# Headscratching Trouble Shooting Question



## 480sparky (Sep 20, 2007)

Homeowners are notorious for not being able to read a meter accurately. What they may well be seeing is millivolts, not volts.

They just look at the number on the screen, and nothing else.










That's 128.4 volts.















This is not 30 volts. It's 30 _millivolts_. The meter is reading it's own power. Most cheap digital meters will display some sort of 'voltage' reading when there nothing connected. Your HO may believe he's reading 30 volts.

I tried reading your post, and as soon as I saw that the HO was involved in the troubleshooting, I would give little credence to what a HO says. Another problem is your mention of "...I don't remember..." a couple times. Makes it hard to give a definite answer if we don't know all the details.


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## JohnJ0906 (Jan 22, 2007)

Could be phantom voltage as well.

http://www.snapdrive.net/files/507790/UL NEMA documents/PhantomVoltage.doc

Did you replace the switches?


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## Kletis (Jan 18, 2008)

Is this an illuminated switch? Probably not considering that it is for a disposal, but I know that you will read voltage over an illuminated switch when it is off.


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## Jupe Blue (Aug 18, 2008)

I don't think that it's a meter reading issue. I read 10v switch leg to ground using my Fluke multimeter. 

I haven't yet replaced any switches. I am reading this voltage on at least 4 different switch locations throughout the house. 


480sparky - I have worked in this customers house for 20+ hours - sorry, over the course of that time, I couldn't remember whether I took a voltage reading at a given point or how a particular device was wired. There are plenty of details to address my question in my original post.

JohnJ0906- thanks for the link. I'll read the paper more closely to see if adds some insight into my problem. Do think I can tell the HO that it's a equipment issue and not an electrical problem? 

What do any of you think about HO's noting that the compact fluorescent lights flicker/flash when the switches are off?


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## brian john (Mar 11, 2007)

480:

Ever go to read a circuit that should be dead you traced the circuit and turned off the power and see 127 mv and miss the mv for a second, blows you mind.


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## Slider (Jun 3, 2008)

Could some of your voltage be coming from a bad neutral? Maybe your voltage is on your neutral. Maybe have power company do load test at meter and see what is found.


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## brian john (Mar 11, 2007)

Slider said:


> Could some of your voltage be coming from a bad neutral? Maybe your voltage is on your neutral. Maybe have power company do load test at meter and see what is found.


Brains rule of solving electrical issues.

NEVER NEVER NEVER rely on any one else to solve your problem, they'll just screw it up and number one on the list of screw up is the UTILITY.

I'll work with someone if necessary, but how you ever going to learn if someone else does it and typically they'll not do it properly.

UNLESS YOU ARE HIRING ME. cause I'll show you how I screwed up.


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## gilbequick (Oct 6, 2007)

I take what the homeowner says is wrong as a rough guideline as to what's really going on. Many times what they say will lead you on a wild goose chase. They might be able to tell you what's happening but it's pretty rare they have a decent clue why. The only way to know what's really going on is to go there and check it out yourself.


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## Slider (Jun 3, 2008)

Let me clarify. If you actually see the problem yourself maybe check for a neutral issue. I would not believe what anyone tells me without seeing it. If the power company does a load test you need to be standing right there reading the meter.


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## Jupe Blue (Aug 18, 2008)

Maybe I wasn't clear on the original post. I (the electrician, not the homeowner) did the following:

Here's what I have done so far:

Verified voltage reading initially. 10v - switch leg to neutral when switch is off; 120v switch leg to neutral when switch is on. Initially, no ground wire in circuit.

Refed the kitchen lights with new grounded circuit. Still had 10v. switch leg to neutral and now had 10v. switch leg to ground when off. 120v when switch is on.

Denergized all other circuits in house, removed all other neutrals and grounds (other than kitchen lighting circuit) from neutral/ground bar in panel. Problem persisted with all other circuits off/neutrals disconnected.

Checked neutral connections at panel and meter base. Connections tight and and no visual evidence of damaged wires.

Disconnected grounding/bonding wire to water pipe, gas pipe and ground rod (can only verify one ground rod). Zero potential between feeder neutral and grounding wires. 120v. between both phase legs and grounding wire. 120v between both phases and neutral. 240 volts phase to phase.

Let's leave the HO statements out of this and see if there are any theories out there about the problem.

Guys in my shop have suggested:

Bad main breaker
Damage overhead feeder from POCO transformer to meter base
Bad Switches
Faulty meters (phantom voltages)

Any of these seem reasonable?


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## 480sparky (Sep 20, 2007)

brian john said:


> 480:
> 
> Ever go to read a circuit that should be dead you traced the circuit and turned off the power and see 127 mv and miss the mv for a second, blows you mind.


I do that too. That's why a HO may never see that little 'm'. Even if they do, they usually ignore it.




brian john said:


> Brains rule of solving electrical issues.....


Who is Brain?


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## brian john (Mar 11, 2007)

Brian = Brain just check my 4th grade report card. School would not make a mistake.


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## surfbh (Jun 1, 2008)

Personally, I'd disconnect the fixtures and temporarily hook up others in their place and retest. If still having problems I'd put the circuit on a different breaker. I'd change out the switch if still having problems. I am assuming you pulled all new wire from the panel to all these lights right?


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## Jupe Blue (Aug 18, 2008)

surfbh - yes, new wire for the lighting circuit. Will try new switches next.


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## 76nemo (Aug 13, 2008)

Jupe Blue said:


> I don't think that it's a meter reading issue. I read 10v switch leg to ground using my Fluke multimeter.
> 
> I haven't yet replaced any switches. I am reading this voltage on at least 4 different switch locations throughout the house.
> 
> ...


 
You read 10V on your Fluke "HIGH IMPEDANCE" input meter, VoltSticks will do the same. A solenoid tester or a meter like Fluke's 116 and 117 have dual impedance selection. It's very obvious that one function alone would have saved you alot of headache here:icon_wink:


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## brian john (Mar 11, 2007)

JUpe you were clear did you read our responses REGARDINBG PHANTOM VOLTAGES.


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## bobelectric (Feb 24, 2007)

brian john said:


> Brains rule of solving electrical issues.
> 
> NEVER NEVER NEVER rely on any one else to solve your problem, they'll just screw it up and number one on the list of screw up is the UTILITY.
> 
> ...


I learned to be polite and thank the customer for his troubleshooting expertise before he had to call me in.I listen to his probabaly cause,(clock ticking), he's out of the way,look for problem.


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## randomkiller (Sep 28, 2007)

Kletis said:


> Is this an illuminated switch? Probably not considering that it is for a disposal, but I know that you will read voltage over an illuminated switch when it is off.


You will read voltage (potential) across every switch when it's contacts are open.


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## Tiger (Jan 3, 2008)

I did a quick scan of the replies, so excuse me if this is a duplicate. Unusual voltage readings are typically errors from DMMs. Use a wiggy which lightly loads the circuit and gives real readings.

Dave


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## 76nemo (Aug 13, 2008)

Wiggy's are NOT CAT rated, and can be a hazard. Wiggy's can also load some control work in the wrong scenario. Watch your *ss!!!!!!!!


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## Tiger (Jan 3, 2008)

Jupe Blue said:


> Originally went to house...
> Homeowner...
> Almost all lamps in the house...
> Denergized all other circuits in house...


This might be residential.


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## Nodoggie (Oct 17, 2008)

Tiger said:


> This might be residential.


:lol: good call.


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## 2towbot (Nov 19, 2008)

Me thinks POCO conductors and lose the CFLs
just my 2 bits


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## bobelectric (Feb 24, 2007)

Just like I need to know the exact time, I need to know the exact voltage. Fluke,only.


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## cmec (Feb 11, 2008)

Is this overhead or underground lateral and primary?

Bet you the problems on the primary side of utility cos xformer


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## mollydog (Jan 9, 2009)

Hmmm, def a back feed thru the neutral then thru the winding back to load side of switch. But from where... I have seen a neighbors wiring faults come in another homeowners place but you said you lifted the rods and water pipe grounds. I would call the electric utility. Any chance a fault could be from something fed underground? Is there an Uffer ground you dont know of ? If the conditions are right stray voltage from a fault on another property can come in from anywhere because everything has an EG and may have contact somewhere. I dont know but maybe you can try looking beyond your customers property, I never had it myself I learned about it in one of my CE classes. Good Luck


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## lectric_hand6855 (Jan 24, 2009)

I recently wired a new house. The utility company had to run power out to the property, so this was a new service, new transformer, new wire, new meter, new everything. On a new lighting ckt I pulled the hot leg to the ceiling box then pulled a 2c w/g romex to the wall box for the switch leg. With the switch feed tapped to the hot in the ceiling box and the switch return left open in the cieling box I read 10v between the switch return and ground with the switch unhooked. Only thing I could figure out was it was just induced voltage. which may be your problem here?


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## ERIC (Feb 6, 2009)

It Sounds Like A Nuetral Problem.if Your Getting Those Kind Of Readings Check The Lights Wiring To See If Someone "shared" A Nuetral Though A Jb Or Recept Or Switch.10v Is Probably A Backfeed Of Somekind.. Good Luck With It


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## Faultfinder1 (Apr 21, 2009)

*2 cents*

Just my 2 cents worth, as I generally work on the "utility's" side of the cable. If you know exactly what fixtures are on each affected circuit I would work my way backwards along the circuit towards the panel box and try to narrow down the problem voltage readings as best as possible. You could also test at the panel for neutral voltage simply by using your Fluke between the neutral bar and the ground (or a grounded pipe). You shouldn't get any voltage here, obviously. If you do, then the problem is likely on the utility's side. 
Don't know if that helped or not - like i said I'm not that good with residential wiring. I just know the concepts and have alot of experience with the outside stuff!
Good luck.

www.faultlocating.com


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