190 vac from hot leg to switch leg

[Ohms law]

I have 190 vac from constant hot to switch leg when my meter is set to high impedance setting. I have 0 vac when set to low impedence setting. This is a 277vac lighting circuit. There are many florescent and LED fixtures as well. I used a Klein MM2000 DMM. Any advice would be appreciated.

 

[controlled]

What kind of advise are you looking for? Are you troubleshooting something?

 

[Ohms law]

What kind of advise are you looking for? Are you troubleshooting something?

I don't know why I have that voltage, I was looking for a reason why and/or a remedy. There are 3 circuits each have there own neutral running 180feet in pipe then get dispersed with AC cable.

 

[growler]

I have 190 vac from constant hot to switch leg when my meter is set to high impedance setting. I have 0 vac when set to low impedence setting. This is a 277vac lighting circuit. There are many florescent and LED fixtures as well. I used a Klein MM2000 DMM. Any advice would be appreciated.

I'll take a stab at it.

First off I'll assume the switch is not in the circuit (open). Is this correct. If closed you shouldn't read anything unless the switch is bad.

If you go from hot leg (line) to switch leg (load) then you are putting your meter in series with the light fixtures. I'm guessing you would be reading the voltage drop across the resistance of the meter.

Twist you hot wire and switched wire togather and read hot to neutral and see what you get.

 

[Ohms law]

The circuit is open and no light fixture is installed yet. The reason I even checked with my meter was a apprentice said he checked with his voltage detector and said it was still hot with the switch in the off position. This scenario is the same at multiple locations on different 277 vac lighting circuits. I just checked from circuit 3 (B-phase) to circuit 5 (C-phase) with circuit 5 off and read 277 vac on high impedance setting and got 60 vac with low impedance setting. What it's going on. I'm guessing but I wonder if there is a bonding issue at the service. I did not participate in the service installation. I'm not sure.

 

[PetrosA]

If I'm understanding your post right, it sounds like you're getting induced voltages with the circuits running together in the same conduits. It's a "real" voltage, but not necessarily dangerous since there won't be enough current available in a wire with induced voltage to hurt you. The high impedance setting is showing you that voltage while the low impedance setting is introducing a load that "blocks" that voltage from getting to the meter.

 

[Ohms law]

If I'm understanding your post right, it sounds like you're getting induced voltages with the circuits running together in the same conduits. It's a "real" voltage, but not necessarily dangerous since there won't be enough current available in a wire with induced voltage to hurt you. The high impedance setting is showing you that voltage while the low impedance setting is introducing a load that "blocks" that voltage from getting to the meter.

Shouldn't EMT as well as individual neutrals cancel out the induced voltage?

 

[growler]

The circuit is open and no light fixture is installed yet.

If there are no light fixtures installed and you are checking from hot to the switched leg then you should not read anything ( you don't have or shouldn't have a return path for current to flow).

If this switched leg in in conduit are the ends wire nutted off so as not to touch the box?

It really should be the same as holding one of your meter leads out in the air.

Are there other conductors in this conduit that are hot and have current flow?

 

[Ohms law]

I should mention that I shut off circuits 1&3 and left circuit 5 on and I still had the same voltage readings. It did not matter which circuit was off, any combination of off and on between circuits 1,3,5 still resulted in each circuit having these reading unless I shut that specific circuit off.

 

[GoldDigger]

What you are reading is current flowing through the high impedance meter to the capacitance from the open, unconnected switch leg to ground. It is like any other phantom voltage which only appears on a high impedance meter.

 

[Ohms law]

What you are reading is current flowing through the high impedance meter to the capacitance from the open, unconnected switch leg to ground. It is like any other phantom voltage which only appears on a high impedance meter.

But that wouldn't explain why I get 60 volts when I turn my meter to low impedance setting. I also get 60 volts from switch leg to neutral when the switch is off on low impedance setting.

 

[Ohms law]

The circuit is open and no light fixture is installed yet. The reason I even checked with my meter was a apprentice said he checked with his voltage detector and said it was still hot with the switch in the off position. This scenario is the same at multiple locations on different 277 vac lighting circuits. I just checked from circuit 3 (B-phase) to circuit 5 (C-phase) with circuit 5 off and read 277 vac on high impedance setting and got 60 vac with low impedance setting. What it's going on. I'm guessing but I wonder if there is a bonding issue at the service. I did not participate in the service installation. I'm not sure.

Sorry, I had been at work running around dealing with this and other issues, I will try to be more specific with this repost

(high impedance)277 vac reading (low impedance) 60 vac between B-phase (circuit 3/on) and C-phase (circuit 5/off) was done at the panel on the breaker terminals.

The (high impedance)190 vac between hot leg and switch leg when switch is off. (Low impedence) 60 vac between hot leg and switch leg when switch is off.

(high impedence) 60 vac from switch leg to neutral when switch off. (Low impedence) 0vac from switch leg to neutral when switch is off.

 

[GoldDigger]

The hot leg to switch leg low impedance voltage of 60 could be the result of the non linear ballast and lamp combination dropping 217 volts at the current which flows through the series combination of the luminaire and the meter.
Not what you would see with a resistive or incandescent load.

 

[Ohms law]

The hot leg to switch leg low impedance voltage of 60 could be the result of the non linear ballast and lamp combination dropping 217 volts at the current which flows through the series combination of the luminaire and the meter.
Not what you would see with a resistive or incandescent load.

so is this a common issue? I guess I have never ran into a situation with such variance.

Do you think a bonding/grounding issue could possible be a issue?

 

[gar]

141126-2148 EST

Ohms law:

250 ft of #14 Romex measures about 4000 pfd. At 60 Hz the capacitive reactance is about 700,000 ohms. What is the low impedance of your meter? Draw the vectors for 10 M with 0.7 M. What is the expected voltage across the 10 M? Do same for your low impedance.

Assume 15 to 20 pfd per foot for your wire pair, calculate a capacitive reactance for your wire pair, and use that value for my 700,000 ohms.

Find a meter to measure capacitance.

Draw an equivalent circuit and see if you can figure out why your readings may occur.

I have given you smattering of comments wto work from. Do some study.

.

 

[GoldDigger]

I think that it can be explained completely by the combination of phantom voltage and putting a voltmeter in series with a nonlinear
load

 

[FREEBALL]

I have a wiggy I use to check this same situation from time to time maybe this would help. just sayin be safe

 

[cowboy1966]

Sounds like an objectionable current, which can be caused by a broken neutral or a can or panel grounding where it shouldn't. Check all your neutral wires and all your grounding and bonding jumpers.

 

[cowboy1966]

Check for broken neutrals, and recheck all your grounding and bonding jumpers. You are getting what is called an objectionable current

 

[kwired]

I was going to chime in with information about the high voltage measured with high impedance input meter being about the same thing that the non contact tester sees - and is capacitively coupled in origin, but may not have enough power behind it to do any practical work. A low impedance meter will short this weak source out and will read no voltage, but if you are reading 60 volts while using a low impedance meter - you have power available in those conductors - just not sure why at this point. Could even be backfeed into the neutral from another circuit - or even a neutral of a 120 volt circuit could be involved here.