paul hodge
Member
- Location
- atl
What is the defining line between a feeder and a branch circuit?
what defines a FEEDER from BRANCH CIRCUIT
- Thread starter paul hodge
- Start date
- Status
- Location
- Massachusetts
Branch Circuit. The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).
Feeder. All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.
Feeder. All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
And for the thread-busting question, does an OCPD (such as an AC disco) at the end of a branch circuit change that circuit into a feeder?
(I say no.)
(I say no.)
- Location
- Massachusetts
LarryFine said:
I give a conditional no.
It depends on the situation.
And for the thread-busting question, does an OCPD (such as an AC disco) at the end of a branch circuit change that circuit into a feeder?
From the definition of Supplementary Overcurrent Protective Device I believe clears up any argument.
Last sentence adds clarification This limited protection is in addition to the protection provided in the required branch circuit overcurrent protective device.
I go with no.
From the definition of Supplementary Overcurrent Protective Device I believe clears up any argument.
Last sentence adds clarification This limited protection is in addition to the protection provided in the required branch circuit overcurrent protective device.
I go with no.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
If an individual chooses, for whatever reason, to install a disco with fuses or a circuit breaker at the location of the AC unit, then the conductors between the panel and the fused disco are feeders. I do not see any reason why it would impact the installation other than being a technicality.
The example used as supplementary overcurrent devices is incorrect. A supplementary device is not designed the same as a standard overcurrent device. Take a look at some of the websites that provide this info.
The example used as supplementary overcurrent devices is incorrect. A supplementary device is not designed the same as a standard overcurrent device. Take a look at some of the websites that provide this info.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Are you sure?Pierre C Belarge said:
The NEC refers to this overcurrent protection existing at the end of a branch circuit.
After a quick google search, top on the list was this PDF from Mark Ode on the topic. He describes field-installed OCPDs in light poles in his example.
What is your defining point for deciding to call something a feeder or a BC? I'm not quite sure what mine is yet.
Agreed.
Do you have one in particular in mind?
- Location
- Illinois
- Occupation
- retired electrician
Pierre,
Don
It is a huge impact if the conductors to the fused AC disconnect are feeders, because if they are feeders they have to sized to the rating of the feeder OCPD. If they are branch circuits they are sized to the minimum circuit size shown on the nameplate and the branch OCPD can be sized per the maximum OCPD shown on the name plate. In many cases, if the conductors are feeders, they would have to be two sizes larger than if they are branch circuit conductors. It is my opinion that the fused disconnect at the AC unit is not the branch circuit OCPD.
Don
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Don
You are correct, and I neglected 240.4(G) in my haste to answer. Thanks for the pick up.
George
Look a little further down in the link you provided "google
'. You will see some more info on the "supplementary device" topic.
You are correct, and I neglected 240.4(G) in my haste to answer. Thanks for the pick up.
George
Look a little further down in the link you provided "google
'. You will see some more info on the "supplementary device" topic.
DaveTap
Senior Member
- Location
- Currently Flowery Branch, GA
Okay... then what about machines that have their own overcurrent devices built in? Everything to the machine is a feeder?
How about a 15A outlet strips with built in breaker? Does it change the circuit just by plugging into it? What if its plugged into a 20A circuit? Hmm...
How about a 15A outlet strips with built in breaker? Does it change the circuit just by plugging into it? What if its plugged into a 20A circuit? Hmm...
DaveTap
Senior Member
- Location
- Currently Flowery Branch, GA
Oops walked away for too long before posting
Last sentence adds clarification... That it's still a branch circuit was the point.
Motor protection was the first thing that came to mind.
Lots of issues are involved if the circuit becomes a feeder, rather than a branch circuit. If the committees are going to take the language structure that way, it's going to get read, and interpetted or miss-interpetted that way, let's fix the verbage now.
Don't need someone explaining that "Ya we all know what it was trying to say, but this is what it realy means...". Words and structure of sentence, or paragraph, need to be where we can all be on the same page.
Not saying I was wrong, just mis-interpetted and refuse to take the crow for lunch on this.
Motor protection was the first thing that came to mind.
Lots of issues are involved if the circuit becomes a feeder, rather than a branch circuit. If the committees are going to take the language structure that way, it's going to get read, and interpetted or miss-interpetted that way, let's fix the verbage now.
Don't need someone explaining that "Ya we all know what it was trying to say, but this is what it realy means...". Words and structure of sentence, or paragraph, need to be where we can all be on the same page.
Not saying I was wrong, just mis-interpetted and refuse to take the crow for lunch on this.
milwaukeesteve
Senior Member
- Location
- Milwaukee, WI
I just got referred to this thread, because I just started one similar to this but never saw this one before.
(If I could merge the 2 I would, but don't now how if I could)
Here's is my new thread, dealing with sizing of that originating OCPD
My question is .... 'huh???'
I think I am lost.
First....
Very Nice. Right to the point.
Then...
Doesn't your question state exactly what is required in Bob's definition of a Feeder: OCPD (such as an AC Disco)... end of Branch Circuit???
Then Bob replies with a conditional no.
Then Larry states no, because of the 'required' in the definition of a 'supplimental'
So what is the answer, because it sounds like 'no' is your consensus, but the arguement isn't making sense to me?
The definition of Supplimentary Overcurrent Protective Device is INDENDED toprovide LIMITED OCP for specific apps...
This is and isn't what we are talking about with the original thread. This would be if there were fuses installed at the unit to protect the unit that is more specific to the load than the originating and REQUIRED Branch Circuit OCPD. FOR EXAMPLE: If you feed a walk in cooler equipment with one circuit, a 30 Amp 240V circuit, and for the Condensor above, you install a 20Amp fused disconnect, and a 15Amp fused disconnect to feed the evaporator fan(disconnect would still be needed within sight). These OCPDs would be SPECIFIC and LIMITING as defined by Art 100.
I believe that the answer to Larry's Threadbusting question is YES. Because, again, Art 100 states that Feeders between the source and the FINAL OCPD, which is what an AC disco is. (fused AC disco for clarification)
(If I could merge the 2 I would, but don't now how if I could)
Here's is my new thread, dealing with sizing of that originating OCPD
My question is .... 'huh???'
I think I am lost.
First....
Very Nice. Right to the point.
Then...
Doesn't your question state exactly what is required in Bob's definition of a Feeder: OCPD (such as an AC Disco)... end of Branch Circuit???
Then Bob replies with a conditional no.
Then Larry states no, because of the 'required' in the definition of a 'supplimental'
So what is the answer, because it sounds like 'no' is your consensus, but the arguement isn't making sense to me?
The definition of Supplimentary Overcurrent Protective Device is INDENDED toprovide LIMITED OCP for specific apps...
This is and isn't what we are talking about with the original thread. This would be if there were fuses installed at the unit to protect the unit that is more specific to the load than the originating and REQUIRED Branch Circuit OCPD. FOR EXAMPLE: If you feed a walk in cooler equipment with one circuit, a 30 Amp 240V circuit, and for the Condensor above, you install a 20Amp fused disconnect, and a 15Amp fused disconnect to feed the evaporator fan(disconnect would still be needed within sight). These OCPDs would be SPECIFIC and LIMITING as defined by Art 100.
I believe that the answer to Larry's Threadbusting question is YES. Because, again, Art 100 states that Feeders between the source and the FINAL OCPD, which is what an AC disco is. (fused AC disco for clarification)
Last edited:
milwaukeesteve
Senior Member
- Location
- Milwaukee, WI
<<<<<HERE IS THE QUESTION I ASKED IN THE OTHER THREAD, copied and pasted>>>>>
If I have a HACR load, with a fused disconnect, what size OCPD and Short Circuit Protection do I install for the circuit feeder conductors that feed the fused disconnect.
Example:
I have a A/C unit outside
max fuse size 40AMPs
Min circuit Ampacity 19Amps
Fused disconnect with 40AMP Time Delay Fuses
Conductors from disconnect to A/C unit are #12s
The above is legal as is from disconnect to unit.
Now my question is the 'feeders' that feed the disconnect. IF they are from a source that cannot have HACR rating (ie. Zinsco, FPE, Pushmatic), what size breaker do you need, what size can you install, what size conductors minimum?
If the Minimum circuit ampacity is 19 Amps, the conductors should never see a running load of more than 19Amps (here we are not worried about in rush current at startup). We should be able to keep #12s as our conductors.
What size breaker (Non inverse time breaker) is needed to allow for inrush current at startup? If I focus on the conductors and only install 20 Amp breakers, the breaker will trip. Am I allowed to install a 30, 40 or even a 100 Amp breaker supplying the 'feeder' conductors, since the Fuses protect the conductors on Overcurrent?
Is it fine to install a 30, 40 or 100Amp Breaker? Now what size conductors? Again I say only #12s.
Any thoughts?
Editted with additional thought: I don't know if any of those breaker manufactures listed above do make HACR rated breakers. I have never seen one. If so, please let me know, too. There may be more also, those were off the top of my head.
If I have a HACR load, with a fused disconnect, what size OCPD and Short Circuit Protection do I install for the circuit feeder conductors that feed the fused disconnect.
Example:
I have a A/C unit outside
max fuse size 40AMPs
Min circuit Ampacity 19Amps
Fused disconnect with 40AMP Time Delay Fuses
Conductors from disconnect to A/C unit are #12s
The above is legal as is from disconnect to unit.
Now my question is the 'feeders' that feed the disconnect. IF they are from a source that cannot have HACR rating (ie. Zinsco, FPE, Pushmatic), what size breaker do you need, what size can you install, what size conductors minimum?
If the Minimum circuit ampacity is 19 Amps, the conductors should never see a running load of more than 19Amps (here we are not worried about in rush current at startup). We should be able to keep #12s as our conductors.
What size breaker (Non inverse time breaker) is needed to allow for inrush current at startup? If I focus on the conductors and only install 20 Amp breakers, the breaker will trip. Am I allowed to install a 30, 40 or even a 100 Amp breaker supplying the 'feeder' conductors, since the Fuses protect the conductors on Overcurrent?
Is it fine to install a 30, 40 or 100Amp Breaker? Now what size conductors? Again I say only #12s.
Any thoughts?
Editted with additional thought: I don't know if any of those breaker manufactures listed above do make HACR rated breakers. I have never seen one. If so, please let me know, too. There may be more also, those were off the top of my head.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Branch OCPDs are tested to UL 489. Branch devices can protect "external" circuit conductors. They carry a UL Listing and can be used in stand alone situations. Supplementary OCPDs are tested to UL 1447. Supplementary devices only protect "internal" conductors. They carry a UL recognition and can only be used as a component.
Some differences are:
Overload test - UL 489 = 6x, UL 1077= 1.5x
Short circuit - UL 489 = 5kA MIN for 2 ops and still function, UL 1077 = 5kA MAX for 3 ops and can become inoperable
So a fused disconnect mounted external to the A/C unit is never a supplementary OCPD, but one mounted internal to it may be.
Some differences are:
Overload test - UL 489 = 6x, UL 1077= 1.5x
Short circuit - UL 489 = 5kA MIN for 2 ops and still function, UL 1077 = 5kA MAX for 3 ops and can become inoperable
So a fused disconnect mounted external to the A/C unit is never a supplementary OCPD, but one mounted internal to it may be.
- Location
- Illinois
- Occupation
- retired electrician
I don't think that the question really hinges on "supplementary" or not. If the purpose of the fuses at the fused disconnect are to protect the AC, then the wires on the line side of the fused disconnect are branch circuit conductors, but if the purpose is to protect the conductors on the load side of the fused disconnect, then the supply conductors become feeders and have to be sized based on the rating of the feeder OCPD.
Don
Don
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Along Dons comment "It is my opinion that the fused disconnect at the AC unit is not the branch circuit OCPD."
If the fused disco was a feeder then it would require a grounding electrode system, if it was outside the building, and I have not seen that done.
Its a maintenance disconnect or supplemental OCD. In fact, regarding light poles, there was a code change a few years ago to clarify that light poles are not buildings and don't require disconnects. See 225.32 Ex 3
If the fused disco was a feeder then it would require a grounding electrode system, if it was outside the building, and I have not seen that done.
Its a maintenance disconnect or supplemental OCD. In fact, regarding light poles, there was a code change a few years ago to clarify that light poles are not buildings and don't require disconnects. See 225.32 Ex 3
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
tom baker said:
There is no requirement in Article 215 for a "grounding electrode system" just because the circuit is a feeder that is outdoors. Of course, if the device is also a "building disconnect" then other NEC articles may be applicable.
There is a difference between a specific Supplementary Overcurrent Protective Device (article 100) and the function of supplemental overcurrent protection (article 240.10)
- Location
- Massachusetts
jim dungar said:
Any feeder that runs to a seperate structure must have a GES
225.30 if I remember correctly
- Location
- Illinois
- Occupation
- retired electrician
Jim,
Don
Yes, but a seperate "structure" does require a grounding electrode system, and per the NEC just about everything is a structure. If the conductors serving the structure are branch circuit conductors, then the exception to 250.32(A) says you do not need the grounding electrode sytem. If the conductors are feeder conductors, then you do.
Don
- Status