Check For Voltage

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Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
I know most, if not all, know this, but if you're like me sometimes you forget simple things.
But please, check for voltage even if the breaker is off. I went on a call today about a clothes dryer not working and breaker tripping. The HO said the breaker had tripped and he reset it. I told him to just leave it on so I could check the voltage at the dryer receptacle. I couldn't get any voltage reading so I went to the panel and shut off the breaker. I then took the cover off the recep. It was burnt pretty bad, almost didn't look like a recep. it was burnt so bad. Anyway, I thought I better check for voltage to be safe. When I touched the probe to one of the line lugs sparks flew and burnt my probe pretty good. I thought, where did that come from? I know I turned the breaker off. I went back to the panel and it was off. I checked for voltage at the breaker terminals and found none.
I went ahead and took the wires off the breaker to check it. This was a combo 2-pole 30/40A breaker for a mobile home. Turns out that probably when the guy said it tripped and he reset it that I don't think it fully tripped. Meaning only 1 pole tripped. The metal piece that is used to operate the breaker had turned a little and had one side wedged so it didn't shut both legs off. I still had 120V at the recep when the sparks flew.

I replaced the burnt receptacle and checked the wiring and checked the breaker as best I could and everything seemed fine after that.
Point is, check, then check, then check again for voltage!
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
Why would sparks fly unless your shorting something to ground?
also, use a voltage pen.

Something did short to ground. I put a probe on one of the terminals and the thing was burnt so bad it crumbled. The insulation on the wire on that side was burnt/melted and when I touched it with the probe it made contact with the ground wire.

I don't trust voltage pen/tic testers when I'm going to have to handle the wires!
 

liquidtite

Senior Member
Location
Ny
ya i dont trust tic testers either ive had many cases were it showed their was voltage when their was none or showed that their was no voltage when 120 was present. if im dealing with 120 ill trust a pen tester any higher voltage i usualy use the probe.i think some guys are crazy trusting the tic tester when dealing with 480/277v it seems risky to me
 

kwired

Electron manager
Location
NE Nebraska
ya i dont trust tic testers either ive had many cases were it showed their was voltage when their was none or showed that their was no voltage when 120 was present. if im dealing with 120 ill trust a pen tester any higher voltage i usualy use the probe.i think some guys are crazy trusting the tic tester when dealing with 480/277v it seems risky to me

I actually trust the pen to be more reliable at a higher voltage.

120 volts can kill you.

Most of us are more likely to run into being more uncertain of whether 120 volts is present than 277. There are those cases sometimes but often if 277/480 is involved it was installed by someone competent and is usually not as big of a mess to figure out as what you run into in dwellings where joe the handiman installed things.
 

the blur

Senior Member
Location
cyberspace
The pen will sometimes pick up a stray or induced voltage, which can be annoying. But I never had a false negative. I find it very reliable.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
The pen will sometimes pick up a stray or induced voltage, which can be annoying. But I never had a false negative. I find it very reliable.

So are you saying that if you used your pen (tic tester) and it didn't go off, you would just grab the wires and go to work?
 

the blur

Senior Member
Location
cyberspace
yes, after I make sure it's working on a known live source. hasn't let me down yet.
I have a few of them, and one is my trusted favorite. The others I don't like or trust.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
yes, after I make sure it's working on a known live source. hasn't let me down yet.
I have a few of them, and one is my trusted favorite. The others I don't like or trust.

I have one and I use it, but it has it's place. IMHO, this isn't one of them.:happyno:
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
The pen will sometimes pick up a stray or induced voltage, which can be annoying. But I never had a false negative. I find it very reliable.
It only takes once, or luckily for me twice. I was in an awkward box above a grid ceiling. I could barely get my hands in an could not see at the same time. I tested my pen tester on a know source, then tested the wires in the box. I then proceeded to uncap the wires. They were hot 277V. It hurt. I checked my tester on a known source again and sure enough it had failed. I have had them where the on switch was not real dependable either. I was originally taught, test your meter on a known live source, check your voltages, and the test your meter on a known live source again. I do this every time now. I will often also use a pen tester and a meter. The pen tester would probably have prevented the meter blowing up in the OP's scenario.
 

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
The pen will sometimes pick up a stray or induced voltage, which can be annoying. But I never had a false negative. I find it very reliable.

Never seen a pen, tic tracer detect or pick up or identify ballanced neutrals. Lots of people get hurt this way.

Common to 277 lighting, or other MWBC, energized & ballanced neutral or ground or grounding is invisible to non-contact sensors.

Where not electrocuted, the ladder fall usually finishes the job.
 
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kwired

Electron manager
Location
NE Nebraska
Never seen a pen, tic tracer detect or pick up or identify ballanced neutrals. Lots of people get hurt this way.

Common to 277 lighting, or other MWBC, energized & ballanced neutral or ground or grounding is invisible to non-contact sensors.

Where not electrocuted, the ladder fall usually finishes the job.

Balancing neutral is not reason why it does not indicate, it is fact that it is a grounded conductor.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
My week for Finding Voltage the Hard Way

My week for Finding Voltage the Hard Way

I'm on a roll for finding voltage in a way I'm not expecting. I was asked to look at a wiring mess left by previous H.O. by a realtor. I won't go into all the mess, but thought this one would go along with this thread pretty good.
There was a keyless fixture in the ceiling with a current tap (receptacle) and pull chain switch combo. I was checking dangling wires that were hanging from ceiling and when I got to the fixture I checked with my tic tester. It showed current but kind of on and off. I then took my meter and checked the recep. outlets that were on the fixture. Boom, about finished off my already burnt probes on my meter. This is what I found when I dropped the fixture down to see what happened.

042.jpg


041.jpg
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
I'm on a roll for finding voltage in a way I'm not expecting. I was asked to look at a wiring mess left by previous H.O. by a realtor. I won't go into all the mess, but thought this one would go along with this thread pretty good.
There was a keyless fixture in the ceiling with a current tap (receptacle) and pull chain switch combo. I was checking dangling wires that were hanging from ceiling and when I got to the fixture I checked with my tic tester. It showed current but kind of on and off. I then took my meter and checked the recep. outlets that were on the fixture. Boom, about finished off my already burnt probes on my meter. This is what I found when I dropped the fixture down to see what happened.

042.jpg


041.jpg

bump
 

kwired

Electron manager
Location
NE Nebraska

Apparently that means begging for a comment. All I have is it looks like the neutral is likely switched conductor for that luminaire. The probe for your meter likely pushed in far enough to contact an ungrounded receptacle terminal as well as the bare grounding conductor.
 

Gac66610

Senior Member
Location
Kansas
got a call years ago in an older home, light works fine til the furnace kicks on, (it was about the same setup only with out the receptacle) turned out that the keyless was being used for the screw in fuse holder
 
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