BRANCH CIRCUIT
- Thread starter sammy
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Senior Member
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- New York, 40.7514,-73.9925
Re: BRANCH CIRCUIT
As long as you do not overload the circuit, and you consider max VA permitted on that circuit (220.3), then assuming it's a trick question, I'll say infinite.
As long as you do not overload the circuit, and you consider max VA permitted on that circuit (220.3), then assuming it's a trick question, I'll say infinite.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: BRANCH CIRCUIT
Since the question included the fact that this is a single phase circuit and that the Definition of this circuit would fall under a multi-wire circuit. and after reading the Definition. I would have to come to the conclusion that it would only allow one per phase and this total would be 2.
ARTICLE 100 Definitions
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
Since the question included the fact that this is a single phase circuit and that the Definition of this circuit would fall under a multi-wire circuit. and after reading the Definition. I would have to come to the conclusion that it would only allow one per phase and this total would be 2.
ARTICLE 100 Definitions
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: BRANCH CIRCUIT
I would think that as long as you had a 200% nuetral, you could share a nuetral with two conductors of the same phase. That being said, I agree that in theory the answer is infinite. For practicality, I agree with Hurk.
I would think that as long as you had a 200% nuetral, you could share a nuetral with two conductors of the same phase. That being said, I agree that in theory the answer is infinite. For practicality, I agree with Hurk.
Re: BRANCH CIRCUIT
If the branch circuit conductors aren't running to the same place, don't forget about 300.20 - conductors must be grouped together.
Also, I don't think it applies here, but if we were talking about feeders instead of branch circuits, 220.22 has rules for calculating the load.
Steve
If the branch circuit conductors aren't running to the same place, don't forget about 300.20 - conductors must be grouped together.
Also, I don't think it applies here, but if we were talking about feeders instead of branch circuits, 220.22 has rules for calculating the load.
Steve
david
Senior Member
- Location
- Pennsylvania
Re: BRANCH CIRCUIT
215.4 Feeders with Common Neutral.
(A) Feeders with Common Neutral. Two or three sets of 3-wire feeders or two sets of 4-wire or 5-wire feeders shall be permitted to utilize a common neutral.
(B) In Metal Raceway or Enclosure. Where installed in a metal raceway or other metal enclosure, all conductors of all feeders using a common neutral shall be enclosed within the same raceway or other enclosure as required in 300.20.
National Electrical Code Handbook McGraw-Hills Twenty-Fourth Edition page 195.
? A common neutral may be used only with feeders. It may never be used with branch circuits. A single neutral of a multi-wire branch circuit is not a ?common neutral?. It is the neutral of a single circuit even though the circuit may consist of 3 or 4 wires. A feeder common neutral is used with more than one feeder.?
If we except the above statement as true, and I do. Then the answer is only one neutral per branch circuit. A multi wire circuit single phase, will share the neutral with both phases but that is still a single circuit.
215.4 Feeders with Common Neutral.
(A) Feeders with Common Neutral. Two or three sets of 3-wire feeders or two sets of 4-wire or 5-wire feeders shall be permitted to utilize a common neutral.
(B) In Metal Raceway or Enclosure. Where installed in a metal raceway or other metal enclosure, all conductors of all feeders using a common neutral shall be enclosed within the same raceway or other enclosure as required in 300.20.
National Electrical Code Handbook McGraw-Hills Twenty-Fourth Edition page 195.
? A common neutral may be used only with feeders. It may never be used with branch circuits. A single neutral of a multi-wire branch circuit is not a ?common neutral?. It is the neutral of a single circuit even though the circuit may consist of 3 or 4 wires. A feeder common neutral is used with more than one feeder.?
If we except the above statement as true, and I do. Then the answer is only one neutral per branch circuit. A multi wire circuit single phase, will share the neutral with both phases but that is still a single circuit.
- Location
- Illinois
- Occupation
- retired electrician
Re: BRANCH CIRCUIT
David,
Does the handbook cite a code section that says branch circuits can't have a common neutral? I've always been taught that you can't use common neutrals, but a couple of years ago I was challenged to cite a code section forbidding common neutrals, but have been unable to find one.
Don
David,
Does the handbook cite a code section that says branch circuits can't have a common neutral? I've always been taught that you can't use common neutrals, but a couple of years ago I was challenged to cite a code section forbidding common neutrals, but have been unable to find one.
Don
david
Senior Member
- Location
- Pennsylvania
Re: BRANCH CIRCUIT
Don,
No. Joseph & Brian McPartland do not give an article that is specific in addressing this. Maybe you could write them and get their explanation of why there is no you shall not.
It only comes from the fact that multi-wire branch circuits are defined in the NEC. And that sharing of common neutrals is only addressed with feeders.
If you going to design a branch circuit it has to meet the definition of branch circuits given in the NEC.
Brian J. McPortland
Electrical Inspector
New York Board of fire Underwriters
Tappan, New York
David
[ August 25, 2003, 04:25 PM: Message edited by: david ]
Don,
No. Joseph & Brian McPartland do not give an article that is specific in addressing this. Maybe you could write them and get their explanation of why there is no you shall not.
It only comes from the fact that multi-wire branch circuits are defined in the NEC. And that sharing of common neutrals is only addressed with feeders.
If you going to design a branch circuit it has to meet the definition of branch circuits given in the NEC.
Brian J. McPortland
Electrical Inspector
New York Board of fire Underwriters
Tappan, New York
David
[ August 25, 2003, 04:25 PM: Message edited by: david ]
joe tedesco
Senior Member
- Location
- Boston, Massachusetts
Re: BRANCH CIRCUIT
225.7 Lighting Equipment Installed Outdoors.
(B) Common Neutral.
The ampacity of the neutral conductor shall not be less than the maximum net computed load current between the neutral and all ungrounded conductors connected to any one phase of the circuit.
See the NECH Exhibits 225-3 and 225-4
Looks like a properly sized common neutral for branch circuits is allowed outdoors.
www.joetedesco.com
[ August 25, 2003, 04:33 PM: Message edited by: joe tedesco ]
225.7 Lighting Equipment Installed Outdoors.
(B) Common Neutral.
The ampacity of the neutral conductor shall not be less than the maximum net computed load current between the neutral and all ungrounded conductors connected to any one phase of the circuit.
See the NECH Exhibits 225-3 and 225-4
Looks like a properly sized common neutral for branch circuits is allowed outdoors.
www.joetedesco.com
[ August 25, 2003, 04:33 PM: Message edited by: joe tedesco ]
david
Senior Member
- Location
- Pennsylvania
Re: BRANCH CIRCUIT
Handbook McGraw-Hill?s Twenty-Fourth Edition page 240.
225-7. Lighting equipment installed out doors. Part(B) permits a common neutral for outdoor branch circuits-something not permitted for indoor circuits(a neutral of a 3-phase, 4 wire circuit is not a common neutral).
Joe & Don I?ll have to research and see if there are other exceptions to common neutrals. It seems that common nuetrals are only allowed where there is specific permission to do so.
david
Handbook McGraw-Hill?s Twenty-Fourth Edition page 240.
225-7. Lighting equipment installed out doors. Part(B) permits a common neutral for outdoor branch circuits-something not permitted for indoor circuits(a neutral of a 3-phase, 4 wire circuit is not a common neutral).
Joe & Don I?ll have to research and see if there are other exceptions to common neutrals. It seems that common nuetrals are only allowed where there is specific permission to do so.
david
david
Senior Member
- Location
- Pennsylvania
Re: BRANCH CIRCUIT
Joe,
I?ll have to say excuse me, and thanks for the reminder to never say never. There is always an exception when it comes to the NEC.
The point I think that needs to be made the use of a common neutrals is the exception and not the rule.
[ August 25, 2003, 05:02 PM: Message edited by: david ]
Joe,
I?ll have to say excuse me, and thanks for the reminder to never say never. There is always an exception when it comes to the NEC.
The point I think that needs to be made the use of a common neutrals is the exception and not the rule.
[ August 25, 2003, 05:02 PM: Message edited by: david ]
- Location
- Illinois
- Occupation
- retired electrician
Re: BRANCH CIRCUIT
David,
Without a code section that says you can't use a common neutral, an inspector cannot legally cite a violation. I see that your profile says that you are an inspector. What code section will you cite on the violation notice?
Just because a handbook says you can't doesn't make it so. None of the handbooks are official interpretations of the NEC.
I see nothing in the defintion of branch circuit that would prohibit the use of common neutrals. What problem would a properly sized common neutral cause?
Don
[ August 25, 2003, 05:15 PM: Message edited by: don_resqcapt19 ]
David,
Without a code section that says you can't use a common neutral, an inspector cannot legally cite a violation. I see that your profile says that you are an inspector. What code section will you cite on the violation notice?
Just because a handbook says you can't doesn't make it so. None of the handbooks are official interpretations of the NEC.
I see nothing in the defintion of branch circuit that would prohibit the use of common neutrals. What problem would a properly sized common neutral cause?
Don
[ August 25, 2003, 05:15 PM: Message edited by: don_resqcapt19 ]
david
Senior Member
- Location
- Pennsylvania
Re: BRANCH CIRCUIT
?FOR SINGLE-PHASE, HOW MANY CIRCUITS CAN SHARE A NUETRAL FOR LIGHTING AND RECEPTACLE ONLY AND WHERE IS IT LOCATED IN THE CODE BOOK (ARTICAL).?
Sammy
Since your question is addressing a ?shared circuit? between lighting and receptacles and I think if this is a test question they are addressing a single multi-wire circuit.
I believe the correct answer is you can only have one neutral for a circuit. They are a few exceptions to this as addressed so far in this thread. One is for feeders and this is not applicable to your question. And they other is for out-door lighting branch circuits.
Since your question is a shared neutral between a rec. circuit and a lighting circuit I would guess the correct answer should be one circuit consisting of an A phase, B phase and the neutral.
That being said, if this were a test question I would answer that the neutral could be shared as Hurk said in his post.
David
?FOR SINGLE-PHASE, HOW MANY CIRCUITS CAN SHARE A NUETRAL FOR LIGHTING AND RECEPTACLE ONLY AND WHERE IS IT LOCATED IN THE CODE BOOK (ARTICAL).?
Sammy
Since your question is addressing a ?shared circuit? between lighting and receptacles and I think if this is a test question they are addressing a single multi-wire circuit.
I believe the correct answer is you can only have one neutral for a circuit. They are a few exceptions to this as addressed so far in this thread. One is for feeders and this is not applicable to your question. And they other is for out-door lighting branch circuits.
Since your question is a shared neutral between a rec. circuit and a lighting circuit I would guess the correct answer should be one circuit consisting of an A phase, B phase and the neutral.
That being said, if this were a test question I would answer that the neutral could be shared as Hurk said in his post.
David
websparky
Senior Member
- Location
- Cleveland, Ohio
Re: BRANCH CIRCUIT
Hi Don,
I'm thinking of,
Hi Don,
I'm thinking of,
if I was put on the spot!
Re: BRANCH CIRCUIT
Don:
"Without a code section that says you can't use a common neutral, an inspector cannot legally cite a violation."
I seem to remember a code section (although I can't find it now) that said you were only allowed to do what was specifically in the code book. That would seem to put the burden on the contractor to cite an article that allows a particular installation.
Does this sound familiar to anyone else?
Steve
Don:
"Without a code section that says you can't use a common neutral, an inspector cannot legally cite a violation."
I seem to remember a code section (although I can't find it now) that said you were only allowed to do what was specifically in the code book. That would seem to put the burden on the contractor to cite an article that allows a particular installation.
Does this sound familiar to anyone else?
Steve
david
Senior Member
- Location
- Pennsylvania
Re: BRANCH CIRCUIT
Don,
I have much respect for your opinion. And I see what you are saying.
There is nothing in the codebook that says you have to use a neutral. I think there are some things in the design of circuits that were considered basic. And the writers of the rules never imagined they would have to address every aspect of electrical design with thou shall not. I am not a Benjamin Franklin and if I weigh every rule in the codebook against what I see as a hazard I find myself thinking I can out think the thinkers. I keep trying to learn, but I am somewhat dependent on those who have dug the trenches. I lean heavily on the expert?s opinions such as the NEC handbook, Mike Holts, McPortland, Don resqcapt?s and others. That was meant as a compliment!
The more components a circuit has the more complex it becomes. The hazard I see is if you lose the neutral at a service the more likely that appliances are going to get fried. The more a branch circuit looks like a feeder or a service the more at risk equipment becomes if the neutral is lost. I have seen lighting and appliances fry when a neutral is lost on a feeder. Some actually smoked heavily I could see this as a potential hazard in a building.
[ August 25, 2003, 06:26 PM: Message edited by: david ]
Don,
I have much respect for your opinion. And I see what you are saying.
There is nothing in the codebook that says you have to use a neutral. I think there are some things in the design of circuits that were considered basic. And the writers of the rules never imagined they would have to address every aspect of electrical design with thou shall not. I am not a Benjamin Franklin and if I weigh every rule in the codebook against what I see as a hazard I find myself thinking I can out think the thinkers. I keep trying to learn, but I am somewhat dependent on those who have dug the trenches. I lean heavily on the expert?s opinions such as the NEC handbook, Mike Holts, McPortland, Don resqcapt?s and others. That was meant as a compliment!
The more components a circuit has the more complex it becomes. The hazard I see is if you lose the neutral at a service the more likely that appliances are going to get fried. The more a branch circuit looks like a feeder or a service the more at risk equipment becomes if the neutral is lost. I have seen lighting and appliances fry when a neutral is lost on a feeder. Some actually smoked heavily I could see this as a potential hazard in a building.
[ August 25, 2003, 06:26 PM: Message edited by: david ]
- Location
- Illinois
- Occupation
- retired electrician
Re: BRANCH CIRCUIT
Steve,
Don
Steve,
I don't think that the code says that, and the 2005 code will actually be moving the other way. Many of the Chapter 3 xxx.10 sections (uses permitted)will be deleted leaving only the xxx.12(uses not permitted) sections for guidance. The general rule will be if it doesn't say that you can't do, then you can do it.
Don
Re: BRANCH CIRCUIT
All joking aside wouldn't this be the correct answer the way the original question was ask?
Question FOR SINGLE-PHASE,HOW MANY CIRCUITS CAN SHARE A NUETRAL FOR LIGHTING AND RECEPTACLE ONLY AND WHERE IS IT LOCATED IN THE CODE BOOK (ARTICAL).
A fourwire circuit with two hots a eq. grd and a neutral. Two circuits one from line one and one from line two per branch circuit.
Ronald:
All joking aside wouldn't this be the correct answer the way the original question was ask?
Question FOR SINGLE-PHASE,HOW MANY CIRCUITS CAN SHARE A NUETRAL FOR LIGHTING AND RECEPTACLE ONLY AND WHERE IS IT LOCATED IN THE CODE BOOK (ARTICAL).
A fourwire circuit with two hots a eq. grd and a neutral. Two circuits one from line one and one from line two per branch circuit.
Ronald:
Re: BRANCH CIRCUIT
In a perfectly balanced muti-wire branch circuit, single or three phase, you wouldn't need a grounded conductor. In otherwords remove it, you won't see a difference.
There is nothing code wise that says one properly sized neutral can't be used for all branch circuits.
If this is a true test question we may be in for another long thread.
Roger
In a perfectly balanced muti-wire branch circuit, single or three phase, you wouldn't need a grounded conductor. In otherwords remove it, you won't see a difference.
There is nothing code wise that says one properly sized neutral can't be used for all branch circuits.
If this is a true test question we may be in for another long thread.
Roger
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