power bleed through half switches

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tony b

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when half switch is off my tester shows a dim lite volt meter shows 29 volts where in code or industry standards is this allowable and how do i correct? :confused:
 
Re: power bleed through half switches

an outlet where bottm stays hot break the tab and top on a switch
 
Re: power bleed through half switches

That sounds like a 1/4 switch, shouldn't a 1/2 switch be 60 v.?

I'm just kidding, I couldn't resist. :D
 
Re: power bleed through half switches

30 volts sounds like something you'd get between two loads where one is connected to one leg and the other is connected to the other leg or neutral.
 
Re: power bleed through half switches

You are probably just picking up a ghost voltage due to capacitance. There is no need to worry about it.

Your wiggy aka solenoidal voltage tester is a better tester to use because it is not suseptible to ghost voltage.


While in school, my instructor did a demonstration using a digital multi meter to show this effect. The instructor plugged one probe into and outlet, and had a student (me) hold the other probe. Touching the wall and the dry erase board caused the reading to go up as we increased the plate area of the capacitor. We actually got a reading of over 100 volts.
 
Re: power bleed through half switches

peter d this is not just one but 6 in whole house another house i'm building down the street only one shows ableed but the other 5 shows nothing we are about to close on this house and the owner is concernd from his inspection walk and may not sign off
 
Re: power bleed through half switches

Tony in my opinion Peter D nailed it.

It has nothing to do with the switch at all. It has to do with the circuit wiring and it is harmless.

Plug any load into that outlet and the 30 volts will be gone.

Digital multimeters are much more sensitive than needed for this type of work.
 
Re: power bleed through half switches

Tony, if it really troubles you, don't use 14-3 for the job. But it's a benign peculiarity. :D

I thought this was "induced" voltage, not "capacitance"? Perhaps I have my terms confused.
 
Re: power bleed through half switches

I sometimes have to use a light bulb because capacitance in a switch loop will mislead a voltmeter.

I happen to have a rubber socket with a white light bulb. I also have a harness with 4 rubber sockets and red, green, blue, and yellow bulbs in it. Great for ringing out stuff and other troubleshooting.
 
Re: power bleed through half switches

Originally posted by georgestolz:


I thought this was "induced" voltage, not "capacitance"? Perhaps I have my terms confused.
Click to expand...
Both capacitance and inductance can cause ghost voltages. As Bob said, the solution is to turn the votlage into current, and it disppears. or not use multiwire circuits. :roll:
 
Re: power bleed through half switches

That ghost voltage as stated will not be there when using an old fasion wiggy,but my fluke has taught me that when there is 27 to 29 volts present at the half switched receptacle that is normal and this isn`t a multi wired circuit. Same situation but the 3 way 1/2 switched receptacle now reads 37 to 40 volts go to the multi gang box where both travellers and switch feed are coming from and you`ll find the switch wire and travellers cut in wrong.Just something I have found out after a few 1000 hot checks ;)
 
Re: power bleed through half switches

Originally posted by peter d:
As Bob said, the solution is to turn the votlage into current, and it disppears. or not use multiwire circuits. ;)

I assume the phenomenon to be caused by the twisting of 14-3 creating a wanna-be transformer, which induces the voltage onto the "switched" receptacle's conductor when it's "off".

That would be induction, not capacitance, right?
Click to expand...
 
Re: power bleed through half switches

Originally posted by georgestolz:
It's not a multiwire circuit,
Click to expand...
Actually we do not know if it's a multiwire circuit or not, it is also irrelevant. :p


Originally posted by georgestolz:
I assume the phenomenon to be caused by the twisting of 14-3 creating a wanna-be transformer,
Click to expand...
It can happen with twisted or untwisted conductors.

When I check a 'dead' conductor in a long raceway with live 277 conductors I have seen as much as a 100 volts on the 'dead' one. :roll:

Much better to get out the "Wiggys" or other solenoid type tester.

Originally posted by georgestolz:
That would be induction, not capacitance, right?
Click to expand...
I don't know, I always called it induction but have read that it is 'capacitance coupling'

Either way the false readings can be annoying.
 
Re: power bleed through half switches

It would be induction. :)

Edit: Hmm. Capacitive coupling could transfer current too if not DC.

Edit: and inuction isn't a word, I'll have to fix that. That would be an A error.

[ June 15, 2005, 02:17 AM: Message edited by: physis ]
 
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