# Capacitive Phantom Voltage Story



## DipsyDoodleDandy (Dec 21, 2009)

True Story for anyone who cares or hasn't had this happen yet. 

This happened a few years ago and Brian John reminded me of it
Got call from friend at Urgent Care Type facility
Said 1/2 the lights are out and 1/2 are not
Off I went
Starting taking readings. Everything checked out ok yet 1/2 power was out.
480/277v 3 phase 4 wire 400 amp then 75kva transformer into 208/120v Single phase 200 amp panel
Phase to phase and Phase to ground in main panel, transformer, and 208/120 panel all read good. 
Scratching head....for a bit
In the meanwhile called the chief (the old guy who can't wire microwaves) to come out. He was bored at home because he can't get licensed to wire microwaves where he lives so he has nothing to do

In the meanwhile PUCO came out and said everything was good and left.
Shortly after, the Chief shows up and he got the short briefing on symptoms.
Looked at my meter and said "What the heck are you doing with that high impedance piece of crap"
I looked at him puzzled
He whipped out his low impedance meter and took some readings and said phase B at the pad is out and left almost as soon as he got there.
I think he was laughing at me when he was walking away but I couldn't prove it. one of these http://www.farnell.com/datasheets/56836.pdf

I called puco back and he came out but said it's fine. I had to force him to go out at pad and take out the phase b fuse and check. He was reluctant so I had to remind him this was a hospital and there were suffering baby's inside. That made him open the pad. He said wow. Your right. I said yeah...that's because puco gave you one of those cheap high impedance meters. I walked away laughing

Lesson:

Buy a good low impedance meter for backup


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## brian john (Mar 11, 2007)

DipsyDoodleDandy said:


> True Story for anyone who cares or hasn't had this happen yet.
> 
> This happened a few years ago and Brian John reminded me of it
> Got call from friend at Urgent Care Type facility
> ...


I carry ten different meters but for basic trouble shooting I stick with my Knopp, just faster.


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## micromind (Aug 11, 2007)

Same here. There's no phantom voltages with a solenoid-type wiggy. 

In your case, B phase was most likely semi-hot because the 480-120/208 transformer is delta on the primary. 

Rob


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## nolabama (Oct 3, 2007)

Entergy uses Wiggys 'round here.


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## slickvic277 (Feb 5, 2009)

I recommend either a fluke t+pro or a fluke 117(low z option) for trouble shooting.For just the situation you had.:thumbsup:


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## cdnelectrician (Mar 14, 2008)

My T+pro is my most used piece of test equipment!


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## 3phase (Jan 16, 2007)

Slick, we just received Fluke 117's at work. I cannot for the life of me to get my jr man, who is older than I, to use the low Z when he gets an odd voltage reading. For the reasons stated here.


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## brian john (Mar 11, 2007)

One thing I have learned in all my years trouble shooting is there is no one perfect way, what woks for one does not work for another. If something works, you are comfortable with the results and you can make money or save money and you get positive results, I say go for it.


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## Greenblinker (Aug 4, 2008)

I use flukes sv225 stray voltage adapter which plugs into the bottom of my 337 clamp. So far I love it.


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