Phantom Voltage

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brian john

Senior Member
Location
Leesburg, VA
I have a job where I was called in to explain why the electrical inspector had an partial indication on his Ideal Bug Eye Tester Model 61-501. This is on a 3 wire to a receptacle switch leg, hot and neutral to a split receptacle top switched, bottom hot continuously.

I am sure this is phantom voltage, utilizing a Fluke I read depending on what condo I am in anywhere from 24 VAC to 84 VAC. I read it on a Fluke 87, Fluke 435 (scope meter 60 hZ sine wave), connect a 12 VDC lamp (tungsten filament) and the lamp does not light, wiggy does not light, analog Simpson meter shows voltage. All readings go away when the lamp is connected or when a wiggy is connected or when I physically connect with my fingers across the de-energized hot to neutral or de-energized hot to ground

My questions to all:

Have you ever used a Ideal 61-501 on a circuit with phantom readings? I will purchase this over the weekend and perform some test on Monday. In addition I will contact Ideal technical support.

Have you ever used a analog Simpson meter on a circuit with phantom readings?

Any insight, links or input will be appreciated.


Not to stop any thoughts but I am familiar with phantom readings and have cleared up countless readings concerns by electrical contractors, my question is mainly regarding the Ideal and Simpson picking up the phantom voltage. And LINKS to technical data

This issue has ground to a halt a large condo project, where the inspector refuses to pass any of the units.
 

buddhakii

Senior Member
Location
Littleton, CO
If you read 84 volts with a fluke, let alone several fluke meters, you may have some issues. Did you check from neutral to ground? Could be backfeed from a contactor or something. You may have neutrals from different circuits tied together.
 

brian john

Senior Member
Location
Leesburg, VA
budd:

Have you ever been involved with or are aware of the issue commonly referred to as phantom voltages?


I should add a THROUGH inspection was made of the distribution system from the utility transformers to the outlets, I believe after careful investigation this is a phantom issue. But I can be swayed the other way if someone can give insight into the Simpson/Ideal issue?

No back feed, no grounding issue, only an issue with 3 wire NM cable when one conductor is de-energized.
 
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buddhakii

Senior Member
Location
Littleton, CO
I don't think I've run into it since I was an apprentice, but I do remember something about it. Did a little research on phantom voltage here and learned a lot about it. This is a great forum that humbles me almost every day.
 

brian john

Senior Member
Location
Leesburg, VA
Test.

50' 12-3 extension cord Black conductor connected to 20 amp CB at 120 VAC, Neutral connected to ground conductor termination bar in panel. Ground not terminated on either end. Prior to the test the extension cord was meggered black to white 18.2 gig, black to green 22.3 Gig white to green 19.1 Gig for one minute each at 1000 VDC

Hot to neutral (black to white)

Fluke 87 121.7 VAC
Simpson 120 VAC

Hot to green

Fluke 87 58.8 VAC
Simpson 60 VAC

Neutral to green

Fluke 87 58.61 VAC
Simpson 60 VAC

Ground Green conductor

Fluke 87 68.06 millivolts
Simpson 0 volts

need to get to HD or Lowe's for a Ideal tester. I assume they will have one of these?
 
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brian john

Senior Member
Location
Leesburg, VA
budd: From that never ending source of reliable knowledge Wikipedia:

Phantom voltage (sometimes referred to as ghost voltage) is voltage that appears in an electrical conductor such as a wire, even though the wire is disconnected from an electrical circuit. The term is often used by electricians, and might be seen, eg, when measuring the voltage at a lighting fixture after removing the bulb. It's not unusual to measure phantom voltages of 50-90 volts when testing the wiring of ordinary 120V circuits.

And then NEMA

http://www.nema.org/stds/eng-bulletins/upload/Bulletin-88.pdf
 

brian john

Senior Member
Location
Leesburg, VA
TEST OVER:

Lowes (closer that HD) had the Ideal 61-501 and I also purchased the 61-086.

The Ideal 61-501 does light up (middle yellow) on phantom voltage. Additionally the Ideal Vol-Con XL 61-086 also has some reading issues with phantom voltages.

Oh well now I have to recreate this for my customer and the electrical inspector to prove what I assumed had to be the case.
 

electricalperson

Senior Member
Location
massachusetts
ive seen pictures of somebody on this forum maybe demonstrating phantom voltage with a coil of 14/3 romex. i believe a low impedance meter wont pick up phantom voltage. my fluke 117 has a low impedance function
 

brian john

Senior Member
Location
Leesburg, VA
TEST OVER:

Lowes (closer that HD) had the Ideal 61-501 and I also purchased the 61-086.

The Ideal 61-501 does light up (middle yellow) on phantom voltage. Additionally the Ideal Vol-Con XL 61-086 also has some reading issues with phantom voltages.

Oh well now I have to recreate this for my customer and the electrical inspector to prove what I assumed had to be the case.


I should say in conclusion that phantom/ghost voltages are evident with several different meters and testers. When in doubt be safe never assume. A wiggy type tester and or light bulb of the proper voltage in a SAFE setup is the ultimate proff of real-phantom/ghost.
 

electricalperson

Senior Member
Location
massachusetts
I should say in conclusion that phantom/ghost voltages are evident with several different meters and testers. When in doubt be safe never assume. A wiggy type tester and or light bulb of the proper voltage in a SAFE setup is the ultimate proff of real-phantom/ghost.

a lot of people get fooled by phantom voltage. the wrong tester for checking for voltage is a DMM. the solenoid testers are best for checking. usually i see it on 14/3 romex and multiple wires in conduit
 

brian john

Senior Member
Location
Leesburg, VA
The Fluke TL225 Stray Voltage Adapter Test Lead Set

The Fluke Stray Voltage Adapter Test Lead Set is an accessory that allows a high impedance multimeter to measure circuits, connections, cables or connectors subject to stray voltages. The adapter provides a low impedance load to the measured circuit, desensitizing the meter to low energy, spurious sources of interference. If the measurement points are energized with a  hard voltage, the meter will simply display the voltage reading. If the measurement points contain a stray or ghost voltage, the meter will read very close to zero volts, indicating the circuit or connection is not energized.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
All readings go away when the lamp is connected or when a wiggy is connected or when I physically connect with my fingers across the de-energized hot to neutral or de-energized hot to ground.
There is the bottom line. There is no electrical issue. The inspector's wrong.

The only issue is a lack of electrical theory in the inspector's background. :roll:
 

buddhakii

Senior Member
Location
Littleton, CO
budd:

Have you ever been involved with or are aware of the issue commonly referred to as phantom voltages?

budd: From that never ending source of reliable knowledge Wikipedia:





You can call me budd if you like, but my name is Chris.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
090206-1920 EST

Brian:

I measured a length of 40 year old Anaconda Dutrax 12-2 with ground between white and black, but with ground unconnected and got about 10 pfd per foot. Newer cable might have a higher capacitance per foot.

The capacitive reactance per 1 ft at 60 Hz is about 265 megohms. For a 50 ft length this is 5.3 megohms. A Fluke 27 has an input impedance of 10 megohms resistive, and a few pfd of capacitance. A Simpson 260, if of recent manufacture, meaning last 50 years, has an input impedance of 5000 ohms per volt. This means on the 250 V range 1,250,000 ohms resistive. Again a few pfd of parallel input capacitance.

Draw the vector diagrams for whatever your actual conditions are to get an estimate of the meter reading.

A good load to lower the input impedance of any meter is a 50 to 100 W 120 V bulb. This provides a shunt resistance of 288 or 144 ohms if the bulb was at full brightness, and 20 or 10 ohms at no illumination.

To fully prove that there is not leakage resistance vs capacitive current you may have to megger the wiring. Another posibility is to measure the AC current with a Fluke 27 and prove how small it is.

You may have to educate the inspector. But, first, you need to make sure there is no DC leakage.

Capacitive reactance is Xc = 1/( 2*Pi*f*C) where Xc is in ohms, f in Hz, and C in farads. One pfd = Farad/10^12,

.
 

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
This issue has ground to a halt a large condo project, where the inspector refuses to pass any of the units.

I really can't even believe it. The inspector is using a cheapo $6 dollar tester with no idea how to interpret the results and that gives him the right to stop the job?!?! GOOD GRIEF!

It's a shame you even had to waste your time to prove him wrong, when it should be the other way around.
 

quogueelectric

Senior Member
Location
new york
Well I do this all the time not phantom voltage but other things and the contractors do pay for my time. Sort of how I make a living.

Brian take the tester and put the volts scale to the lowest scale. Go under a florescent light and separate the leads with your arms as much as you can and watch the numbers fly. This is a good example to show the inspector. An untrained person is not going to know how to interpret the findings of a high impedence voltmeter. I did not think that the simpson analog meter was high impedance per say which worrys me a little. I would have to read the specs of the meter. It would probably have to be to have a reading like that. Does the recept respond to a tic tracer ??
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
090207-0726 EST

quo:

The Simpson is 20,000 ohms/volt on DC (a 50 microamp meter movement), and on AC it is 5,000 ohms/volt.

At the 250 range this translates to 5,000,000 megs DC, and 1.25 megs on AC.

An interesting aside. The other night I compared two Simpson 270 meters with my Fluke 27 on DC and the microamp range. One Simpson is 1961 and the other is later 60s. The 1961 is pivot and jewel, and the other is taut band. All three were within 1/2% at 50 microamps. The 1961 had a slight offset in mid range, otherwise all tracked very well.

My 1947 Simpson 260 reads 100 microamps with 98 as the input. This is still a 20,000 ohms/volt meter, but there was no 50 microamp input selection.

What is amazing is that the meter magnets have been so stable.

.
 
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