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Old 02-24-2009, 10:38 PM   #16
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Confused wiring


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You said you had BX cable (black and white) where did the "reds" come from?
Hi Bocolo - The alternate R-W wires at the service panel are combined with one white and start life as 3-wire BX cables. I'm assuming that these end in boxes where they get connected to BW-cables - the red to a black (for one circuit) and the black to another black (for the second circuit). This would mean that the neutral is shared on the "final home run". I admit I have not checked if 1 and 2 happen to be shared in this way. (it's messy, and as you warned, I'm not taking the service panel lightly).

Gary - yes, I should look into that. As if I were not confusing enough...

Cheers
Tyro

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Old 02-24-2009, 10:57 PM   #17
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Confused wiring


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Originally Posted by Tyro View Post
Hi Bocolo - The alternate R-W wires at the service panel are combined with one white and start life as 3-wire BX cables. I'm assuming that these end in boxes where they get connected to BW-cables - the red to a black (for one circuit) and the black to another black (for the second circuit). This would mean that the neutral is shared on the "final home run". I admit I have not checked if 1 and 2 happen to be shared in this way. (it's messy, and as you warned, I'm not taking the service panel lightly).

Gary - yes, I should look into that. As if I were not confusing enough...

Cheers
Tyro
These are likely multi wire branch circuits. The neutral is shared between both circuits. So the neutral isn't really dead until both are turned off.

Can you take a photo of your panel?

So with the A - B circuit thing, your saying B circuit does not work without A circuit being on, but with A on B works and with A off but B on B doesn't work??

Jamie
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Old 02-24-2009, 11:02 PM   #18
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Confused wiring


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You said you had BX cable (black and white) where did the "reds" come from?
Just checked, I have 19 breakers and 11 neutrals at the service panel. 3 of the whites and blacks leave in simple B+W BX, and the other 8 neutrals leave with 1 red+1black. Interestingly, I also have one VERY large (estimate much more than 10AWG) single white (neutral, it's wired to the bus) leaving on it's own, inside its own BX. It is also wired to the service panel itself.

I'll do some more checking on a day I'm less tired and can pull the main breaker. BTW, visually tracing the BX further than the ceiling of the garage is impossible.

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Tyro
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Old 02-24-2009, 11:20 PM   #19
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These are likely multi wire branch circuits. The neutral is shared between both circuits. So the neutral isn't really dead until both are turned off.
Good point, I think you're onto something?

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Originally Posted by jamiedolan View Post
Can you take a photo of your panel?
I'll look into it, but it will take a while till I can get a digital camera.

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Originally Posted by jamiedolan View Post
So with the A - B circuit thing, your saying B circuit does not work without A circuit being on, but ...
Yes

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..., but with A on B works ...
Provided circuit B is on also. If not (circuit A on and circuit B off), room B does not work

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...and with A off but B on B doesn't work??
Yes. Thus, if circuit A=1 in OP, and circuit B=2 in OP
  • A=on, B=on -> RoomA=powered, RoomB=powered
  • A=on, B=off -> RoomA=powered, RoomB=not powered, but 20V ghost **
  • A=off, B=on -> RoomA=no power, RoomB=no power, not even ghost
  • A=off, B=off -> RoomA=not powered, RoomB=not powered, not even ghost
(** "ghost" meaning specifically that there is 0V across a plain 400Ohm resistor wired from the incoming black to any white or ground, but 20V when I use the high impedance voltmeter directly)

Cheers
Tyro

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Old 02-24-2009, 11:35 PM   #20
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Confused wiring


I would agree wit the re-wire. From what I understand, my guess is there is an open neutral somewhere and these two rooms are fed from a MWBC (Multi Wire Branch Circuit). I am sure you will find a red and a black wire attached to the two breakers respectively that enter the same bundle of cable in the panel. When both circuits are on you are actually creating a 240 volt series circuit, which if its perfectly balanced it largely wouldnt be a problem, but this is a dangerous configuration in your case. Adding appliances to either side would most certaintly escalate the problem and make it worse.

Replace the wiring, do it right!
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Old 02-24-2009, 11:35 PM   #21
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Yes. Thus, if circuit A=1 in OP, and circuit B=2 in OP
  • A=on B=on RoomA=powered RoomB=powered
  • A=on B=off RoomA=powered RoomB=not powered, but 20V ghost
  • A=off B=on RoomA=no power RoomB=no power, not even ghost
  • A=off B=off RoomA=not powered RoomB=not powered, not even ghost

Cheers
Tyro
Good description of what is happening.

Are these regular breakers or are they tandems?

Jamie
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Old 02-25-2009, 05:54 AM   #22
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Confused wiring


It sounds like part of the wiring was updated with multi wire armored cable and connected somewhere along with the regular old BX (you said only 1 black, 1 white) no ground correct? Out of your four scenarios there is only one that does not work. My question is why did everything work before? Or did it? Maybe you just noticed now while troubleshooting? Did you nail anything or put screws in your walls? Don't mind me I don't know what I am talking about. I will shut up now and let Jamie take over, he has far more experience than I do. It's been interesting. Thanks.
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Old 02-25-2009, 07:13 AM   #23
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Confused wiring


If you do consider rewiring, you need to be sure you dont have a rodent problem...they love that romex insulation.

I do think this may be a multi wire branch circuit issue. Plug an extension cord from room b, run it to room a , and measure room a hot, to room b hot. If you get 240, you got a multi wire branch circuit, than measure from room b hot to room a neutral. Then try room a hot to room b neutral. Post your results.
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Old 02-25-2009, 02:17 PM   #24
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Turn off all the other breakers in the panel and turn on only a and b. Measure voltage between the hots.
Sounds to me like you still have a cross connecton between the two circuits. You must make this split at the panel or at the first junction box where the red and blacks are split.
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Old 03-01-2009, 03:20 PM   #25
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Hi - sorry to all those with assistance for being offline so long.

I did as rgsgww/joed/jamie suggested and measured voltages all over: turns out I have only 0V between ANY two hots, and 120V between any hot and gnd/neutral. Looks like I have only one leg of the single phase supply coming into the house - the voltage between the incoming (at the panel, upstream from the main breaker) black and red is ZERO. I'm assuming it should be 240V (Of course, each individual feed is 120V with respect to the neutral bus).

This would be a problem if I ever needed 240V, and surely a potential hazard since the MWBCs I have share neutrals on the home run? (it could potentially carry up to 30A on two 15A circuits, for example).

I called ConEd and they're coming out (I hope). About a year ago, someone rammed the utility pole in front of our house and ConEd has since replaced it. I'm guessing they accidentally rewired us with both legs from the "same side of the transformer."

Until this is repaired/looked into, I'm holding off any more "detective work"

Cheers
Tyro

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Old 03-01-2009, 06:16 PM   #26
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Hi -

I just got off the phone with ConEd, who basically told me I'm not automatically entitled to both legs. So, I have 120V between either incoming cable and ground, and 0V between the two incoming lines. If I want 240V between the two incoming, I have to apply for an "upgrade," presumably with hefty fees.

(1) Does anyone know if this could be true? Isn't it standard to get both legs? What's the point of two incoming lines if they deliver the same phase?
(2) Currently, I can live with 120 only. However, given that I have MWBC shared-neutrals on home runs, is this a "really dangerous" fire hazard, or "just" a "not so ideal situation?" If the two hots in a 14x3 are running near the full 15A, the neutral will have 30A (not approx 0A, as in two-legged wiring). I'm worried the neutral will fry...

Appreciate the help,
Cheers
Tyro
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Old 03-01-2009, 06:42 PM   #27
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Quote:
Originally Posted by Tyro View Post
Hi -

I just got off the phone with ConEd, who basically told me I'm not automatically entitled to both legs. So, I have 120V between either incoming cable and ground, and 0V between the two incoming lines. If I want 240V between the two incoming, I have to apply for an "upgrade," presumably with hefty fees.

(1) Does anyone know if this could be true? Isn't it standard to get both legs? What's the point of two incoming lines if they deliver the same phase?
(2) Currently, I can live with 120 only. However, given that I have MWBC shared-neutrals on home runs, is this a "really dangerous" fire hazard, or "just" a "not so ideal situation?" If the two hots in a 14x3 are running near the full 15A, the neutral will have 30A (not approx 0A, as in two-legged wiring). I'm worried the neutral will fry...

Appreciate the help,
Cheers
Tyro
Eh ??????

What size the main fuse/breaker you got there and senice I was reading this I just want to make sure I get details right .,,

Was this house wired in 1970's ? if so you should have a legit 60 amp 120/240 volt service minum size { 100 amp is common for that era }

The only time I did see 120 v 30 amp service is on older home or apartment complex otherwise it pretty much history nowdays.

In fact instering twist in Europe where I have extended stay there now { my second home } the min service size is 63 amp single phase or 32 amp tri phase most useally try to snag in 63 amp or larger both single and three phase service { yeah we have 240 v single phase and 415 v three phase service }

IMO I feel the POCO make a monster Conneries* with the hook up and look at the meter face see what it say it should say 240 volts if so you need to get this situation straghten out if you have old school round meter socket that will be pretty much history now.

Merci,Marc

* French word for bull****
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Old 03-01-2009, 06:56 PM   #28
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Eh ??????

What size the main fuse/breaker you got there and senice I was reading this I just want to make sure I get details right .,,

Was this house wired in 1970's ? if so you should have a legit 60 amp 120/240 volt service minum size { 100 amp is common for that era }

The only time I did see 120 v 30 amp service is on older home or apartment complex otherwise it pretty much history nowdays.

In fact instering twist in Europe where I have extended stay there now { my second home } the min service size is 63 amp single phase or 32 amp tri phase most useally try to snag in 63 amp or larger both single and three phase service { yeah we have 240 v single phase and 415 v three phase service }

IMO I feel the POCO make a monster Conneries* with the hook up and look at the meter face see what it say it should say 240 volts if so you need to get this situation straghten out if you have old school round meter socket that will be pretty much history now.

Merci,Marc

* French word for bull****
Merci, Marc, je le pense aussi (did I say that right?)

Indeed, my meter says 240V. Perhaps I'm getting free power if it's not reading right , or paying too much .

The main breaker is 150A (odd number..). I attach a pdf....sorry I don't know how to resize it for a gif. Note the RHS is all breakers 20A, the LHS all 15A. There are 19 breakers in all (I think 18 and 20 is a tandem, Jamie?) and 11 neutrals. The incoming red and black have 0V between them.

BTW, there is some splicing in the panel (for a doorbell transformer). I understand this is not code?

Cheers
Tyro
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Old 03-01-2009, 07:11 PM   #29
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Merci, Marc, je le pense aussi (did I say that right?)

Indeed, my meter says 240V. Perhaps I'm getting free power if it's not reading right , or paying too much .

The main breaker is 150A (odd number..). I attach a pdf....sorry I don't know how to resize it for a gif. Note the RHS is all breakers 20A, the LHS all 15A. There are 19 breakers in all (I think 18 and 20 is a tandem, Jamie?) and 11 neutrals. The incoming red and black have 0V between them.

BTW, there is some splicing in the panel (for a doorbell transformer). I understand this is not code?

Cheers
Tyro
Tyro ., you did speak right .,

Now let get on serious matter here .,

If you read the voltage on large conductors AKA main cable if you read both black and red you should able ring up full 240 volts if not half of the house will have power on that it.

If you have differnt test meter check it with it sometime a test meter can malfuction if not carefull.

Yeah you have 150 amp service there.

The bottom right breaker that is tandem breaker if you have both black and red conductors with single netural { white conductor } that need to be changed over to fullsize breaker for safety issue due the netural conductor current rating.

As far for doorbell set up some are it is legit to do that most of the time I just stick it outside of the box for low voltage connections for line voltage it must be inside the junction box or on the breaker KO opening.

Call the ConEd again but get a hold of supervisor and get the details straght on this matter they should not goof up on this one.

Merci,Marc
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Old 03-01-2009, 07:21 PM   #30
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Why are there no grounds?

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