Low voltage with breaker turned off

[cgrutt]

Ran into a strange problem replacing an outlet for my MIL. Kitchen outlet near sink she uses while ironing and it used to have a microwave plugged in. Refrigerator and another outlet is on same circuit. House was built around 1975. The outlet stopped working and was showing some visible damage from arcing so I replaced outlet.

When I pulled it out there was alot of damage to both outlet and wiring. Back of outlet had literally melted on the common side and a short pigtail that was connected was completely burned and broken off. There was some evidence of burning on wallpaper next to outlet under plate. The rest of the wiring looked fine.

I was disconnecting the wire nut attaching the common pigtail that was melted and felt a minor shock. Breaker and Refrigerator were off. I measured voltage and was getting approx. 19 VAC with Breaker off. 122VAC with Breaker on.

There was an unknown connection in box with a three wire black/red/white where one of the blacks was connected to red with a wire nut. There is a light fixture above sink that hasn't worked in years but the switch for it is on other side of the sink. Not sure if this is related or not didn't open up the other or light outlet yet to see if I could figure out what that wire was for. I'm assuming it is running up to light and back down to the outlet on other side of sink but haven't checked. In any case I don't think it has anything to do with the 19VAC.

So does anybody know why there is a small amount of voltage coming through with Breaker off? Could Breaker have been damaged when outlet shorted out and is leaking a small amount of voltage? And more importantly, could the stray voltage have anything to do with why the outlet shorted out? Don't want to risk a fire but the new outlet seems to be fine with Breaker on.

Sorry for long post figured I'd give as much info as I know. Thanks.

 

[TurnipTruck]

You have found some induced voltage. Just like a transformer, when an unpowered wire lays next to a powered wire, the constant build and collapse of the magnetic field in an alternating current circuit will induce a voltage in the unpowered wire. I have also noticed a small (bleed?) voltage when the circuit involves an illuminated switch.
Not a professional, tho.

 

[PCustoms]

^^^my first thought was induced/ghost voltage, but I'm pretty sure that shouldn't result in a shock

 

[LopezBart]

If you plug a lamp or other small load into the outlet and switch off the breaker, what voltage do you see? If it's truly an induced voltage, it should be zero. Modern DVMs have a very high input impedance, but any load on the circuit should drive the ghost voltage to zero. If there's still voltage present after adding a lamp, something else is going on.

 

[cgrutt]

Yeah I don't think it's phantom voltage because I got a small shock from it. The refrigerator is on same circuit and was plugged in. As was a coffee maker. The refrigerator is old I don't think there is anything there that could be backfeeding. The coffee maker has a small clock in it so some sort of circuit board. Maybe something with that but I doubt it. I'm thinking the circuit breaker is somehow allowing some voltage to bleed through but no clue how that would step down to 19v.

 

[PCustoms]

Yeah I don't think it's phantom voltage because I got a small shock from it. The refrigerator is on same circuit and was plugged in. As was a coffee maker. The refrigerator is old I don't think there is anything there that could be backfeeding. The coffee maker has a small clock in it so some sort of circuit board. Maybe something with that but I doubt it. I'm thinking the circuit breaker is somehow allowing some voltage to bleed through but no clue how that would step down to 19v.

These were off though, as the breaker was off, right?

 

[mm08822]

Trace the wire from the cb to where it exits the panel. Is it a 2 or 3 conductor cable?

If 3 conductor, then you may have created an open neutral condition on the other circuit. Turn off the the other cb.

If 2 conductor cable, check voltage at cb with cb off.

Also unplug cb leaving wire connected to it and read voltage on cb terminal to grd.

 

[ybnormal]

I've also got a similar situation. the dishwasher in kitchen has ALWAYS had a bleedover of about 7v, after flipping the breaker off. don't know why. switch has never been replaced to my knowledge in 40 yrs so maybe a bad switch? pretty sure it's not the breaker because the entire box was swapped out after the lightning strike and electrical damage 6 yrs go.

we're getting ready to start a kitchen remodel (original 40yr old kitchen) so I'll have that checked when we get to that point.

 

[BrandonV]

Yeah I don't think it's phantom voltage because I got a small shock from it. The refrigerator is on same circuit and was plugged in. As was a coffee maker. The refrigerator is old I don't think there is anything there that could be backfeeding. The coffee maker has a small clock in it so some sort of circuit board. Maybe something with that but I doubt it. I'm thinking the circuit breaker is somehow allowing some voltage to bleed through but no clue how that would step down to 19v.

Did you unplug the refrigerator and the clock? The first thing I would do after turning off the breaker is ensure all the known loads that typically exist on the circuit are physically disconnected if possible from the circuit. If the voltage is still there you can start to suspect the wiring or the breaker.

 

[wyliesdiesels]

Yeah I don't think it's phantom voltage because I got a small shock from it. The refrigerator is on same circuit and was plugged in. As was a coffee maker. The refrigerator is old I don't think there is anything there that could be backfeeding. The coffee maker has a small clock in it so some sort of circuit board. Maybe something with that but I doubt it. I'm thinking the circuit breaker is somehow allowing some voltage to bleed through but no clue how that would step down to 19v.

test for voltage at the breaker then.

also could be a 3-wire MWBC and youre getting back fed voltage from the other circuit.

 

[sparky 1971]

My guess is that it's a MWBC and the neutral is loaded by the other circuit. That's the reason for the relatively new code requirement for handle ties or common trip breakers for MWBC's.

 

[cgrutt]

Sorry what is a MWBC? I haven't pulled the front off box but it looks like a standard single slot breaker from front. As far as creating an open neutral all I did was replace the outlet the same way it was originally wired. It reads 19v with breaker off fully assembled the way it existed originally. Edit: it was probably 19v unassembled, it's currently reassembled and reading zero with breaker off. I haven't tried unplugging appliances yet but will do that. I'm changing plugs in my pickup at the moment so will get to it later. Thanks.

 

[cgrutt]

Breaker marked with red arrow

 

[bwringer]

Stuff like this started to fail in my house when it was about 25 years old, and after replacing two or three absolutely terrifying burned-up receptacles, I took a lazy afternoon and replaced every last switch and receptacle in the whole house. From all the overheated and burned stuff I found, it's an absolute wonder we didn't perish in an electrical fire.

Backstabbing is incredibly awful, lazy, stupid practice, and should never have been even slightly legal.

Not that this necessarily has anything to do with the OP's issue, other than the OP also got lucky and didn't burn the house down, and should pull all the faceplates and take a look at what's actually going on in there. I'd bet many more have heat and fire damage.

 

[cgrutt]

I'm painting rooms for her and actually replacing all the outlets and switches while I'm at it. Just did this one because it was burnt out.

I see there is a red wire going to breaker below it so I bet you guys were right about the MWBC (I googled it). That would also explain the red wire in box. I just switched the one breaker off and it's currently zero (0.2 VAC on my meter). The neutrals were probably loose when I got shocked and it was probably coming from breaker below it. Seems to be all good now. Thanks for the help! Learn something new everyday...

 

[cgrutt]

These were off though, as the breaker was off, right?

Yes, sorry, breaker off but appliances still plugged into circuit.

I think it's all sorted out now. Thanks.

 

[BrandonV]

I'm painting rooms for her and actually replacing all the outlets and switches while I'm at it. Just did this one because it was burnt out.

I see there is a red wire going to breaker below it so I bet you guys were right about the MWBC (I googled it). That would also explain the red wire in box. I just switched the one breaker off and it's currently zero (0.2 VAC on my meter). The neutrals were probably loose when I got shocked and it was probably coming from breaker below it. Seems to be all good now. Thanks for the help! Learn something new everyday...

Good opportunity to go thru the rest of the panel and install handle ties.

 

[cgrutt]

Just looking into this some more this diagram appears to be how the outlets were wired. The second phase A outlet is wired the same as what was in box right down to the short pigtail on the common and two hots (black) screwed to side of terminal. Wasn't aware of this before today thanks again.



So just to follow up on earlier question, would this wiring have contributed to the outlet burning out/melting or do you think it was just a coincidence? I'm guessing the screw connecting neutral pigtail was loose and it arced out but not sure. The new outlet is getting 122VAC with breaker on and 0.2VAC with breaker off so I think it's fine.

 

[BrandonV]

Just looking into this some more this diagram appears to be how the outlets were wired. The second phase A outlet is wired the same as what was in box right down to the short pigtail on the common and two hots (black) screwed to side of terminal. Wasn't aware of this before today thanks again.



So just to follow up on earlier question, would this wiring have contributed to the outlet burning out/melting or do you think it was just a coincidence? I'm guessing the screw connecting neutral pigtail was loose and it arced out but not sure. The new outlet is getting 122VAC with breaker on and 0.2VAC with breaker off so I think it's fine.

MWBC is a safe configuration when installed correctly. If the only integrity issue was with the loose neutral at the receptacle screw itself (assuming the rest of the neutrals were securely connected together in the box with a pigtail) you should be fine.

 

[cgrutt]

MWBC is a safe configuration when installed correctly. If the only integrity issue was with the loose neutral at the receptacle screw itself (assuming the rest of the neutrals were securely connected together in the box with a pigtail) you should be fine.

Thanks. Yes the neutrals were all together and tight. The short pigtail to outlet was burned up.

 

[sparky 1971]

So just to follow up on earlier question, would this wiring have contributed to the outlet burning out/melting or do you think it was just a coincidence? I'm guessing the screw connecting neutral pigtail was loose and it arced out but not sure. The new outlet is getting 122VAC with breaker on and 0.2VAC with breaker off so I think it's fine.

It's more than likely that you had a cheap budget grade receptacle that had lived it's useful life. The screw may not have been properly tightened or it could have worn out from the inside out due to the load from the microwave and having the iron plugged in and unplugged repeatedly over the years, it happens. Eventually everything wears out.

 

[cgrutt]

It's more than likely that you had a cheap budget grade receptacle that had lived it's useful life. The screw may not have been properly tightened or it could have worn out from the inside out due to the load from the microwave and having the iron plugged in and unplugged repeatedly over the years, it happens. Eventually everything wears out.

Thanks. Yeah I would have been fine with it but the 19v thing had me second guessing everything. Appreciate all of your help.

 

[sparky 1971]

Breaker marked with red arrow

I can't believe nobody has jumped in yet to complain about the Homeline and BR breakers installed in what I believe is a Siemens or ITE panel. (personally, I don't care, I may be guilty of installing a BR breaker or 30 in Siemens panels during the Covid supply chain issues) And that single pole 30? I hope it goes to a camper, I don't know of anything else that's a 30 amp 120 volt in a residential setting.

 

[cgrutt]

I can't believe nobody has jumped in yet to complain about the Homeline and BR breakers installed in what I believe is a Siemens or ITE panel. (personally, I don't care, I may be guilty of installing a BR breaker or 30 in Siemens panels during the Covid supply chain issues) And that single pole 30? I hope it goes to a camper, I don't know of anything else that's a 30 amp 120 volt in a residential setting.

No clue but it's been that way for a long time. My FIL passed seven years ago the room that panel is in used to be a garage and was finished off probably 15 years ago that's last time it would have been touched. They have a generator installed don't know how that plays into any of this. My FIL was heavily involved with VFW and KOC and had alot of "friends" do work for him so not surprised. Is what it is.

 

[sparky 1971]

No clue but it's been that way for a long time. My FIL passed seven years ago the room that panel is in used to be a garage and was finished off probably 15 years ago that's last time it would have been touched. They have a generator installed don't know how that plays into any of this. My FIL was heavily involved with VFW and KOC and had alot of "friends" do work for him so not surprised. Is what it is.

Back when it was a garage there was probably a problem with a breaker constantly tripping whenever a table/miter saw was used. I've seen a whole lot worse, including nails used where fuses were supposed to go.

 

[cgrutt]

Back when it was a garage there was probably a problem with a breaker constantly tripping whenever a table/miter saw was used. I've seen a whole lot worse, including nails used where fuses were supposed to go.

He added a 2 -1/2 car garage to end of house and had a lot of old power equipment bench grinders, band saws, scroll saws, sanders, etc so probably goes to new garage. It's funny he also owned a camper so probably used what he had on hand. It might have come from camper. IDK.

 

[sparky 1971]

He added a 2 -1/2 car garage to end of house and had a lot of old power equipment bench grinders, band saws, scroll saws, sanders, etc so probably goes to new garage. It's funny he also owned a camper so probably used what he had on hand. It might have come from camper. IDK.

I doubt anything bad will happen because of it, but if you ever decide to sell you probably should get the right size and brand in there. Or leave it so the inspector can find something to show the potential buyers that they didn't waste their money by hiring him. Then fix it and everyone will be happy. I just couldn't believe the thread didn't derail over it before the actual topic was covered.

 

[Jim greengo]

Ran into a strange problem replacing an outlet for my MIL. Kitchen outlet near sink she uses while ironing and it used to have a microwave plugged in. Refrigerator and another outlet is on same circuit. House was built around 1975. The outlet stopped working and was showing some visible damage from arcing so I replaced outlet.

When I pulled it out there was alot of damage to both outlet and wiring. Back of outlet had literally melted on the common side and a short pigtail that was connected was completely burned and broken off. There was some evidence of burning on wallpaper next to outlet under plate. The rest of the wiring looked fine.

I was disconnecting the wire nut attaching the common pigtail that was melted and felt a minor shock. Breaker and Refrigerator were off. I measured voltage and was getting approx. 19 VAC with Breaker off. 122VAC with Breaker on.

There was an unknown connection in box with a three wire black/red/white where one of the blacks was connected to red with a wire nut. There is a light fixture above sink that hasn't worked in years but the switch for it is on other side of the sink. Not sure if this is related or not didn't open up the other or light outlet yet to see if I could figure out what that wire was for. I'm assuming it is running up to light and back down to the outlet on other side of sink but haven't checked. In any case I don't think it has anything to do with the 19VAC.

So does anybody know why there is a small amount of voltage coming through with Breaker off? Could Breaker have been damaged when outlet shorted out and is leaking a small amount of voltage? And more importantly, could the stray voltage have anything to do with why the outlet shorted out? Don't want to risk a fire but the new outlet seems to be fine with Breaker on.

Sorry for long post figured I'd give as much info as I know. Thanks.

Mwbc/shared neutral.

 

[dave*99]

That deadfront ( the cover with the openings for the breakers) does not seem to fit the breakers. As others have noted, they could be the wrong breakers - or the wrong cover too.

Now that you identified a MWBC, be sure it is a proper MWBC. The 2 breakers that feed that specific cable must be on opposite legs of the panel. That's why they must be located right next to each other. Be sure that is the case. And add a handle tie.

 

[dave*99]

When I pulled it out there was alot of damage to both outlet and wiring. Back of outlet had literally melted on the common side and a short pigtail that was connected was completely burned and broken off. There was some evidence of burning on wallpaper next to outlet under plate. The rest of the wiring looked fine.

Re-reading this plus we know it's a MWBC......
I suspect your 2 breakers feeding this circuit are on the same leg of the service panel.

When this happens, you get double the current on the neutral conductor.
If you have (2) 20A breakers feeding the circuit and the breakers are NOT ON OPPOSITE LEGS, you can get 40A on the neutral and things like your receptacle and wires melt.

In a properly wired MWBC, the neutral carries the difference current. A 20A load applied to BOTH LEGS results in zero amps on the neutral.

Check those breakers!

 

[PCustoms]

Re-reading this plus we know it's a MWBC......
I suspect your 2 breakers feeding this circuit are on the same leg of the service panel.

When this happens, you get double the current on the neutral conductor.
If you have (2) 20A breakers feeding the circuit and the breakers are NOT ON OPPOSITE LEGS, you can get 40A on the neutral and things like your receptacle and wires melt.

In a properly wired MWBC, the neutral carries the difference current. A 20A load applied to BOTH LEGS results in zero amps on the neutral.

Check those breakers!

Well this is blowing my mind

 

[sparky 1971]

Re-reading this plus we know it's a MWBC......
I suspect your 2 breakers feeding this circuit are on the same leg of the service panel.

When this happens, you get double the current on the neutral conductor.
If you have (2) 20A breakers feeding the circuit and the breakers are NOT ON OPPOSITE LEGS, you can get 40A on the neutral and things like your receptacle and wires melt.

In a properly wired MWBC, the neutral carries the difference current. A 20A load applied to BOTH LEGS results in zero amps on the neutral.

Check those breakers!

It was only the pigtail for the neutral that was burned up (post #20), all it will see is the current from that device, not the combined load. While it's possible that both circuits are on the same phase, that didn't cause this problem.

 

[cgrutt]

Re-reading this plus we know it's a MWBC......
I suspect your 2 breakers feeding this circuit are on the same leg of the service panel.

When this happens, you get double the current on the neutral conductor.
If you have (2) 20A breakers feeding the circuit and the breakers are NOT ON OPPOSITE LEGS, you can get 40A on the neutral and things like your receptacle and wires melt.

In a properly wired MWBC, the neutral carries the difference current. A 20A load applied to BOTH LEGS results in zero amps on the neutral.

Check those breakers!

Thanks ill track it down but suspect the breaker with the red wire below it is the 2nd circuit which would put it on alternate phase.

 

[Fav Onefour]

Thanks. Yes the neutrals were all together and tight. The short pigtail to outlet was burned up.

Did they use lighter wire on the pigtails?
Based on the description, it sounds like the outlet was loaded on a loaded circuit.

It's not terribly surprising that you found some damage in the box. I generally replace the receptacles and switches on each new place. There have been numerous occasions that left me amazed the place was still standing.
I'm sure that a lot of the damage is a result of the Griswold approach.
Some people will do incredible stunts to make an outlet work. Had an office gal running two space heaters and her old big dog PC on a clackety power strip. She duct taped the strip plug to one side because it was "sparking" when the heaters kicked on. I found out about her electrician status when the I.T. guy came to me. Apparently, arcing and brownouts were hard on those old computers.
Ironically, the company had a policy of NO power strips. I guess they had problems with little stuff like fires at other locations.

 

[chinboys]

I would turn off the whole house's main breaker and check if you still see these voltages at that box.
If you don't, turn on one breaker at a time until you see these voltages again.
Per historical and present-day AC voltage design... current flows or is being pushed by voltage and these electrons want to make a complete circuit or return to the generating station at 60 cycles/second. The current will flow in less resistance lines or things (you, other metal conductors, and earth ground)
You might find another circuit breaker's circuit neutral tied to this existing circuit that shows these low voltages even though its circuit breaker is off.

 

[PCustoms]

I love it, the issue is solved and all the Internet EE come out to respond.

 

[sparky 1971]

Did they use lighter wire on the pigtails?
Based on the description, it sounds like the outlet was loaded on a loaded circuit.

It's a 20 amp circuit so I am going to assume it has 12 gauge wire run to it. Even if for some reason #14 was used for a pigtail, it's not going to melt down. Just because the code book has an * that takes you to a spot that says 14 is limited to a 15 amp breaker (in most, but not all, cases), it's going to take more than 20 amps to get it to heat up to a point of failure. This is probably a worn out device. Whether it was the screw on the side or the internal contacts that failed is up for debate and nobody is ever going to know the answer to that. It could also have been a **** connection at the pigtail joint with the "line and load" connections being ok and the short pigtail barely being connected, but I doubt it if it's as old as I think it is.

 

[sparky 1971]

I would turn off the whole house's main breaker and check if you still see these voltages at that box.
If you don't, turn on one breaker at a time until you see these voltages again.
Per historical and present-day AC voltage design... current flows or is being pushed by voltage and these electrons want to make a complete circuit or return to the generating station at 60 cycles/second. The current will flow in less resistance lines or things (you, other metal conductors, and earth ground)
You might find another circuit breaker's circuit neutral tied to this existing circuit that shows these low voltages even though its circuit breaker is off.

Unelss it's an emergency, never, ever, ever, turn off a main in an old house unless it has been cycled on and off intentionally over the years. There's a real good chance that if it gets turned off it ain't gonna turn back on. I've seen it many times, some of those mains are no longer available which means it's time for a new panel.

The problem that the OP had has been taken care of, it is no longer an issue.

 

[cgrutt]

Yeah there's no voltage (0.2vac per my meter) on circuit with the breaker off the stray voltage was happening while it was apart. I wasn't aware of the MWBC issue until the good folks here suggested it. It's all good. The outlet was almost 50 years old I think the pigtail may have been loose or the outlet just wore out. It's all good thanks again for all the comments.

 

[sparky 1971]

I love it, the issue is solved and all the Internet EE come out to respond.

Would you expect anything less or have it any other way? This is Garage Journal, where it becomes a contest to make even the most menial task something more difficult than moving a mountain with a teaspoon.