Question about household wiring

[KEW]

Hey guys, I am replacing a fluorescent overhead kitchen light that quit working.
I assume the ballast went out, but I was kind of looking for an excuse to replace it anyway.

When I apply a multimeter, I get ~36VAC when both of the wall switches are off!
I do get 0V when the circuit breaker is off and 122.5V when the wall switch is on.

So the question is what would cause there to be 36VAC when the wall switches are off?

Is this likely to be the source of failure of the old light fixture (I did try replacing the bulbs, but no luck)?

Miscellaneous:
The new light fixture I plan to install is an Artika Skylight ultra thin LED panel, FWIW. It allows for a dimmable controller, although that will come later if at all. However, I am concerned that 36V may be enough to run the light at a lower level (which would not be a big problem as it would probably make a good night light ... as long as it is safe)!
My house is ~16 years old.
Georgia - Atl. metro area has not invested in hiring more building inspectors as Atlanta has boomed over the past several decades, so don't assume things were done right during construction. If it worked initially, that is all a builder is worried about, the inspection is pretty much a "drive-by".
I have experienced this once before in an older house (50+ years with screw in fuses at the panel), but I did not worry about it after an electrician said it is not uncommon with older homes and if it was him, he would not mess with it. I was replacing overhead light with Ceiling Fan/Light.
As far as my own competence, I am a dude with a Black & Decker Complete Guide to Home Wiring book, but do not see a "Troubleshooting" section. I did successfully install a 240V sub-panel when I got a 240V Powermatic lathe, so I'm good pretty at following directions!

TIA!

Cheers,
Kurt

 

[-Jim-]

Kurt,

Is the fixture on a 3 or 4 way switch? I've read of installations where phantom voltages are available on the switch legs. Personally I've never run into it even though I am a certified Electrician (from ages ago).

"What causes ghost voltage?

Ghost voltages can be caused when energized circuits and non energized wiring are located in close proximity to each other, such as in the same conduit or raceway. This condition forms a capacitor and allows capacitive coupling between the energized wiring and the adjacent unused wiring"

 

[Verdinut]

Kurt,

Is the fixture on a 3 or 4 way switch? I've read of installations where phantom voltages are available on the switch legs. Personally I've never run into it even though I am a certified Electrician (from ages ago).

"What causes ghost voltage?

Ghost voltages can be caused when energized circuits and non energized wiring are located in close proximity to each other, such as in the same conduit or raceway. This condition forms a capacitor and allows capacitive coupling between the energized wiring and the adjacent unused wiring"

I'm encountering the same situation as Kurt in my apartment. I read a voltage of 30 volts today on the top section of a duplex outlet when the switch is off. However, I remember having read 42 volts about 20 years ago on same outlet.
I found that really weird but I never mentioned it to the janitor, as I figured there wasn't any serious risk with this situation.

 

[TLS Guy]

Hey guys, I am replacing a fluorescent overhead kitchen light that quit working.
I assume the ballast went out, but I was kind of looking for an excuse to replace it anyway.

When I apply a multimeter, I get ~36VAC when both of the wall switches are off!
I do get 0V when the circuit breaker is off and 122.5V when the wall switch is on.

So the question is what would cause there to be 36VAC when the wall switches are off?

Is this likely to be the source of failure of the old light fixture (I did try replacing the bulbs, but no luck)?

Miscellaneous:
The new light fixture I plan to install is an Artika Skylight ultra thin LED panel, FWIW. It allows for a dimmable controller, although that will come later if at all. However, I am concerned that 36V may be enough to run the light at a lower level (which would not be a big problem as it would probably make a good night light ... as long as it is safe)!
My house is ~16 years old.
Georgia - Atl. metro area has not invested in hiring more building inspectors as Atlanta has boomed over the past several decades, so don't assume things were done right during construction. If it worked initially, that is all a builder is worried about, the inspection is pretty much a "drive-by".
I have experienced this once before in an older house (50+ years with screw in fuses at the panel), but I did not worry about it after an electrician said it is not uncommon with older homes and if it was him, he would not mess with it. I was replacing overhead light with Ceiling Fan/Light.
As far as my own competence, I am a dude with a Black & Decker Complete Guide to Home Wiring book, but do not see a "Troubleshooting" section. I did successfully install a 240V sub-panel when I got a 240V Powermatic lathe, so I'm good pretty at following directions!

TIA!

Cheers,
Kurt

Was this voltage between live and neutral, or live and ground?

I ask this as I suspect your house is older, and has daisy chained neutrals, which is no longer allowed. In years past loads where largely continuous, which means they drew current throughout the AC cycle. Now loads are very much in the main discontinuous, such as LED lights and devices, plus switching power supplies and many others. This situation has created a circumstance known as neutral gouging, which can lead to serious problems. This is why daisy chained neutrals are now against the electrical codes.

So what I would like to know is what is the voltage between live and neutral with the switch off, and the voltage between neutral and ground with the switch on and off.

This is a major issue, that no one knows really what to do with. Ideally all homes with daisy chained neutrals, which I'm sure is by far and away the majority, should really be rewired top to bottom. However that is a major undertaking and expense, and means opening up a lot of walls. The politics of the situation has prevented that nettle being grasped.

 

[Verdinut]

Was this voltage between live and neutral, or live and ground?

I ask this as I suspect your house is older, and has daisy chained neutrals, which is no longer allowed. In years past loads where largely continuous, which means they drew current throughout the AC cycle. Now loads are very much in the main discontinuous, such as LED lights and devices, plus switching power supplies and many others. This situation has created a circumstance known as neutral gouging, which can lead to serious problems. This is why daisy chained neutrals are now against the electrical codes.

So what I would like to know is what is the voltage between live and neutral with the switch off, and the voltage between neutral and ground with the switch on and off.

This is a major issue, that no one knows really what to do with. Ideally all homes with daisy chained neutrals, which I'm sure is by far and away the majority, should really be rewired top to bottom. However that is a major undertaking and expense, and means opening up a lot of walls. The politics of the situation has prevented that nettle being grasped.

In my case, The voltage is between the live and the neutral outlet slots.

 

[Alex2507]

It's normal induced voltage from the 3-way business.
I asked a sparky about it when I first moved here and noticed.

I have faith in electrical inspections.

should really be rewired top to bottom.

I can fix the walls.

 

[TLS Guy]

In my case, The voltage is between the live and the neutral outlet slots.

So you have classic neutral gouging, not good. Your QSC amps must put that on steroids. Unfortunately the solution is rewiring the apartment complex.

 

[KEW]

Good to hear from you, Dr. Mark!

Was this voltage between live and neutral, or live and ground?
The 36-37V reading was between live and neutral.

I ask this as I suspect your house is older - my home is 16, maybe 17 years old - , and has daisy chained neutrals, which is no longer allowed. In years past loads where largely continuous, which means they drew current throughout the AC cycle. Now loads are very much in the main discontinuous, such as LED lights and devices, plus switching power supplies and many others. Does that mean my rogue wiring is not going to work with the LED light fixture I have? This situation has created a circumstance known as neutral gouging, which can lead to serious problems. This is why daisy chained neutrals are now against the electrical codes.

So what I would like to know is what is the voltage between:
1) live and neutral with the switch off
37.3V
2) the voltage between neutral and ground with the wall switch on and off.
On: 120.4V
Off: 37.8V

This is a major issue, that no one knows really what to do with. Ideally all homes with daisy chained neutrals, which I'm sure is by far and away the majority, should really be rewired top to bottom. However that is a major undertaking and expense, and means opening up a lot of walls. The politics of the situation has prevented that nettle being grasped.

 

[KEW]

Kurt,

Is the fixture on a 3 or 4 way switch?

Hey Jim!
There are 2 each 2-way switches for the light.

 

[KEW]

I'm encountering the same situation as Kurt in my apartment. I read a voltage of 30 volts today on the top section of a duplex outlet when the switch is off. However, I remember having read 42 volts about 20 years ago on same outlet.
I found that really weird but I never mentioned it to the janitor, as I figured there wasn't any serious risk with this situation.

Safety in numbers, right? If we all have this poop going on we're all safe, right? ... Right??

 

[ryanosaur]

(Good to see you back here, KEW! I hope you are doing well. Cheers!!!)

 

[KEW]

I have faith in electrical inspections.

It occurred to me that there might be some state (or county) that actually performed a proper inspection, but maybe I'm mixing up la-la-land with reality!

 

[KEW]

(Good to see you back here, KEW! I hope you are doing well. Cheers!!!)

Good to hear from lots of the old gang.
I am actually doing quite well for the most part.
Now that I have had time to heal/adapt from my subdural hematoma, I have realized that my verbal skills have been impacted.
My verbal skills were never great (and I always spoke relatively slowly, but not too much as to be an outlier here in the south).
The good news is that my cognitive skills have not been impacted (that I have noticed). I may be using the wrong words, because verbal skills probably are cognitive, but what I am saying is that thought-wise, I seem to be my old self, but when it comes time to write it down or speak, it can get frustrating. For instance, I probably spent an hour composing my first post in this thread to get all of the i's dotted and t's crossed.
I also run into problems giving commands on the fly, where Alexa does not have enough patience for me because of pregnant pauses in my speech. For example, if I have a command like "Alexa, play Ed Palermo Big Band from Pandora on the downstairs group" I might glitch and pause before "downstairs group" because I don't think in words the way many people do, and I know I want to play the music on "these" speakers so I can walk around without leaving the music behind. However, remembering that "downstairs group" is the proper "code word" for this group can just take too much time unless I mentally rehearse it before I actually say the command.
I need to see if Alexa has a way to increase it's "patience" for me. I am still quicker than some older people (like my grandma in her late 80's and early 90's) so I can imagine that Amazon may allow for such a disability.
But aside from Alexa and the added burden for writing out messages which is a serious penalty on a forum like this, it is pretty much "business as usual". I am still playing Bari Sax in the 3 Big Band Swing Bands and my music performance is on par with what it was before my accident, and that alone gives me a better quality of life than I ever thought I'd have in retirement (not that I was a pessimist, I just loved playing in stage band in HS and never expected to do it again, much less, 3 bands)!

 

[ryanosaur]

Good to hear from lots of the old gang.
I am actually doing quite well for the most part.
Now that I have had time to heal/adapt from my subdural hematoma, I have realized that my verbal skills have been impacted.
My verbal skills were never great (and I always spoke relatively slowly, but not too much as to be an outlier here in the south).
The good news is that my cognitive skills have not been impacted (that I have noticed). I may be using the wrong words, because verbal skills probably are cognitive, but what I am saying is that thought-wise, I seem to be my old self, but when it comes time to write it down or speak, it can get frustrating. For instance, I probably spent an hour composing my first post in this thread to get all of the i's dotted and t's crossed.
I also run into problems giving commands on the fly, where Alexa does not have enough patience for me because of pregnant pauses in my speech. For example, if I have a command like "Alexa, play Ed Palermo Big Band from Pandora on the downstairs group" I might glitch and pause before "downstairs group" because I don't think in words the way many people do, and I know I want to play the music on "these" speakers so I can walk around without leaving the music behind. However, remembering that "downstairs group" is the proper "code word" for this group can just take too much time unless I mentally rehearse it before I actually say the command.
I need to see if Alexa has a way to increase it's "patience" for me. I am still quicker than some older people (like my grandma in her late 80's and early 90's) so I can imagine that Amazon may allow for such a disability.
But aside from Alexa and the added burden for writing out messages which is a serious penalty on a forum like this, it is pretty much "business as usual". I am still playing Bari Sax in the 3 Big Band Swing Bands and my music performance is on par with what it was before my accident, and that alone gives me a better quality of life than I ever thought I'd have in retirement (not that I was a pessimist, I just loved playing in stage band in HS and never expected to do it again, much less, 3 bands)!

I remember that you mentioned some of that before... I'm glad to see you visiting and stoked you are still blowing!

 

[TLS Guy]

Good to hear from you, Dr. Mark!

So, you have some neutral gouging.

It is an issue. The first thing I would do is ask an electrician to have look at the bonding between neutral and ground at the panel. Make sure it is in good order and may be beef it up.

This is an issue. When I was at Benedict Lake, it seemed to me that if there was a strange occurrence the artisans would turn up at my door. Well one evening the panel at a house on the other side of the lake had smoked. On investigating the problem was at the neutral connection to ground at the panel. This was a case of neutral gouging with too much current on the neutrals. This has led to a bigger problem for the power companies and caused stray voltage issues, due to inadequate neutral capacity. So neutrals have had to be beefed up.

This is a concern in the home, and has been a documented cause of house fires. The breaker is in the live circuit and no breaker in neutral, so there is no detection for an overloaded and heating neutral. We are just lucky that most of the time these old daisy chained neutrals are not resulting in harm.

Your LED light will work just fine, but be cognoscente of how many discontinuous loads you add. The really big risk is inductive cook tops. However they now require they be wired right back to the panel. All other electric cook tops are continuous loads.

This is an issue, that I know is of concert to authorities and regulators, and I'm sure they are watching the situation. In the UK they have pretty much enforced rewiring. I think the day will some here were rewiring with separation of neutrals will end up having to be enforced.

When I remodeled our lake home in 2005/6 I did separate most of the neutrals. This was a big factor in me building a new home rather then remodeling and older home. Having zero daisy chained neutrals, and a really good whole house grounding plan is actually a prerequisite for a state of the art AV room or audio system. This is something we likely don't talk about enough.

 

[Verdinut]

This in information provided by Fluke Corporation:

When you place your multimeter leads between the open circuit and the neutral conductor, you effectively complete the circuit through the input of the multimeter. The capacitance between the connected, hot conductor and the floating conductor forms a voltage divider in conjunction with the multimeter input impedance. The multimeter then measures and displays the resulting voltage value.


Most digital multimeters today have an input impedance that’s high enough to show this ghost voltage, giving a false impression of a live conductor. The meter is actually measuring voltage coupled into the disconnected conductor. But at times, these voltages can be 80-85 % of what the “hard” voltage should be. If not recognized as a ghost voltage, additional time, effort and money may be lost troubleshooting circuit problems.

 

[KEW]

The breaker is in the live circuit and no breaker in neutral, so there is no detection for an overloaded and heating neutral.

Seems like a thermal scan across the surface of the panel would show if a severe problem exists!?
Or maybe take the panel cover off!?

 

[KEW]

This in information provided by Fluke Corporation:

When you place your multimeter leads between the open circuit and the neutral conductor, you effectively complete the circuit through the input of the multimeter. The capacitance between the connected, hot conductor and the floating conductor forms a voltage divider in conjunction with the multimeter input impedance. The multimeter then measures and displays the resulting voltage value.


Most digital multimeters today have an input impedance that’s high enough to show this ghost voltage, giving a false impression of a live conductor. The meter is actually measuring voltage coupled into the disconnected conductor. But at times, these voltages can be 80-85 % of what the “hard” voltage should be. If not recognized as a ghost voltage, additional time, effort and money may be lost troubleshooting circuit problems.

That makes sense, and is why I am thinking a thermal scan of the switch panel may be a way to determine that a fire is not in the works.
It seems like if there are no significant heat concentrations at the panel, there is not a serious safety hazard whether it is a ghost voltage or neutral gouging.
However, in matters of safety, I like to get confirmation from someone with experience before relying on my understanding of theory!

 

[-Jim-]

Hey Jim!
There are 2 each 2-way switches for the light.

When there are 2 switches for a (light) circuit it's called a 3 way and uses two 3 way switches. If there are 3 or more switches (yes, I've seen some but they are rare) it's called a 4 way and uses two 3 way switches and one (or more) 4 way switches.

No, I'm not making this up.

 

[-Jim-]

That makes sense, and is why I am thinking a thermal scan of the switch panel may be a way to determine that a fire is not in the works.
It seems like if there are no significant heat concentrations at the panel, there is not a serious safety hazard whether it is a ghost voltage or neutral gouging.
However, in matters of safety, I like to get confirmation from someone with experience before relying on my understanding of theory!

In a past life I was also a licensed Thermographer. The company I worked for would be hired to scan switch rooms at industrial complexes, Oil Refineries, Mine Sites, etc. as well as some sub-stations to check if the breakers, contactors, HV cable terminations, etc., were overheating which indicated either an overload (that should have been clear by the device) or high resistive contacts (typically only on a single phase of these 3 phase devices) that need servicing. I also serviced and rebuilt many Breakers and Contactors. Some were the size of a single car garage.

Sometimes Customers would also get us to scan their larger motors as we could easily detect overheated bearings without ever touching the machine. (Some motors had faulty, disconnected, or suspect BTDs - Bearing Temperature Devices.) Today you can get good imaging equipment for $1500 whereas our gear was well in excess of $20,000.

In a residential panel Thermal Imaging would be looking for a temperature differential typically where conductors are terminated due to a high resistance contact, and / or if a breaker is faulty and overheating. Both are somewhat rare. You could use a Infrared Digital Thermometer with Targeting Laser (cost about $30) which a lot of folks already have in their tool box (I do) if you wanted to look. I'd caution folks that this involves removing the cover off the panel typically while energized, and exposing live wires. You could turn off the main breaker, and then remove the cover, they reenergize the panel before scanning. That would be safer for those less confident in what they are doing.

Thermal Imaging won't give you any indication as to voltage levels on any conductor, and won't help you track down you phantom voltage source. Sorry.