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Light Switch & Fixture Problem
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 |
Light Switch & Fixture Problem
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.. |
Light Switch & Fixture Problem
Check to see if a GFI outlet nearby tripped. It could be feeding that
switch. |
Light Switch & Fixture Problem
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 |
Light Switch & Fixture Problem
Mike,
If a GFI had tripped would there still be 120 v at the light switch? Dave M. |
Light Switch & Fixture Problem
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. |
Light Switch & Fixture Problem
"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. |
Light Switch & Fixture Problem
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Light Switch & Fixture Problem
"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. |
Light Switch & Fixture Problem
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. |
Light Switch & Fixture Problem
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. |
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