Same circuit fed twice
- Thread starter 2_BEARS
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: Same circuit fed twice
Not OK. Now you have part of one circuit with an OCPD of 40 amps. You need to trace the entire circuit(s) out and find where they are connected together. Putting the two circuits one the same phase effectively doubles the ampacity of the OCPD protecting it. Somewhere along that #12 wire it may be protected by 40 amps of OCPD.
Not OK. Now you have part of one circuit with an OCPD of 40 amps. You need to trace the entire circuit(s) out and find where they are connected together. Putting the two circuits one the same phase effectively doubles the ampacity of the OCPD protecting it. Somewhere along that #12 wire it may be protected by 40 amps of OCPD.
ty
Senior Member
- Location
- 3rd Rock from the Sun
Re: Same circuit fed twice
Rip it apart, find the jumper, and disconnect it.
I agree.
Rip it apart, find the jumper, and disconnect it.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Same circuit fed twice
2 Bears, do you think that the loop was pulled somewhere inside the house accidentally (as in, between outlets), or that someone accidentally pulled two home runs to the panel?
If the "two" together would be acceptable as one circuit, I would consider abandoning the extra home run in the panel (with a very descriptive label on it).
Just a thought.
Besides, it looks better when you use a marker.
2 Bears, do you think that the loop was pulled somewhere inside the house accidentally (as in, between outlets), or that someone accidentally pulled two home runs to the panel?
If the "two" together would be acceptable as one circuit, I would consider abandoning the extra home run in the panel (with a very descriptive label on it).
Just a thought.
Why is this considered such a "burn them at the stake" violation? Yes, it's code, yes, I do it, but it always kinda makes me giggle a little when someone brings it up.
Besides, it looks better when you use a marker.
growler
Senior Member
- Location
- Atlanta,GA
Re: Same circuit fed twice
2_Bears, when you take over a job it's yours, mistakes and all. The people that did the rough will not be blamed so you have to find all the faults. My guess is that this is not really a mistake on the rough but a trim failure. Probably two circuits in a muti-gang switch box and all the lights were wired as if on one circuit. There are not many places where you would have a change to cross two circuits in residential. The switch box in the foyer often has two different circuits and could easily get wired wrong if the 3-way for stairway lights is fed from the wrong end.
2_Bears, when you take over a job it's yours, mistakes and all. The people that did the rough will not be blamed so you have to find all the faults. My guess is that this is not really a mistake on the rough but a trim failure. Probably two circuits in a muti-gang switch box and all the lights were wired as if on one circuit. There are not many places where you would have a change to cross two circuits in residential. The switch box in the foyer often has two different circuits and could easily get wired wrong if the 3-way for stairway lights is fed from the wrong end.
allenwayne
Senior Member
Re: Same circuit fed twice
Taking over a job from another is usually a nightmare since if the original electrician was qualified he more than likely would have finished the job.From what you stated it sounds like a residential project and how long can it posibly take to wire a house?I have done homes from 1,000 sq ft. to 32,000 sq ft. and the time ranged from 3/4 of a day to 2 weeks.We had a guy that bailed on a 10,000 sq ft. as I was doing 2 others at the same time and it was dropped in my lap.What I found would astonish even a 1 year helper.Thakfully it was in rough and the time it took to correct was minimal.BTW he was in trade for 15 years but did service for past 12 years.
Some items found were bath gfci with outdoor gfci,30 ft ceiling and dining light was deleted so he wired the dining room from general purpose circuit,100 amp sub panel on other side of home fed 6 120v gen.purpose circuits,waterheater,8 kw a/h/u,jetted tub and a 30 amp a/c unit and a sauna.To top it off the 400 amp service was in the wrong location so had to relocate the meter and SER both panels.
So if all there were are some bad joints and a double feed thank the stars.Fix it and move on.
Taking over a job from another is usually a nightmare since if the original electrician was qualified he more than likely would have finished the job.From what you stated it sounds like a residential project and how long can it posibly take to wire a house?I have done homes from 1,000 sq ft. to 32,000 sq ft. and the time ranged from 3/4 of a day to 2 weeks.We had a guy that bailed on a 10,000 sq ft. as I was doing 2 others at the same time and it was dropped in my lap.What I found would astonish even a 1 year helper.Thakfully it was in rough and the time it took to correct was minimal.BTW he was in trade for 15 years but did service for past 12 years.
Some items found were bath gfci with outdoor gfci,30 ft ceiling and dining light was deleted so he wired the dining room from general purpose circuit,100 amp sub panel on other side of home fed 6 120v gen.purpose circuits,waterheater,8 kw a/h/u,jetted tub and a 30 amp a/c unit and a sauna.To top it off the 400 amp service was in the wrong location so had to relocate the meter and SER both panels.
So if all there were are some bad joints and a double feed thank the stars.Fix it and move on.
Re: Same circuit fed twice
Ahhh, that can happen of an electrician is feeding the same yoke, such as an duplex outlet is a kitchen, with homerun (2) 20a circuits and plain forgot to clip the jumper on the line side of the outlet.
If it is a homerun circuit close one breaker and trace one line with a signal tracer to see where that leads. Then open that breaker and close the other to see of they end up in the same places. Then open the boxes and inspect those locations.
Ahhh, that can happen of an electrician is feeding the same yoke, such as an duplex outlet is a kitchen, with homerun (2) 20a circuits and plain forgot to clip the jumper on the line side of the outlet.
If it is a homerun circuit close one breaker and trace one line with a signal tracer to see where that leads. Then open that breaker and close the other to see of they end up in the same places. Then open the boxes and inspect those locations.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Re: Same circuit fed twice
[ February 11, 2006, 10:50 AM: Message edited by: hardworkingstiff ]
This is confusing to me. Are you saying if breaker 1 (just for discussion) is on, breaker 2 has 120 volts on it fed from breaker 1 and vice versa, but breaker 1 does not energize some devices that breaker 2 does energize (and vice versa)?Originally posted by 2_BEARS:
Unacceptable. Turns out that the original suspect circuit is indeed being fed twice BUT
[ February 11, 2006, 10:50 AM: Message edited by: hardworkingstiff ]
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: Same circuit fed twice
NO not at all ok for reasons already mentioned.You scare me that you would even suggest that as a cure.What often happens on jobs is that more than 1 man has his hands into one circuit.When possable i prefer same man that ran the wire splices it too.Your way out here is to turn only one breaker on this circuit with everyother breaker off.Now see what all is on it and seperate it in the correct box so that the load is equal.What gets scarry is that this was a 50-50 chance of you never even knowing there was a problem had they been on same leg.
NO not at all ok for reasons already mentioned.You scare me that you would even suggest that as a cure.What often happens on jobs is that more than 1 man has his hands into one circuit.When possable i prefer same man that ran the wire splices it too.Your way out here is to turn only one breaker on this circuit with everyother breaker off.Now see what all is on it and seperate it in the correct box so that the load is equal.What gets scarry is that this was a 50-50 chance of you never even knowing there was a problem had they been on same leg.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Same circuit fed twice
I can't imagine a scenario where the two circuits are combined, but somehow individually fail to energize everything. There's no way.
I regarded that as an impossibility, so I read that as saying that the combined circuit is larger than 2-Bears would like. Or, "some other devices" could mean a circuit required to be separate, such as required in 210.11(C).Originally posted by hardworkingstiff:
This is confusing to me. Are you saying if breaker 1 (just for discussion) is on, breaker 2 has 120 volts on it fed from breaker 1 and vice versa, but breaker 1 does not energize some devices that breaker 2 does energize (and vice versa)?Originally posted by 2_BEARS:
Unacceptable. Turns out that the original suspect circuit is indeed being fed twice BUT
I can't imagine a scenario where the two circuits are combined, but somehow individually fail to energize everything. There's no way.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Same circuit fed twice
Originally posted by Jhr:
Please explain in more detail
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Re: Same circuit fed twice
I agree George, hence the question. They way the OP was presented seemed to suggest this, and it does not seem possible.
I agree George, hence the question. They way the OP was presented seemed to suggest this, and it does not seem possible.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Re: Same circuit fed twice
As far as the 40-amp OCP, I believe we need to consider the following (it is still against the code to parallel OCP). If the circuits don't extend as one cable after they are joined, then the conductors will still be protected at 20-amps. If the cable is extended after the circuits come together then that cable will be protected at 40-amps (assuming equal resistance back to the OCP devices).
Any device plugged into a receptacle or wired into the circuit will be protected at 40-amps (with the same assumptions as above).
No matter what, this is not in compliance with the NEC and is dangerous!
As far as the 40-amp OCP, I believe we need to consider the following (it is still against the code to parallel OCP). If the circuits don't extend as one cable after they are joined, then the conductors will still be protected at 20-amps. If the cable is extended after the circuits come together then that cable will be protected at 40-amps (assuming equal resistance back to the OCP devices).
Any device plugged into a receptacle or wired into the circuit will be protected at 40-amps (with the same assumptions as above).
No matter what, this is not in compliance with the NEC and is dangerous!
Re: Same circuit fed twice
[ February 11, 2006, 12:48 PM: Message edited by: augie47 ]
that is a scarry point, Jim. Makes one wonder how often this situation might exists. I encountered it one time in a commercial office building (1 circuit, two breakers, same phase)attempting to turn off a circuit by turning off 1 breaker at a time. Looked at a lot of panelboards before we discovered what was happpening. (circuit tracer was going nuts)
[ February 11, 2006, 12:48 PM: Message edited by: augie47 ]
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: Same circuit fed twice
Hi Roger,
As drawn, and assuming the two breakers shown are on the same phase, there is no current in the resistance of the load.
There needs to be a neutral connected somewhere along the load.
Just nitpicking. . .
Hi Roger,
As drawn, and assuming the two breakers shown are on the same phase, there is no current in the resistance of the load.
There needs to be a neutral connected somewhere along the load.
Just nitpicking. . .
Re: Same circuit fed twice
. A two pole 20amp breaker is still a 20amp breaker not a breaker that cannot withstand 40amps and will trip after 20amps is exceded. What needs to be done is trace down where the two circuits are spliced together.
[ February 11, 2006, 02:36 PM: Message edited by: Jhr ]
Is this your theory, because a 20amp Brkr. will trip after 20amps is exceded, where do you come up with 40amps, and how do know that the current divides at the center. IMO this is still a 20amp circuit that will trip when 20amps is exceded
. A two pole 20amp breaker is still a 20amp breaker not a breaker that cannot withstand 40amps and will trip after 20amps is exceded. What needs to be done is trace down where the two circuits are spliced together.[ February 11, 2006, 02:36 PM: Message edited by: Jhr ]
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