So I have a 12/3 homerun into my kitchen (plug behind the fridge) black is garbage disposal dishwasher and red is the rest of the plugs in kitchen (house was built in 1960s) .. when I shut off kitchen plug circuit I still have low voltage running thru the garbage disposal dishwasher circuit .. is it just the shared neutral that is carrying a small amount of current when one circuit is off??? Do I have a problem.. my fiance got a bug up her ass and now wants to look at the electrical.. this has been this way since she bought the house 13 years ago .. please any answers help
12/3 homerun into kitchen sharing neutral
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That is a "Multi-Wire Branch Circuit" or MWBC.
Your setup is grandfathered, but you should update it nonetheless. The two circuit breakers in an MWBC must be a 240V 2-pole breaker. Alternately it's allowed to use 2 breakers with a factory handle-tie, but those 2 breakers must occupy the same panel space as a 240V 2-pole breaker, because it needs access to 2 adjacent spaces so it can get both poles. MWBCs must be on opposite poles (must have 240V between them) otherwise they will overload the neutral.
The purpose of the 2-pole/handle-tie is to assure that when you turn off 1/2 of the circuit for maintenance, you are also turning off the other 1/2.
Otherwise you're asking to get nailed.
But yes, current is moving through the shared part of the circuit! Don't separate the neutrals without doing the above.
If you hate MWBCs / don't want to deal with them, I totally understand. Pull two 12/2 cables to replace the 12/3, and land them on the breakers normally. I have been retiring MWBCs on-sight on my Pushmatic panels, because I can't get handle-ties for the breakers, and *new-stock* Pushmatic breakers have Zinsco disease, because somehow, 康涅狄格州 Electric managed to screw them up.
Your setup is grandfathered, but you should update it nonetheless. The two circuit breakers in an MWBC must be a 240V 2-pole breaker. Alternately it's allowed to use 2 breakers with a factory handle-tie, but those 2 breakers must occupy the same panel space as a 240V 2-pole breaker, because it needs access to 2 adjacent spaces so it can get both poles. MWBCs must be on opposite poles (must have 240V between them) otherwise they will overload the neutral.
The purpose of the 2-pole/handle-tie is to assure that when you turn off 1/2 of the circuit for maintenance, you are also turning off the other 1/2.
Otherwise you're asking to get nailed.
But yes, current is moving through the shared part of the circuit! Don't separate the neutrals without doing the above.
If you hate MWBCs / don't want to deal with them, I totally understand. Pull two 12/2 cables to replace the 12/3, and land them on the breakers normally. I have been retiring MWBCs on-sight on my Pushmatic panels, because I can't get handle-ties for the breakers, and *new-stock* Pushmatic breakers have Zinsco disease, because somehow, 康涅狄格州 Electric managed to screw them up.
Ok with that being said let me just tell you what is going on exactly .. my fiance has been going around checking all the electrical and noticed that when she would shut off the garbage disposal dishwasher breaker that she would still get her tick tracer to beep (2 bars instead of the full six) so asked me to look I took apart the box identified where power was coming in checked it with my meter when breaker was on I got 118 and checked with the breaker off and was getting around 27 volts on the hot leg (not neutral) and this is with all of the wires separated in that box but the neutrals where the homerun lands were still all tired together .. this is normal with multibranch circuit? Is what ur saying in previous post .. (I'm sorry I hope that makes sense)
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Tick tracers work on induced current, so it could be reading an adjacent wire, or one close by. I think another problem you will have is with GFCI receptacles sharing a neutral. Once a circuit experiences a ground fault, any GFCI on the circuit could stand the chance of tripping due to the imbalance in the wiring. Like @seharper says, I'd replace any MWBC going to the kitchen with separate 12-2 cables and separate breakers.
And the 57 volts you are experiencing is "phantom voltage".
And the 57 volts you are experiencing is "phantom voltage".
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It's phantom voltage, so not a need to worry about it. It's a common thing when using digital voltmeters.
Ground fault circuit interrupter duplex receptacles should not give you any trouble if you leave the load terminals empty (and the yellow tape if any still covering them).
You can create a subcircuit with 12-2 cable coming off the GFCI receptacle load terminals going off in another direction to another, ordinary, receptacle which will receive GFCI protection.
You may not connect any of the three wires of a MWBC to the load terminals of a GFCI receptacle.
You can daisy chain a MWBC through GFCI receptacles using their line terminals only, for example black and white for receptacle #1, red and white for receptacle #2, black and white for #3, and so on.
If you plug in a lamp fixture with an incandescent lamp bulb and switch that on then the 57 volts phantom voltage should drop to zero. If the voltage does not drop to zero and perhaps the bulb glows a little than it is not phantom voltage and something is wrong.
You can create a subcircuit with 12-2 cable coming off the GFCI receptacle load terminals going off in another direction to another, ordinary, receptacle which will receive GFCI protection.
You may not connect any of the three wires of a MWBC to the load terminals of a GFCI receptacle.
You can daisy chain a MWBC through GFCI receptacles using their line terminals only, for example black and white for receptacle #1, red and white for receptacle #2, black and white for #3, and so on.
If you plug in a lamp fixture with an incandescent lamp bulb and switch that on then the 57 volts phantom voltage should drop to zero. If the voltage does not drop to zero and perhaps the bulb glows a little than it is not phantom voltage and something is wrong.
You have identified two sub-circuits that make up this MWBC. They need to have a tied handle-throw so they shut off together.
Phantom voltage comes from a disconnected wire running parallel to a hot wire for a long distance. Guess what! The two hots of an MWBC are in the same cable, so they run together for a long distance!
Your wife is seeing phantom voltage because she is turning off *one-half* of the MWBC, because she is able to turn off one-half of the MWBC. She should not be able.
Go get a proper handle-tie, or a 2-pole breaker that's correct for your panel, and make her un able
This also has the side effect of complying with code lol.
While you're in there, identify any other MWBCs, and do the same thing
Phantom voltage comes from a disconnected wire running parallel to a hot wire for a long distance. Guess what! The two hots of an MWBC are in the same cable, so they run together for a long distance!
Your wife is seeing phantom voltage because she is turning off *one-half* of the MWBC, because she is able to turn off one-half of the MWBC. She should not be able.
Go get a proper handle-tie, or a 2-pole breaker that's correct for your panel, and make her un able
This also has the side effect of complying with code lol.
While you're in there, identify any other MWBCs, and do the same thing
What do you mean by "phantom voltage is caused by DISCONNECTED wire that travels along etc" .. the two circuits running inside the same cable are both working circuits and are definently connected .. well were until now I plan on running two 12/2 home runs in the morning but I will have to junction one of the circuits in the attic because I really dont want to cut open anymore drywall (this isnt the first project shes had me do lol) unless somebody can tell me a good reason not too ? I'd really appreciate it thank u
Phantom voltage would not be caused by a disconnected wire but might be observed in a disconnected wire traveling alongside an energized wire for a significant distance.
The present NEC code requires two 20 amp circuits serving just receptacles in the kitchen, dining room, and/or pantry and intended for "small" appliances such as waffle iron or cake mixer. One half of the existing multiwire branch circuit may have qualified as one of the two required circuits but it does not hurt to install two new 20 amp circuits. Serving a hard wired fan or light or dishwasher would disqualify a branch circuit for this purpose.
The present NEC code requires two 20 amp circuits serving just receptacles in the kitchen, dining room, and/or pantry and intended for "small" appliances such as waffle iron or cake mixer. One half of the existing multiwire branch circuit may have qualified as one of the two required circuits but it does not hurt to install two new 20 amp circuits. Serving a hard wired fan or light or dishwasher would disqualify a branch circuit for this purpose.
Still using the word disconnected wire though .. what do you mean by that .. I belive it's old insulation and from what I've read the current can be passing thru even if the insulation is not broken .. it's old 12/3 romex from 1960 so I belive the insulation is old and current is passing thru circuits and that's where I'm getting the phantom voltage and to make the owner of the house happy I was planning on running the two new 20 amp circuits with a junction box in the attic for one of the circuits because it is on the exterior wall with the eve so isnt accessible without cutting the ceiling and probably wall open but I planned on using the old 12/2 jumper (which I'd junction in attic the other circuit I can drop down the wall it is behind the fridge)
By disconnected wire, he means a wire that is not connected to the AC mains (e.g. the circuit breaker is off).
Your house is full of electric fields from all the other circuits that have their breakers on. Digital multimeters tend to have high impedance inputs. That means they put a very, very small load on whatever it is that is being measured. The wires that are not powered can pick up the electric field from the other circuits, and that can result in a phantom voltage. A digital meter is so sensitive that it can measure it. The voltage is there, but it is very, very weak in terms of the current, which is so small it can't hurt you.
A way to confirm that this is a phantom voltage is to plug a lamp into the circuit. Leave the breaker off, but turn the lamp switch so it would be on. Then measure the voltage. If it's a phantom voltage, it should read zero.
When you unplug or turn off all the loads, you disconnect it on the LOAD side.
When you turn off the breaker, you disconnect it on the LINE side.
Now there is nothing making it be a particular voltage. It is "no voltage". It is just floating in the wind. And then the electric fields from the other nearby hot wire start influencing it, almost like picking up a radio broadcast... and putting this phantom voltage on it, which very sensitive testers can pick up.
Ever build a crystal radio out of wire wound around a toilet paper roll? It's entirely passive, it can pick up AM stations and make sound out a sensitive earpiece, entirely from the radiated power of the AM transmitter. You wouldn't believe it until you build one, and I bet every young boy in the 1960s and 1970s did... That's what's happening on the wire, but the radio station is a lot closer...
Omg!! Alright guys now she is telling me that she thinks the copper line for our fridge water is "charged" I've been an apprentice for a year and my boss decided to give me a shot running my own jobs before I got my card.. I've ran commercial/resi/subdivisions. I have basic knowledge of this old construction stuff .. new construction is easy ! Lol I take classes .. I read these forums.. I watch YouTube.. I'll never act like I know more than the next guy cuz I dont! .. I'm currently breaking my stuff out to look at this ridiculous accusation of the copper being "charged" is the word shes using (we've broken up I just live here at the moment) .. shes been tearing the whole house apart she claims she is itchy/staticky when she is home .. I've never felt this .. our roommates have never felt this nor has his kids .. is there anybody out there that may know anything about why shed feel that way (I think theres just something wrong with her but I was in love with her at one point so need to cover everything to ease her mind)
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