Was working on a circuit the other day and as always I test for power first. I got a reading of 75 volts on one circuit I was working on. Unsure why I’d see such a thing I looked for another circuit (I needed to find a 120v circuit to tap into for a receptacle). The owner asked since there was a dead wall switch nearby could I wire the receptacle to the switch. Sure I said. I opened the box and found there was 120v of power there already connected to the switch. I found the wire leading from the switch, it was dead ended in the drop ceiling and wire nutted. With switch off I got 0v. Switch on I read 108 volts, not 120. The wire from the switch tothe ceiling was no more than 8 feet.
What can explain such abnormal voltage drops?
If at first you don’t succeed, try using a hammer next time…everything needs some extra persuasion from time to time. -ME
Replies
Corrosion, even tarnished tips on your test probes...
....are you testing to the neutral or the box...or you got crap on the wires.....
.... what Paul said.
..what do you have at the ####service?
Edited 1/27/2006 11:19 am by maddog3
My probes are new and clean.
240v at service entrance. If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time. -ME
sometimes a gummy splice will read low....what is the hot to neutral at the service........
120If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time. -ME
Willie... you're not getting a 12v drop over 8 feet of wire. There has to be a high resistance in there somewhere (either on the neutral or live), bad connection, tarnished wire... sumthin. Maybe even pitted contacts in the switch. No other reasonable explanation.
Edited 1/27/2006 12:19 pm ET by PaulBinCT
that's funny........right behind ya both times
Great minds... ;)
....;>)
old switch.....crummy connections / splices...hang a pigtail at the ceiling box...I sometimes expose clean wire if the reading is a little low....
Probably the circuit is open and you're just reading hum pickup with your high impedance meter.
happy?
Probably not the problem but years ago I had some really strange readings when I had a great thought. As the house had been built in the early 70's I asked if the wiring into the house was aluminum and they said yes. ( I had been checking some wires that were in fact copper). The owners called the utility company and cut the power and ended up replacing the service wire to copper. Since then I heard of some wild readings with aluminum.
roger