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Two Breakers wired together?

8K views 26 replies 10 participants last post by  Oso954 
#1 ·
Just bought an old 2 bed 2 bath 1949 raised foundation home, 2 car garage, 1200 sq. ft. I have an old Zinsco box as seen in the pictures. At a point in time the house had an addition added on to it and new grounded circuits were added. I have turned each breaker off one by one and marked which lights, outlets, and what not are being turned off, so I can figure out what is on what circuit and if it is overloaded. I have a few questions. But it depends on what’s going on with this first question…

When I turn off breaker 1 or 3 nothing happens. Only when I turn off breakers 1 (15AMP) AND 3 (20AMP) is when the power is turned off to the circuits. But when they are both turned off A LOT of thing are turned off in the house. All plugs and lights in the guest bedroom (2 plugs and 1 ceiling fan), All plugs and lights in the living room (3 plugs {one for fridge and TV}, and one ceiling fan), one porch light, 2 hall lights, a bathroom light, kitchen light, dining room ceiling fan, laundry light and plug, and the microwave plug are all off.
Now none of these things are in the new construction and as seen in the picture the RED wires from 1 and 3 go into the OLD box for the OLD construction.
Now to figure out the question.

Judging by the wire coming out of breakers 1 and 3, I’d say they are close to a 10 gauge wire, which I believe is rated for about 35A. Now with both breakers in parallel the amperage is 35A. So it kind of makes sense there are so many things on one circuit, that for whatever reason was never put on a single breaker but used two existing breakers to get 35A. And the plugs and lights are definitely not 10 gauge at the wall but I think it is all 12 gauge.

So, is this something that somebody has seen or done before? I also attached a spreadsheet of everything that the breakers are controlling. Note there are multiple breakers that do nothing when turned off. I also have another 240V circuit that I can’t find anywhere. One is for the current AC that was recently installed, and the other is untraceable and I can’t find it and it seems to do nothing.

A little more info about the house…
Used to have a gas floor furnace, from what I can tell always had gas dryer, gas stove. It used to have a large wall AC unit or swamp cooler installed on one wall, but it’s got a dedicated 120V circuit right next to it and another junction box next to it on a separate circuit that is 120V as well (So I imagine it was never wired for 240V since a dedicated 120V circuit is right next to it). Then a 240V circuit was clearly added for the central AC unit in the backyard.

Any help or incite to this much appreciated! :thumbup:
 

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#3 ·
Any tricks to diagnosing this or is it just a matter of pulling plugs out of the wall and looking for interconnections, separating and then testing the breaker to see if it kills that line?

Also I have a no contact tester and only with this circuit, when both 1 & 3 is off, everything still beeps by the tester saying there is power but when I test for voltage its like .4V. What explains this?
 
#4 ·
You don't have a 200 amp service, it is a 100 amp service.

For some reason, someone has installed the main breaker upside down.
I suggest you should have an electrician pull it and, inspect to see if he can determine if it is safe to turn it around correctly.

I suspect that your deadfront panel is missing. (it is an interior panel that covers the breakers & wiring, only leaving the breaker switches exposed.) A missing deadfront is a big safety problem.

You have a suspected interconnection between 1 and 3. You will probably need an Electricians help to find the interconnection.

You say that #7,10, 11&12 do nothing. If they really do not shut the power off (even if you don't know where that power goes) you HAVE a BIG Problem.
Even if they do shut the power off, you might have an interconnection between #7&10. Did you try turning those off at the same time ?

It is a Zinsco Panel.

Do not be surprised if the electrician recommends a panel replacement.
 
#5 ·
*As electricians we have all experienced some crazy wiring in our careers. However there is no set rules or steps to troubleshoot that will ultimately lead to fixing the problem. There have been occasions where it is faster and easier to run new wiring instead of tracing the old. Sometimes I found a buried box just by luck.

In your circumstance I would want to see what is going on in that old service. Since you mentioned that both circuits go there, it makes sense to follow that path. I would also try shutting off all two pole circuit breakers to see if that changes anything.

Off the top of my head it sounds as though those two red wires might be feeding the old circuit breaker panel from which the old existing wiring branches out from. Those two breakers may very well be the main for the old service.
 
#8 ·
I think that is a very good possibility and would explain this. But there is no access to the old service spot, and there cant be any other fuses or breakers in there, So that still leaves all the old service lines on 1 & 3, and that seems unsafe doesn't it? I have 14 gauge and 12 gauge in the walls at the plugs and if its on a 35A trip wouldn't it burn up 14 gauge wires?

I tried shutting off all two pole circuit breakers and it is the same result, nothing changes.
 
#6 · (Edited)
Do you own a voltmeter? Are you familiar with how to use it?

If so, I'd turn off all breakers (not main) except #1.
Test all other breakers to see if no power. Any that test hot are back fed.
Now see what is hot and not to see what is being fed. That will tell you where to look anyway.

Repeat for other breakers to confirm no other issues.

The upside down main is another issue.

MeTV has a good observation too. The two feeding a sub.
 
#7 ·
You don't have a 200 amp service, it is a 100 amp service.

Ok

For some reason, someone has installed the main breaker upside down.
I suggest you should have an electrician pull it and, inspect to see if he can determine if it is safe to turn it around correctly.

Ok

I suspect that your deadfront panel is missing. (it is an interior panel that covers the breakers & wiring, only leaving the breaker switches exposed.) A missing deadfront is a big safety problem.

No I have it.

You have a suspected interconnection between 1 and 3. You will probably need an Electricians help to find the interconnection.

You say that #7,10, 11&12 do nothing. If they really do not shut the power off (even if you don't know where that power goes) you HAVE a BIG Problem.
Even if they do shut the power off, you might have an interconnection between #7&10. Did you try turning those off at the same time ?

They turn the line off, I just meant I cant find anything in the house that is on that circuit. Everything in the house is being controlled without using those breakers, from what I can see. 11 & 12 is 240V and the only 240V I can find goes to the central AC, and all junction boxes have 120V.

It is a Zinsco Panel.

Yes, I know. :(

Do not be surprised if the electrician recommends a panel replacement.

Ok
 
#13 ·
Im guessing (All comments appreciated) that the two red wires are feeding the original circuit that had everything on it, which maybe went to a 35A fuse. (There is also a huge ground wire following out of the old service panel) When the new service was installed, instead of separating that one heavy circuit into 2 or 3 15/20A circuits, they just ran it to a 20A and 15A, in order to match the 35A fuse. And maybe a 35A breaker isnt available and they didnt want to use a 40A and cause possible hot wire issues.

What doesn't make sense to me with this idea is that why would there be two wires coming from the old service that is running one large circuit now. Could it be that they were wired in a similar fashion on fuses? One 20A fuse in parallel with a 15A fuse? Im not familiar with the old fuse style boxes and how they wired them and what fuses were available.
 
#14 ·
From my basic knowledge, temperature has nothing to do with it.
Most of the modern circuit breakers have two trip mechanisms. One is electromagnetic and the other is temperature.
http://www.engineersgarage.com/insight/how-mcb-works

The wiring interconnecting your circuits was never done intentionally. It is most likely that a handyman or inexperianced DIYer committed the error while attempting to do something else.
 
#15 ·
Why would the upside down breaker be an issue?
Because the breaker is designed to go in one way. It hasn't been safety tested with the breaker upside down.

On your panel, the deadfront will not fit properly with the breaker upside down. So, you don't have it in place, or your forcing it in place, or someone enlarged the hole. There are safety hazards with all 3 approaches.
 
#16 ·
I will re state what I believe you should do. Shut off all breakers except for #1.

Check to see if #3 is hot.

If yes, check for everything that has power.

Maybe then you may see where it needs to be separated.

Maybe you have a lighting circuit and an outlet circuit.

Something that gives you a clue.

Either way. Once you see what's hot. Pick a place you think is in the middle and open up to investigate.

Repeat for 7 and 8 and Check all neutral connections.
 
#17 ·
I will re state what I believe you should do. Shut off all breakers except for #1.

Check to see if #3 is hot.

If yes, check for everything that has power.

Maybe then you may see where it needs to be separated.

Maybe you have a lighting circuit and an outlet circuit.

Something that gives you a clue.

Either way. Once you see what's hot. Pick a place you think is in the middle and open up to investigate.


Repeat for 7 and 8 and Check all neutral connections.
Oh alright I think I misunderstood your original response.

My question is then, if 1&3 are interconnected, and 1 is on but 3 is off, and 3 shows power, then wouldn't everything in the house on 1 or 3 have power as well? It seems like whatever I have on or off (1 or 3) I get the same results in the house. But maybe I need to take a closer look?

As for 7 and 8, For starts...I originally had (I don't know the technical name for it) a twin breaker that could only be turned on and off together. I replaced it with one that can be turned on/off individually as it went bad. Now that I can turn it on/off individually, I turn one off and leave one on and one has 120V while the other has 40V and vice versa. What would explain that??

Lastly, what is my real concern for having interconnected circuits? I was thinking originally that if you have a total of 35A and don't have the wire to support it, that you risk burning up the wires before the breaker trips. But after being previously told they are also tripped by temperature, whats there really to worry about? Of course id rather do it the right way, but what am I really risking. That maybe since there is larger gauge at the service panel and smaller gauge in the house that the wires in the house would burn up first?
 
#18 · (Edited)
The premise is to VERIFY what is going on. Nothing wrong with testing and noting what you're reading.

One problem of an interconnected circuit is this, what if you have a hot leg burn up? At a device or say in the middle of a run. How will you know you have a potentially dangerous situation? If it's in the middle of the loop how will you know as it has 2 feeds?

Secondly, you have 2 differently rated breakers. How do you know you have proper wire along the whole circuit for the larger breaker?
Just not a good set up.
Breaker 7 and 8 I don't know, that could depend on what's connected to it.
 
#19 ·
As an additional note:
Breakers are not to protect against crap workmanship, although they can. The very existence of the NEC is to presumably protect life and property. Otherwise all you need is breakers and gfci/afci. Nothing else would really matter. Wire to your hearts content.

The safety factor is greatly increased or reduced based on following the code and by not doing anything inherently stupid.

IMHO
 
#20 ·
ok back to the these two questions...

My question is then, if 1&3 are interconnected, and 1 is on but 3 is off, and 3 shows power, then wouldn't everything in the house on 1 or 3 have power as well? It seems like whatever I have on or off (1 or 3) I get the same results in the house. But maybe I need to take a closer look?

As for 7 and 8, For starts...I originally had (I don't know the technical name for it) a twin breaker that could only be turned on and off together. I replaced it with one that can be turned on/off individually as it went bad. Now that I can turn it on/off individually, I turn one off and leave one on and one has 120V while the other has 40V and vice versa. What would explain that??
 
#21 ·
If either 1 or 3 is off, then everything in the house on either of those two circuits will test live, as they are interconnected. With one or other breaker off, the portion of the hybrid circuit fed from the de energized breaker is still live because it is being backfed by the breaker still energized. You must find this interconnection and break it. It is not proper practice to have a circuit fed in parallel from two breakers, not to mention that the two breakers have different ratings, are not handle tied or even adjacent, and some of the field wiring is not a sufficient gauge to carry 35 amps. As for 7 & 8, if you removed a handle tied breaker you should replace it with a handle tied breaker. It is either a 240v load or two 120v loads sharing a neutral. In fact they may be sharing a neutral which is open, so when you only energize one you are reading the remaining voltage not being dropped across the load. You should call an electrician.


Sent from my iPhone using Tapatalk
 
#22 ·
There's some sort of misunderstanding.

If 1 is on, 3 is off and 3 tests hot at the breaker, there's no doubt it is connected. Just suggesting you make sure.

Now, determine what is hot, lights, outlets, switches.

Once you do that, look for a pattern. See what lights are on, go to the end of the lights and see if you can separate there, or some similar spot. Look for different wire sizes etc. See if you can find a logical place to divide the circuit between the 2 breakers.
 
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