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Old 06-11-2019, 07:11 PM   #1
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Voltage only 80v


People,

Have a light switch to a closet bulb, 70's built home. Switch has 2 black wires- one on each side, and coming from 2 separate wires in back of box. Anyway, voltage is only about 79+. It should be a 120v measurement for the light to work, right?

Anyone know what one should do next? I checked one other light switch in the same room, I think its the same circuit, and got 120v.
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Old 06-11-2019, 07:14 PM   #2
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Re: Voltage only 80v


Pull switch out of box. Show picture of switch and wires.
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Old 06-11-2019, 07:19 PM   #3
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Re: Voltage only 80v


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Originally Posted by papereater View Post
People,

Have a light switch to a closet bulb, 70's built home. Switch has 2 black wires- one on each side, and coming from 2 separate wires in back of box. Anyway, voltage is only about 79+. It should be a 120v measurement for the light to work, right?

Anyone know what one should do next? I checked one other light switch in the same room, I think its the same circuit, and got 120v.
Where are you measuring voltage at?
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Old 06-11-2019, 09:00 PM   #4
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Re: Voltage only 80v


You need to be measuring voltage from black to white. If that is what you did then you need to find look for issue in the circuit feeding that box.
could be coming from a receptacle. If that receptacle is connected using back stab connection move the wires to the screws. Back stabs are very common cause of loose connections.
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Old 06-11-2019, 09:14 PM   #5
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Re: Voltage only 80v


What is the voltage at the light with the switch on?
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Old 06-12-2019, 10:08 AM   #6
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Re: Voltage only 80v


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Originally Posted by papereater View Post
People,

Have a light switch to a closet bulb, 70's built home. Switch has 2 black wires- one on each side, and coming from 2 separate wires in back of box. Anyway, voltage is only about 79+. It should be a 120v measurement for the light to work, right?

Anyone know what one should do next? I checked one other light switch in the same room, I think its the same circuit, and got 120v.
How did you measure the voltage? Between the two wires on the switch or between hot and neutral or hot and ground?

Does the closet light work?
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Old 06-12-2019, 03:02 PM   #7
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Re: Voltage only 80v


Sorry for late reply- I measured at the wires themselves, not at the brass screw heads. There is no white wire anywhere. 2 blacks. Light worked before, now bulb died. There is one black wire on right of switch and one black on left of switch, at opposing sides (diagonal).
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Old 06-12-2019, 03:03 PM   #8
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Re: Voltage only 80v


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How did you measure the voltage? Between the two wires on the switch or between hot and neutral or hot and ground?

Does the closet light work?
Good point Mr. I measured at the 2 wires on the switch. Could I measure from one black wire and the steel box for the hot/ground measurement? I dont see any copper ground anywhere.

Light bulb is dead now. worked before.
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Old 06-12-2019, 04:03 PM   #9
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Re: Voltage only 80v


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Good point Mr. I measured at the 2 wires on the switch. Could I measure from one black wire and the steel box for the hot/ground measurement? I dont see any copper ground anywhere.

Light bulb is dead now. worked before.
Assuming the box is grounded through metal conduit or metal armored cable, then yes you can use that as a ground reference.

No offense, but I have seen it before with some of my customers, did you try changing the light bulb? I had one customer who had a whole box of bad light bulbs. When I got a bulb from my truck and put it in her light it worked fine.
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Old 06-12-2019, 06:55 PM   #10
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Re: Voltage only 80v


Thanks, John. You know, I just went back there again and sheesh, now it shows 120v! yes, I did change the bulb. Now I got a new bulb, and it flicks on/off. Its a bad switch. I fiddled with it and Im convinced a new switch will fix it. And, the bulb does light up at times, when the switch is in hick up state. I think Ive (we've) figured this one out!!

I still done get why first I got 80 v. Whatever.
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Old 06-12-2019, 08:13 PM   #11
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Re: Voltage only 80v


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Originally Posted by papereater View Post
Thanks, John. You know, I just went back there again and sheesh, now it shows 120v! yes, I did change the bulb. Now I got a new bulb, and it flicks on/off. Its a bad switch. I fiddled with it and Im convinced a new switch will fix it. And, the bulb does light up at times, when the switch is in hick up state. I think Ive (we've) figured this one out!!

I still done get why first I got 80 v. Whatever.
The 80 volts you were getting was due to the bad switch. You did not have a reference point to check the voltage to
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Old 06-13-2019, 09:10 AM   #12
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Re: Voltage only 80v


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Originally Posted by papereater View Post
Thanks, John. You know, I just went back there again and sheesh, now it shows 120v! yes, I did change the bulb. Now I got a new bulb, and it flicks on/off. Its a bad switch. I fiddled with it and Im convinced a new switch will fix it. And, the bulb does light up at times, when the switch is in hick up state. I think Ive (we've) figured this one out!!

I still done get why first I got 80 v. Whatever.
You may have only read 80 volts because you were reading through the light bulb and not hot to neutral or hot to ground. You had hot to load.

To check for a bad switch next time just remove the wires off the switch and wirenut them together. If the light stays on, the switch is bad.
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