Definition of Feeder

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petersonra

Senior Member
Location
Northern illinois
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engineer
Yes but the proposal has an exception when there is an overcurrent protective device in between the load center and a piece of equipment only then I want that normally called feeder to be called a branch circuit. Thus the entire run between a panel and a single piece of equipment is a branch circuit whether there is a disconnect with overcurrent protective device in it or not

what is the benefit of doing so?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
what is the benefit of doing so?


I believe here is the issue. 430.62 speaks of feeder for fixed motor load(s). This states that a feeder should be based on the largest overcurrent protective device for a motor plus the sum of other motors. We have only one motor so a 3 phase 20 hp motor @ 208 volts is 59.4 amps. Table 430.52 tells us to take 250% of the load for a polyphase inverse time breaker-- 148.5 amps

This means the feeder technically should be 148.5 amps instead of a conductor size for the branch circuit at 125% 74.25 amps



430.62 Rating or Setting — Motor Load.
(A) Specific Load. A feeder supplying a specific fixed motor
load(s) and consisting of conductor sizes based on 430.24 shall
be provided with a protective device having a rating or setting
not greater than the largest rating or setting of the branch circuit
short-circuit and ground-fault protective device for any
motor supplied by the feeder [based on the maximum permitted
value for the specific type of a protective device in accordance
with 430.52, or 440.22(A) for hermetic refrigerant motorcompressors],
plus the sum of the full-load currents of the
other motors of the group
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
430.62 only allows you to increase the size of the feeder OCPD above what the ampacity of the feeder conductors might otherwise limit you to. It is not the minimum rating of the feeder OCPD.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
430.62 only allows you to increase the size of the feeder OCPD above what the ampacity of the feeder conductors might otherwise limit you to. It is not the minimum rating of the feeder OCPD.


I believe it is--- read it again it states the max size of the short circuit , ground fault protective device
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I believe it is--- read it again it states the max size of the short circuit , ground fault protective device

430.62 Rating or Setting — Motor Load.
(A) Specific Load. A feeder supplying a specific fixed motor
load(s) and consisting of conductor sizes based on 430.24 shall
be provided with a protective device having a rating or setting
not greater than the largest rating or setting of the branch circuit
short-circuit and ground-fault protective device for any
motor supplied by the feeder [based on the maximum permitted
value for the specific type of a protective device in accordance
with 430.52, or 440.22(A) for hermetic refrigerant motorcompressors],
plus the sum of the full-load currents of the
other motors of the group

It does not seem to say what you think it says. "Not greater than" means a maximum upper limit is set, but it does not affect how low the rating can go.

All the "maximum permitted value" language does is allow you to apply the maximum allowed rating to the calculation as opposed to the rating of the actual OCPD used. It does not set a floor, but a ceiling.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
430.62 regulates "Part V. Motor Feeder Short-Circuit and Ground-Fault Protection."

430.62 directs you to 430.24 to size the conductors. That's in Part II.
If the wire between the panel and the disconnect is a feeder then that wire must be sized to the overcurrent protective device....NO? The branch circuit is sized per the motor
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
If the wire between the panel and the disconnect is a feeder then that wire must be sized to the overcurrent protective device....NO? The branch circuit is sized per the motor

Look at Article 215.3 Overcurrent Protection, which sends you to Part I of Article 240 and specifically to 240.3 which lands one in Table 240.3.

So, NO, the wire is not required to be sized to the OCPD in 430.62 because 430.62 sends you to 430.24 to size the wire of a Feeder.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I see that now that the overcurrent protective device must be sized as 430.62 but the feeder conductors are not sized that way and obviously, can be smaller than the overcurrent protective device.

I wish I can find that thread.

Okay so it is still awkward in that the overcurrent protective device for the feeder would be sized higher than the overcurrent protective device of the branch circuit when they are really the same in terms of what's happening current wise.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
The branch circuit overcurrent protective device is usually size at 175% and on most units today the max overcurrent protective device is lower than that. Is this making sense. I think this was the jist of the old thread.. my memory stinks
 

kwired

Electron manager
Location
NE Nebraska
I think existing feeder definition is fine, if anything to get what Dennis wants to accomplish done a modification may be needed to the branch circuit definition.

Otherwise you have service conductors and branch circuit conductors, and everything else is a feeder or a feeder tap.

I don't get it... Any feeder is from either a service or the sub panel as it stands now. Why does my words change that... The definition does not affect the wires between the service and a subpanel-- those are still feeders-- it only changes when it feeds an individual piece of equipment
If I missed something in the posts since here I apologize, quite a few and I didn't read them that carefully. As it is now a feeder is pretty much everything that isn't a branch circuit or service equipment related. Secondary of a separately derived system - feeder, unless maybe it only feeds a single load. On site source that isn't supplying a single utilization equipment - feeder.

Services supply feeders, feeders supply branch circuits. About the only time a service supplies a branch circuit is when the service is supplying a single load. Feeders can supply additional feeders or feeder taps though.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
If I missed something in the posts since here I apologize, quite a few and I didn't read them that carefully. As it is now a feeder is pretty much everything that isn't a branch circuit or service equipment related. Secondary of a separately derived system - feeder, unless maybe it only feeds a single load. On site source that isn't supplying a single utilization equipment - feeder.

Services supply feeders, feeders supply branch circuits. About the only time a service supplies a branch circuit is when the service is supplying a single load. Feeders can supply additional feeders or feeder taps though.


Nobody is questioning what a feeder is as defined in the NEC. I just want the conductors between a power supply and an individual piece of equipment to be considered a branch circuit even when the disconnect has an overcurrent protective device. It makes no sence to define one part a feeder and another part of the circuit as a branch circuit.

Technically the feeder would be required to have an overcurrent protective device larger than the branch circuit overcurrent protective device. Not a big deal as such since I don't believe anyone sizes the overcurrent protective device to the fused disconnect as a feeder when one unit or piece of equipment is involved but technically the code requires it and someone could enforce a larger overcurrent protective device. This can cost mucho dollars unnecesasarily.

A/C units often are sized at much lower than the 175% that the units used to be sized at. Look at the max overcurrent protective device on a unit and see.. I have seen some where the max was not much different then the min size conductor-- 125%. Now make the ec size the overcurrent protective device for a unit at 250% min. for a feeder and then coukd be a lot more money unnecessarily
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Maybe this is too oblique, but you could try:

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. For the purposes of this definition, extra overcurrent devices which are installed but not required by this code shall not be considered.(CMP-2)

Reasoning: your complaint is that someone uses a fused disconnect where only an unfused disconnecting means is required (or perhaps even the disco was not required). The fact that the overcurrent device was put in when it wasn't required shouldn't change the rules for how the upstream conductors are installed. This language addresses that directly.

The downside to this approach is that it is overly broad and could perhaps create confusion or some loophole in some other type of case that doesn't readily come to mind.
 

kwired

Electron manager
Location
NE Nebraska
Nobody is questioning what a feeder is as defined in the NEC. I just want the conductors between a power supply and an individual piece of equipment to be considered a branch circuit even when the disconnect has an overcurrent protective device. It makes no sence to define one part a feeder and another part of the circuit as a branch circuit.

Technically the feeder would be required to have an overcurrent protective device larger than the branch circuit overcurrent protective device. Not a big deal as such since I don't believe anyone sizes the overcurrent protective device to the fused disconnect as a feeder when one unit or piece of equipment is involved but technically the code requires it and someone could enforce a larger overcurrent protective device. This can cost mucho dollars unnecesasarily.

A/C units often are sized at much lower than the 175% that the units used to be sized at. Look at the max overcurrent protective device on a unit and see.. I have seen some where the max was not much different then the min size conductor-- 125%. Now make the ec size the overcurrent protective device for a unit at 250% min. for a feeder and then coukd be a lot more money unnecessarily
I'm not aware of any requirement that a feeder needs to have higher overcurrent setting then a branch circuit it supplies.

I have many times run a motor circuit with breaker at a load center and same size breaker as disconnect near the motor. Technically that makes the first part of the circuit a feeder and the second part a branch circuit, but doesn't ordinarily change anything else you do for the installation, because of that it sort of doesn't matter (at least to me) if your proposal would be accepted or not as I don't really see it changing what gets installed, just what we call it.
 
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