Two branch circuits mated together....

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rimkemeier

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Data Center Operations Electrician
Hi,

Reposting as I did not have my occupation updated with Electrician. Commercial electrician here...

I discovered two branch circuits in a residential main panel that are tied together somewhere in the home. I was trying to locate a breaker to disconnect power and found that two breakers, (both 20a thankfully) need to be turned off to disconnect power. My initial response is to pull the wire off of one breaker and cap it. Not sure how I am going to find the JB where they are mated. Anyone ever come across this?

Thank you,
Ryan
 
rimkemeier said:
Hi,

Reposting as I did not have my occupation updated with Electrician. Commercial electrician here...

I discovered two branch circuits in a residential main panel that are tied together somewhere in the home. I was trying to locate a breaker to disconnect power and found that two breakers, (both 20a thankfully) need to be turned off to disconnect power. My initial response is to pull the wire off of one breaker and cap it. Not sure how I am going to find the JB where they are mated. Anyone ever come across this?

Thank you,
Ryan
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Yes, it happens.
 
Depending on what outlets are supplied, you might have some more obvious signs of what should have been separated and can possibly go separate at an outlet location if you feel that two circuits are definitely needed.
 
Both must be on same phase or the breaker would have tripped.
Unbelievably, yes seen more that I'd like.
Both that trip a breaker and where need to turn off 2 breakers to kill circuit.
Load calculation for the "2" circuits would be advised before just leaving unconnected from one breaker to ensure not overloading. (post #6)

Un-connect and use of a fox and hound then basically either get lucky or search every box. Have found buried Jbox with this method that had a multi-tap because tone went into 3 directions in a ceiling from a central point. Disconnect both then trace, free up neutrals at panel also to reduce multiple backfeed signals.
 
Leaving it capped off is safer than leaving it connected. If that was two 15 amp circuits it would take at least 30 amps to trip one of them.
 
I fixed one where there were two service panels (400 Amp service), and a breaker in each panel fed the same receptacles. It was two kitchen receptacle circuits (of several, large house big kitchen), and I was doing something on the circuit (been a while as to why I was there) and sure enough I found it in the second box I was working on i.e. hmm, seems like a lot of Romex coming in here. Looked original to the house, not DIY change.
 
In a house, it's probably not a junction box you're looking for. The 2 most likely scenarios:

1) one circuit was mistakenly fed at both ends

2) two circuits were mistakenly joined together with a jumper

The best thing to do is find exactly what all turns off when both breakers are shut off, then determine (or decide) if it should be one circuit or two.

If it's only one circuit, cap it in the panel.

If it's two circuits, open up a receptacle then disconnect and cap off there
 
I found that in a 50 year old house. two circuits tied together at the end of each circuit in a box for a closet light. Lucky the cables were exposed in the attic so we could trace them.

I was installing a sub panel with a generator interlock. Figuring what circuits to put on the gen panel. Shut off half the panel then turned that on and killed the other half. Had 2 circuits that never went dead
 
Honestly I almost think it's better to pigtail the two hots together on one breaker than to cap one off in the panel. Otherwise the next guy comes along, sees a capped off wire, and doesn't know whether it's hot, or what turns it off.

I know, I know, it's illegal parallel conductors but that was already the situation so unless you find the wiring error in the house and fix that then it's the same as it was.
 
Divide and conquer is the cheapest, but not easiest way to find it. An Amprobe current tracer would be easier, but more expensive. Don’t know whether Greenlee or Ideal tracers would work, as they inject a signal instead of drawing a current pulse off the circuit.
 
Do mental troubleshooting first.

What outlets/loads are on the two breakers?

Is it one or two circuits' worth of loads?

Are all of the affected outlets related?
 
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