Branch circuit definition

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cppoly

Senior Member
Location
New York
To help better understand a branch circuit, the NEC definition is: "The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s)"

The definition of an outlet is: "A point on the wiring system at which current is taken to supply utilization equipment."

So question: ALL in between the final OCPD and an outlet is a branch circuit?

For instance, a breaker supplies power to a lighting junction box. This lighting junction box contains both input power and data, which is then distributed to other junction boxes until at which point a lighting fixture whip connects to this final junction box. I would think everything is considered a branch circuit UNTIL the final junction box which provides the whip to the lighting fixture as opposed to the first lighting junction box right that distributes power and data further down the line?
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
I agree that the branch circuit does not end at the upstream junction box. I am less certain about the final junction box and the status of the whip, in part because it is not clear to my how this is built. If, for example, the final junction box is attached to the ceiling structure, and the light fixture screws onto that same junction box, then I would say that the branch circuit ends at that junction box, and that the whip is a component of the light fixture (i.e., not a part of the branch circuit). Derek, are you seeing this differently?
 

jumper

Senior Member
I agree that the branch circuit does not end at the upstream junction box. I am less certain about the final junction box and the status of the whip, in part because it is not clear to my how this is built. If, for example, the final junction box is attached to the ceiling structure, and the light fixture screws onto that same junction box, then I would say that the branch circuit ends at that junction box, and that the whip is a component of the light fixture (i.e., not a part of the branch circuit). Derek, are you seeing this differently?

Yes to the first part and partly no to the second. I would not consider a whip part of a fixture as it is nothing more than a piece of flexible metallic cable that connects the fixture to the junction box. That makes it part of the branch circuit IMO.

If a fixture directly attaches to a junction box then there is no whip. The ballast leads would connect straight to the branch circuit conductors and again no whip involved.
 

iwire

Moderator
Staff member
Location
Massachusetts
Sorry D man I see it like Charlie, the outlet is where the fixture whip ties into the branch circuit.

Check this out

240.5 Protection of Flexible Cords, Flexible Cables, and
Fixture Wires.

(B) Branch-Circuit Overcurrent Device. Flexible cord
shall be protected, where supplied by a branch circuit, in accordance
with one of the methods described in 240.5(B)(1),
(B)(3), or (B)(4). Fixture wire shall be protected, where supplied
by a branch circuit,
in accordance with 240.5(B)(2).
 

iwire

Moderator
Staff member
Location
Massachusetts
I see your point. I was talking about MC or AC whips to fixtures. All that stuff is article 400 stuff.

OK, yes, if the whip is field installed AC, MC, NM etc with conductor sizes to match the over current protection device I agree with you.

When I here fixture whip I think small conductors.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
OK, yes, if the whip is field installed AC, MC, NM etc with conductor sizes to match the over current protection device I agree with you.

When I hear fixture whip I think small conductors.

And that is the important distinction (emphasized in red).

A comparable situation is a residential oven that has a manufacturer assembled flex whip already attached. The field electrician terminates this whip at a junction box which is on the end of the branch circuit originating at the final overcurrent protective device. The junction box, in this case is the Outlet, point on the Wiring System at which current is taken.

However, if the residential oven has no manufacturer assembled and attached whip, and the field electrician attaches a field assembled whip, then the Outlet is in the splice compartment of the Oven.
 

cppoly

Senior Member
Location
New York
I attached a sketch to help explain my question. The yellow is what I believe is a branch circuit and the orange is what I believe is not part of the branch circuit. Do you agree?
 

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iwire

Moderator
Staff member
Location
Massachusetts
I attached a sketch to help explain my question. The yellow is what I believe is a branch circuit and the orange is what I believe is not part of the branch circuit. Do you agree?

It depends on the specifics of the sections you have labeled as whips
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
I attached a sketch to help explain my question. The yellow is what I believe is a branch circuit and the orange is what I believe is not part of the branch circuit. Do you agree?

OK. To apply the definitions from Article 100, and answer your question, you have to supply more information.

In your diagram, the portion of "the circuit" (not a Code defined term) that you have highlighted. . . who makes it? Does field electrician make it? Is it a part that must be supplied pre-assembled by the luminaire manufacturer, a whip that can only be used with the installed luminaire?
 

cppoly

Senior Member
Location
New York
Whip from the lighting fixture is 3 feet (as shown in orange). I might not be saying it correctly but it's the cord provided by the manufacturer that is hard wired to the last junction box.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Whip from the lighting fixture is 3 feet (as shown in orange). I might not be saying it correctly but it's the cord provided by the manufacturer that is hard wired to the last junction box.

OK. It seems that you are saying, "The Luminaire comes from the manufacturer with a pre-assembled and attached whip." Correct?

In that case, the loose end of the whip that attaches to the wires in the junction box form "The Outlet".
 

kwired

Electron manager
Location
NE Nebraska
Tap conductors to a luminaire or to a wall mounted oven are permitted and are still part of the branch circuit I believe.

The branch circuit ends at the outlet - which that location is what may be more debatable.
 

iwire

Moderator
Staff member
Location
Massachusetts
Tap conductors to a luminaire or to a wall mounted oven are permitted and are still part of the branch circuit I believe.

The branch circuit ends at the outlet - which that location is what may be more debatable.

A factory installed /provided whip is not part of the branch circuit
 

kwired

Electron manager
Location
NE Nebraska
A factory installed /provided whip is not part of the branch circuit
On the oven I might agree those are almost always factory installed and even use higher temp conductors that ordinarily wouldn't be commonly used as premises wiring, not sure if I fully agree on a luminaire though.

You can often order a luminaire with or without whip, now field install a whip, identical or even just nearly identical to what would be factory installed - which is it? Part of the luminaire or extension of the branch circuit?
 
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