feeders, services, and branch circuits
- Thread starter jls11772
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sandsnow
Senior Member
- Location
- Southern California
Re: feeders, services, and branch circuits
Have you used the definitions in Art. 100?
Have you used the definitions in Art. 100?
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: feeders, services, and branch circuits
The current and voltage ratings have nothing to do with this question. Here is a simple, though not complete and not completely accurate explanation: A "service" comes from the utility. A "feeder" provides power to some other distribution component (e.g., to a sub-panel). A "branch circuit" provides power to a load.
That's not complete because an on-site backup generator could qualify as a "service." Also, a "branch circuit" could provide power to more than one load. But if a wire provides power to more than one load, and it does so by first providing power to some enclosure that contains fuses, switches, or breakers, then that wire is a "feeder," and not a "branch circuit."
The current and voltage ratings have nothing to do with this question. Here is a simple, though not complete and not completely accurate explanation: A "service" comes from the utility. A "feeder" provides power to some other distribution component (e.g., to a sub-panel). A "branch circuit" provides power to a load.
That's not complete because an on-site backup generator could qualify as a "service." Also, a "branch circuit" could provide power to more than one load. But if a wire provides power to more than one load, and it does so by first providing power to some enclosure that contains fuses, switches, or breakers, then that wire is a "feeder," and not a "branch circuit."
bphgravity
Senior Member
- Location
- Florida
Re: feeders, services, and branch circuits
Draw a picture and insert all the names and defintions of the various components from the service point all the way to the outlets. You can even insert some code requirements throughout the diagram.
Draw a picture and insert all the names and defintions of the various components from the service point all the way to the outlets. You can even insert some code requirements throughout the diagram.
pierre
Senior Member
- Location
- Westchester County, New York
Re: feeders, services, and branch circuits
That's not complete because an on-site backup generator could qualify as a "service."
You might want to review the NEC definition of service and think about what you wrote here. Where is the generator originating from?
The people in our industry understand concepts much better through the use of illustrations and pictures (especially in color). As Bryan has mentioned, use several pictures and illustrations that you can have as handouts for the present and future classes to help them visually and then conceptually understand the different types of conductors (Service, Feeder, and Branch circuit).
That's not complete because an on-site backup generator could qualify as a "service."
You might want to review the NEC definition of service and think about what you wrote here. Where is the generator originating from?
The people in our industry understand concepts much better through the use of illustrations and pictures (especially in color). As Bryan has mentioned, use several pictures and illustrations that you can have as handouts for the present and future classes to help them visually and then conceptually understand the different types of conductors (Service, Feeder, and Branch circuit).
sandsnow
Senior Member
- Location
- Southern California
Re: feeders, services, and branch circuits
Only if the generator is owned by the utility, right????
If not, then it is an SDS and then feeder source or just a source for another feeder.
Only if the generator is owned by the utility, right????
If not, then it is an SDS and then feeder source or just a source for another feeder.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: feeders, services, and branch circuits
OK. I withdraw the bit about a backup generator comprising a service. Mea culpa.
OK. I withdraw the bit about a backup generator comprising a service. Mea culpa.
jwelectric
Senior Member
- Location
- North Carolina
Re: feeders, services, and branch circuits
SE conductors have one OCPD on the load side and terminate at the main.
Feeders have two OCPDs one at both ends of the conductor.
Branch circuits have one OCPD at the beginning of the circuit.
Short sweet and easy.
SE conductors have one OCPD on the load side and terminate at the main.
Feeders have two OCPDs one at both ends of the conductor.
Branch circuits have one OCPD at the beginning of the circuit.
Short sweet and easy.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: feeders, services, and branch circuits
Except that a feeder from the main panel to an MLO panel only has an OCPD at one end.
- Location
- Logan, Utah
Re: feeders, services, and branch circuits
Wouldn't a feeder from a main panel to a MLO panel end in multiple OCPDs at the sub panel?
Chris
Wouldn't a feeder from a main panel to a MLO panel end in multiple OCPDs at the sub panel?
Chris
jwelectric
Senior Member
- Location
- North Carolina
Re: feeders, services, and branch circuits
DittoOriginally posted by raider1:
Wouldn't a feeder from a main panel to a MLO panel end in multiple OCPDs at the sub panel?
Chris
sandsnow
Senior Member
- Location
- Southern California
Re: feeders, services, and branch circuits
We could do this all day. Even a branch circuit could have an OCPD at it's load end. Interanl fuses inside a heat pump. 12kV services conductors have OCPD at each end.
Although I didn't include using diagrams with my 1st post, I think the Def's in Art 100 should be the only thing used to define these terms. Using diagrams would of course be helpful. I should have mentioned that.
I think this is one case where the NEC defines it well. The analogies presented here are good, however, the definitions in the NEC should alsways be the starting and ending point to the discussion.
Getting the students to understand things where defined in the NEC is crucial to a sound basis in our field. Once we get past theory, the NEC is the basis for all we do, well except for productivity, ethics, etc.
I hear so many terms like "mechanical ground". There's no such thing.
Ok, I'll get off my soapbox.
We could do this all day. Even a branch circuit could have an OCPD at it's load end. Interanl fuses inside a heat pump. 12kV services conductors have OCPD at each end.
Although I didn't include using diagrams with my 1st post, I think the Def's in Art 100 should be the only thing used to define these terms. Using diagrams would of course be helpful. I should have mentioned that.
I think this is one case where the NEC defines it well. The analogies presented here are good, however, the definitions in the NEC should alsways be the starting and ending point to the discussion.
Getting the students to understand things where defined in the NEC is crucial to a sound basis in our field. Once we get past theory, the NEC is the basis for all we do, well except for productivity, ethics, etc.
I hear so many terms like "mechanical ground". There's no such thing.
Ok, I'll get off my soapbox.
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: feeders, services, and branch circuits
You think I wasn't anticipating the possibility that someone would try to make that point?
jwelectric
Senior Member
- Location
- North Carolina
Re: feeders, services, and branch circuits
To be a feeder it will need to have OCP for the feeder conductors and terminate in an enclosure that has OCP weather it is a single OCP or a main lug panel. There will still be OCP on both ends of the conductor.
A branch circuit supplying current to a piece of equipment with or with out supplementary OCP is still a branch circuit. The key to a piece of equipment that contains OCP that was shipped with it is these OCP devices have no bearing on the service, feeders or the branch circuit. In essence they don?t exist.
To be a feeder it will need to have OCP for the feeder conductors and terminate in an enclosure that has OCP weather it is a single OCP or a main lug panel. There will still be OCP on both ends of the conductor.
A branch circuit supplying current to a piece of equipment with or with out supplementary OCP is still a branch circuit. The key to a piece of equipment that contains OCP that was shipped with it is these OCP devices have no bearing on the service, feeders or the branch circuit. In essence they don?t exist.
stevearne
Senior Member
- Location
- Rapid City, SD
Re: feeders, services, and branch circuits
It has been mentioned already in this discussion, be sure to stick with the NEC definitions. There is no service conductor unless there is a utility service point, as the service conductor is from the service point to the service disconnecing means.
The feeder is from service equipment or other source such as separately derived system to the final branch circuit protection device.
Branch circuit is between the final device protecting the circuit (not counting supplemental protection) and the outlet(s).
I like to give the class an illustration by telling them to visualize the circuit to the outdoor air conditioner unit. If the disconnect by the unit is nonfusible, the last overcurrent device is the breaker in the panel, so the conductors from the panel to the outdoor unit are branch circuit conductors. Change the nonfusible disconnect to a fusible disconnect, and the conductors from the breaker in the panel to the disconnect become feeder conductors, and the conductors from the outdoor disconnect to the unit are the brach circuit conductors.
There are some very good diagrams in the Understanding the NEC volume 1 that shows these 3 conductor types in an installation.
It has been mentioned already in this discussion, be sure to stick with the NEC definitions. There is no service conductor unless there is a utility service point, as the service conductor is from the service point to the service disconnecing means.
The feeder is from service equipment or other source such as separately derived system to the final branch circuit protection device.
Branch circuit is between the final device protecting the circuit (not counting supplemental protection) and the outlet(s).
I like to give the class an illustration by telling them to visualize the circuit to the outdoor air conditioner unit. If the disconnect by the unit is nonfusible, the last overcurrent device is the breaker in the panel, so the conductors from the panel to the outdoor unit are branch circuit conductors. Change the nonfusible disconnect to a fusible disconnect, and the conductors from the breaker in the panel to the disconnect become feeder conductors, and the conductors from the outdoor disconnect to the unit are the brach circuit conductors.
There are some very good diagrams in the Understanding the NEC volume 1 that shows these 3 conductor types in an installation.
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