[jbone64]

I have two 15A circuits in my panel labeled "lights" (breaker 18A) and "office" 26B. They are wired correctly at the panel. If I turn the breaker off at 18A, both the "office" and "lights" still have power AND the black wire at 18A is hot (back feeding?). If I only turn off the breaker 26B, the same thing occurs. Power still to the "lights" and "office" and the black wire at 26B is hot. I must turn off both circuits to turn off the power to "lights" and "office" and then both blacks go cold. In the basement I have found both home run wires for the circuits and where they are entering the floor into the walls at where I would expect for the rooms . I believe the office circuit should only power a light and 4 sockets. One of those sockets being a half switched. Which is working. The "lights" circuit goes to a 4 gang with all 3way switches. Three of the switches are controlling the effected "lights". The forth is for "kitchen lights".
I had electrician come out and he said, the builder "accidentally" dropped two home runs for the same circuit. Although both circuits are clearly labeled as separate circuits and common sense says they are separate. His solution was to just disconnect black and white wires for circuit 26B and roll them up in the panel. The black wire is still HOT. Circuit 18A now has all the 12 outlets. This does not sound correct. I believe I still have a black wire being being back fed. Now it's just rolled up in the service panel.
Is this the way to fix the problem or do I call another electrician? Sorry for the length of post.

 

[daveb1]

How are you determining that the circuits have power, with a voltage detector, a meter, or do the lights actually still work?

Can you determine a place in your house where both circuits may meet and then branch apart? Where is the office in relation to the bedroom?

 

[joed]

There is a cross connect somewhere. If you trace the cables you will likely find one box where both circuits meet. If there are switches from each circuit in the same box that is a likely place.

 

[jbone64]

The lights still work with the breaker off and a volt meter.
I found the home run for one of the circuits (18A), the one I'm using. It comes into light switch in the foyer. It pigtails to feed a single pole light switch there. It then connects to wall switch in the office, back to back. Which I believe is the end run location for circuit 26B. If it stopped there, problem solved. Unfortunately the wall switch in the office has to connect to feed all the sockets in the office. Then (I assume) it feeds the lights on the "light circuit" (4 gang box) where I hope to find that is also where the disconnected 26B ties back in. I haven't found where the problem is, but I have found where it isn't.

But if I can't find and fix the issue is it safe to disconnect circuit 26B. Let it continue to back feed from 18A, and have it terminate in the panel with a wire nut on the hot and neutral wire? The electricians says it's fine. Thanks

 

[surferdude2]

It's not great and not code legal. I wouldn't worry too much about it since it's not a dangerous situation. Personally I'd track the cross connection down by using a tick tracer or "Hound & Hare" type signal tracer. It too bad the original wiring crew didn't choose opposing phases for the two feeds so the breakers would have blown and they would have fixed things. Their ignorance provided bliss and passed the problem on to you. :sad:

 

[Old Thomas]

My son bought a house that had that situation and it took me a while to figure it out. I did what your electrician said and then I used the spare breaker to power a light over the panel since it was a poorly lighted spot.

 

[gthomson]

Wow - I was just going to ask almost an identical kind of question tonight.
I started a room remodel a dozen years ago, and it all got put on hold for budget reasons. Finally getting back to it now.
The walls and flooring have been gone the whole time, and I had an electrician add a couple circuits, some additional switches and some additional receptacles.
I want to get the changes permitted before I put the walls back up.
The company that did the work closed up for awhile, then opened up under another name. So I'm not sure what that's all about, but figured I'd try to figure it out myself, or call another, but bigger, company to help this time.
Found two circuits going into a 2 gang box for receptacles.
Possibly it's like what somebody mentioned - I have a 3 gang box for switches, and they handle things on both circuits?
So I started checking further with a tester device to see which receptacles go to which breakers, as they aren't well labeled at the breaker box.
So far, every receptacle I've tried in the house - one in each room and garage in a couple locations...
All trigger the tester to beep at two breakers within the panel that are not next to each other. So it's not just proximity that's triggering two breaker locations to start the device beeping - they're a good 5-6" apart in the box.
I'm new to learning electric in a house, so that's why I came here, to ask if that's standard.
Scared me a little to see it was like that, and so far on all the receptacles I've tested.
So I have to make doubly sure (no pun intended) that I've got power off when working on things - I was used to only having to turn off one breaker, but I'll now check with another tester for a hot wire, and also the tracer to find the breakers feeding the things I'm working on.

I'm going to ask the city permit guy when I get the inspection done if that's normal for the area.

I don't know if this is useful info, but the house is in Southern California, built in about 1984 I believe. I just mention in case there are others in the area that were built around the same time, and have the same thing.

This is also one of my projects for this three day weekend - I want to do a more thorough checking on things to see if all receptacles are like this in the house.

 

[Wiredindallas]

It may not be your situation, but perhaps one half of the receptacles were intended to be controlled by a switch and the tab between the 2 screws was not removed to sesperate the 2 circuits.

 

[surferdude2]

@gthomson
Your tester could be misleading you. If it isn't a direct contact type, such as a voltage test using a multimeter, the results can be confusing.

It's not uncommon for two circuits to feed into the same j-box. If they are on separate incoming cables, it doesn't matter which breakers they land on in he panel. However, if they are both on one single incoming 12/3 cable, they must land on different phase breakers in the panel. The latter is unusual but mentioned as a possibility.

A good way to make sure all is well before closing the walls is to turn off one of those breakers and see which circuits go dead. Then repeat that with the other breaker to see that there is nothing common involved.

 

[dmxtothemax]

Maybe someone using a ring main ?

 

[surferdude2]

Maybe someone using a ring main ?

Good point if they are in the UK or elsewhere that permits that.

I think the only time that's used where I live (US) is when the power company connects all their transformer primaries in a ring. That makes it easy to isolate a failed underground and get everybody back on line quickly.

 

[Old Thomas]

The UK used to allow loop circuits, not sure if they do now. In a loop circuit the wire from the breaker travels out to the loads and the last load has a wire returning to the same breaker, forming a loop. The theory is that with two paths half the current goes each way, requiring much smaller wire. It is not allowed in the US because if a wire is disabled all the current goes on the other wire possibly overloading it because it is undersized. In the case I mentioned, it was wired in a loop with each end at separate breakers. The wire was sized properly so it was not a fire risk. It was dangerous because when I turned off one breaker the circuit was still energized.

 

[joed]

A ring main would not use two breakers. If I understand it correctly, it loops back onto the same breaker.

 

[Wiredindallas]

The UK used to allow loop circuits, not sure if they do now. In a loop circuit the wire from the breaker travels out to the loads and the last load has a wire returning to the same breaker, forming a loop. The theory is that with two paths half the current goes each way, requiring much smaller wire. It is not allowed in the US because if a wire is disabled all the current goes on the other wire possibly overloading it because it is undersized. In the case I mentioned, it was wired in a loop with each end at separate breakers. The wire was sized properly so it was not a fire risk. It was dangerous because when I turned off one breaker the circuit was still energized.

Well, proves one is never too old to learn. At 68 I never heard about that. Believe me, I will still never to that! Can you imagine someone putting the other end of a loop on the opposite phase?

 

[gthomson]

@gthomson
Your tester could be misleading you.

I think you were right on that. I spent a few hours today trying to map out all circuits to where they go. I think I have most all mapped now, and they were so different than how the panel was labeled.

A piece I don't understand still... there are 2 x 100amp breakers tied together in the panel. If those are off, everything is off. If those are on, then as I turn on another breaker, those on that circuit become active.

Could those 2 x 100 amp breakers be considered like a common for the whole house?

 

[joed]

The double pole 100 amp breaker is main disconnect that turns off power to the whole panel.

 

[surferdude2]

Yes, that's the Main breaker. Doing it that way requires that breaker to be screwed in permanently to be code compliant.

That is known as a backfed breaker main. The reason it must be screwed in to hold it permanently is for safety. If someone pulls that breaker or it falls out accidentally, it will still be live since the feeder wires come directly from the meter. A person grabbing hold of it to put it back in its place could be harmed.

Does your main have a screw or screws in it?

 

[gthomson]

Does your main have a screw or screws in it?

This is my panel, with the 2 x 100 amp breakers in the middle.
Disregard all the sharpie labels, I'm finding they aren't matching up with what is.

I'm thinking the screw setup applies to a different kind of panel?
Or do I need to take off that panel cover to understand things better on this?

 

[fa_f3_20]

Man, that's a gnarly-looking panel. I think this is what is known as a split-bus panel. That 100-amp main breaker probably only controls the circuits below it; the ones above it are probably independent. I'm not sure what's up with that red breaker with what appears to be a lockout device on it.

 

[surferdude2]

On your panel, the hold down method isn't visible until you remove the panel front cover.