# It finally paid off



## ICE (May 7, 2014)

https://flic.kr/p/ny6Vog

I have been using a tester for years.  I don't touch anything without first testing it.  Best thirty dollars I've ever spent.

This is on a roof.  I was alone...nobody home either.  That could've knocked me on my :butt or off the roof.

A scary thing about this is that the contractor is one of the better contractors that I deal with regularly.

I will be meeting him there to see what went wrong.


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## chris kennedy (May 7, 2014)

May not be energized, could be no EGC.


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## ICE (May 7, 2014)

Why would it sound off if there isn't voltage present?


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## chris kennedy (May 7, 2014)

If there is no EGC and the unit isn't energized but the ungrounded are, it will go due to capacitive coupling.


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## ICE (May 7, 2014)

Chris,

I'll have to figure out how that works. I wonder if the motor needs to be running for the capacitive coupling to occur?


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## steveray (May 7, 2014)

I had a steel stud wall and door jamb light up like that once.....I just figured it was some kind of cheap tester....


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## Dennis (May 8, 2014)

I would not trust those tester for the presence of voltage.  I have seen many a strange reading from it.  Reading thru the carflex may not work either but thru the metal housing it can.  This does not mean the unit is energized but it could be and certainly you would proceed with caution.

Was the disconnect on or off?


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## Wayne (May 8, 2014)

I was thinking it was ungrounded or maybe an open neutral.


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## ICE (May 8, 2014)

Dennis said:
			
		

> I would not trust those tester for the presence of voltage.  I have seen many a strange reading from it.  Reading thru the carflex may not work either but thru the metal housing it can.  This does not mean the unit is energized but it could be and certainly you would proceed with caution.  Was the disconnect on or off?


I don't know about the disconnect because I didn't touch it.  Once I was back on the ground I shut it off at the service panel.


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## ICE (May 8, 2014)

chris kennedy said:
			
		

> If there is no EGC and the unit isn't energized but the ungrounded are, it will go due to capacitive coupling.


I can't find a layman's explanation of capacitive coupling.  Everything I found was way over my head.

Whatever the case may be, the tester said "don't touch this".  I guess that's as much as I need to know.


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## MASSDRIVER (May 8, 2014)

You can rub those on your shirt and they will sound off.

I get them to go on knob and tube on the neutral if something is disconnected wrong. I guess any small amount of voltage will do it.

Brent.


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## Wayne (May 8, 2014)

Re: It finally paid off



			
				jar546 said:
			
		

> Just testing the photo portion of the website.  Most of you have already seen this picture.


I really liked this explanation.

http://ecmweb.com/content/what-do-you-know-about-capacitive-voltage-sensors


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## ICE (May 8, 2014)

MASSDRIVER said:
			
		

> You can rub those on your shirt and they will sound off.


That's how I checked the old tester to see if it worked.  This one beeps when it's turned on.

It has never gone off on a condenser before and I have found several that lacked an EQG.


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## ICE (May 8, 2014)

Wayne said:
			
		

> I really liked this explanation. http://ecmweb.com/content/what-do-you-know-about-capacitive-voltage-sensors


Thanks Wayne,

I don't think that the tester would sense voltage inside a condenser...grounded or not.  The conductors are just too far from the case....it's nothing like a conduit.

Another odd part is that according to the article that you posted, the tester shouldn't work at all on a roof because it is so far from the Earth.


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## Dennis (May 8, 2014)

ICE said:
			
		

> I can't find a layman's explanation of capacitive coupling.  Everything I found was way over my head.  Whatever the case may be, the tester said "don't touch this".  I guess that's as much as I need to know.


Don't feel bad I can't even pronounce it.  I call it voodoo voltage


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## ICE (May 8, 2014)

> Don't feel bad I can't even pronounce it. I call it voodoo voltage


Apparently, Jeff understands it so it can't be all that complicated.

After reading the article that Wayne provided, I'm not sure that the tester is reliable.


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## Dennis (May 8, 2014)

ICE said:
			
		

> Apparently, Jeff understands it so it can't be all that complicated.After reading the article that Wayne provided, I'm not sure that the tester is reliable.


Those tester are a means to an end but I would not trust it for anything.


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## JPohling (May 9, 2014)

It may give a false positive, but your not going to get shocked using it


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## chris kennedy (May 9, 2014)

False positive isn't nearly as dangerous as a false negative.

That said, if I was an inspector I would definitely carry one.

TL, been 2 days. Did you meet with the EC and have him open that up?


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## Span (May 9, 2014)

I alway thought it reponse to AC magnetic field and if the exiting wiring hot & neutral have crossed connection somewhere than the neutral will have voltage. If this is for kitchen or bathroom circuits the GFCI outlet won't work.


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## ICE (May 9, 2014)

Chris,

Thanks for reminding me.  I called the MC and the receptionist said she would get back to me.

I will continue to use the tester but I now know it's limitations.


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## MASSDRIVER (May 9, 2014)

As an aside, wait till you try to use them on the newly-required-by-some-random-busybody tamperproof outlets.

Monkeys, humping, and footballs. So, so much for easy detection, just haul around your gfci tester.

Brent.


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## ICE (May 13, 2014)

I met with a technician from the company.  He tested with a meter and everything is as it should be.  There is an equipment ground.  The casing is not energized.  My non-contact  tester still sounds off.


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## mmmarvel (May 30, 2014)

ICE said:
			
		

> I met with a technician from the company.  He tested with a meter and everything is as it should be.  There is an equipment ground.  The casing is not energized.  My non-contact  tester still sounds off.


Great BUT - better safe than sorry.  As was posted earlier, I'd rather have a false positive than a false negative.  If it gives me a reading, I need someone with better equipment and more knowledge to assure me that it's safe rather than think that it's a false positive.


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