wrong. And the light
fixtures and the old switch had been working for years. So I used my
multimeter (Tektronix DMM916) and did some very basic measurements,
but will probably need to go back and do some more. Anyway, here is
what I have measured, so far:

With the switch on, and no bulbs installed in the fixtures, the
voltage (VAC RMS) across the switch terminals is very low, i.e.
approx .04 VAC. At each fixture, white-to-ground measured 54 VAC,
black-to-ground measured 120 VAC, and black-to-white measured 34 VAC.

WITH bulbs installed, and the switch ON, both white-to-ground and
black-to-ground measured 120 VAC, and black-to-white measured anywhere
from 14.6 VAC to 18VAC on the first fixture and about .04 VAC on the
second fixture.

But, after emptying some dead insects out of the first fixture, it,
too, measured .04 VAC from black-to-white. (I neglected to measure it
again, without bulbs, to see if the 34VAC from black-to-white had then
changed.) The black-to-white measurements without bulbs also matched
the measurements between the socket bases and threaded bulb holders.

With the switch OFF (both before and after emptying-out the insects in
the first fixture), the voltage across the switch terminals (two
blacks) was about 70 to 76 VAC (varied between measurements).

Also, with the switch off, the resistances, at the fixtures, between
any two of black, white, and ground all appeared to be infinite, as
did the resistances between the socket bases and threaded portions..

Can anyone figure out what's going on, from that? Or, what else
should I measure, or try?

Could it be a problem in the breaker box, itself? I did happen to
notice, about six months ago, that her breaker box was open, slightly
(not the door, the whole front panel!). But it appears to be closed-
up OK, now. The breakers look very old, though. Also, everything
else in the house appears to be working as it always has. And that
circuit does not have its own breaker.



In addition to what RBM said, I would suggest that you stop using that
multimeter and just use a pigtail socket and standard light bulb to test
the
wires. The results will be more definitive. All of those odd voltages
that
a multimeter displays just confuses a do-it-yourselfer.