Subfeed panel

[dburney]

I have a 120/208 225 amp panel. They are sub feeding a 100 amp panel with a main about 500 feet away off a 150 amp breaker in the 225 amp panel and useing #1 copper for the sub feed.
My question with this is it legal by NEC code to Feed it this way being it's feeding a 100 amp breaker or do they need to up size the wire to 1/0 and where in the NEC can I find the code violations if their are any

 

[Fitzdrew516]

NEC doesn't dictate voltage drop, but some energy codes do. However, it is good practice to have 2% or less drop on feeders and 3% or less on branch circuits. But to answer the question yes it is legal to feed a 100A mcb panel with a 150A breaker, but the wire would need to be sized for the 150A breaker.

 

[charlie b]

Using a 150 amp breaker to feed power through a #1 AWG wire is a violation of 240.4. We are required to protect wires at their ampacity, and the ampacity of a #1 is only 130 amps.

In addition, we are required to protect panelboards at their rating. You can use a feeder breaker in the 225 amp panel as that protection. But it has to be a 100 amp breaker. This issue goes away if the 100 amp panel has its own 100 amp main breaker. Reference: 408.36.

 

[Smart $]

It may be compliant under the tap rules. See 240.21(B)(5).

 

[cpinetree]

It may be compliant under the tap rules. See 240.21(B)(5).

:thumbsup:

 

[dburney]

Their is a 100 amp main in the sub panel and I will check the tap rule but not sure if the tap rule applies to feeders for a sub panel but I think it is currect that the wire needs to be sized for the 150 or change the breaker to a 125 to meet the wire size

 

[charlie b]

It may be compliant under the tap rules. See 240.21(B)(5).

I think not. A feeder directly connected to a feeder breaker does not meet the definition of "tap conductor." This requires some close reading and a high degree of just believing anything I say. :happyyes: But here it is anyway: A tap conductor is defined as one that has overcurrent protection ahead of its point of supply in excess of the conductor's ampacity. In this installation, the conductor has overcurrent protection "AT" its point of supply, not "AHEAD OF" its point of supply. So it's not a tap. QED.

 

[don_resqcapt19]

Using a 150 amp breaker to feed power through a #1 AWG wire is a violation of 240.4. We are required to protect wires at their ampacity, and the ampacity of a #1 is only 130 amps.
...

240.4(B) permits the #1s to be protected by the 150 amp breaker in this application.

 

[don_resqcapt19]

I think not. A feeder directly connected to a feeder breaker does not meet the definition of "tap conductor." This requires some close reading and a high degree of just believing anything I say. :happyyes: But here it is anyway: A tap conductor is defined as one that has overcurrent protection ahead of its point of supply in excess of the conductor's ampacity. In this installation, the conductor has overcurrent protection "AT" its point of supply, not "AHEAD OF" its point of supply. So it's not a tap. QED.

I had a code proposal to make it clear that a tap could originate at the load terminals of an OCPD. It was rejected with a panel comment that no change is required as the code already permits that.

10-45 Log #4825 NEC-P10
Final Action: Reject
(240.21(B))
_______________________________________________________________
Submitter: Don Ganiere, Ottawa, IL
Recommendation: Add text to read as follows:
(B) Feeder Taps. Conductors shall be permitted to betapped, without overcurrent protection at the tap, to a feeder as specified in240.21(B)(1) through (B)(5). Feeder taps shall be permitted to originate at theload terminal of an overcurrent protective device. The provisions of 240.4(B)shall not be permitted for tap conductors.
Substantiation: This type of installation ispermitted in many areas, but the code does not specifically permit it. Theadditional wording will make it clear that this is a code compliantinstallation. As long as all of the conditions of this section are compliedwith the point of origination of the tap conductor does not create anyadditional hazard.
Panel Meeting Action: Reject
Panel Statement: The proposed language is not necessaryas the present language permits such installation where appropriate.
Number Eligible to Vote: 12
BallotResults: Affirmative:12

blue=proposed new text

 

[jap]

I think not. A feeder directly connected to a feeder breaker does not meet the definition of "tap conductor." This requires some close reading and a high degree of just believing anything I say. :happyyes: But here it is anyway: A tap conductor is defined as one that has overcurrent protection ahead of its point of supply in excess of the conductor's ampacity. In this installation, the conductor has overcurrent protection "AT" its point of supply, not "AHEAD OF" its point of supply. So it's not a tap. QED.

To me as far as a "Tap" regardless of whether its breaker lugs or another piece of wire your terminating to,,, in both instances,,, the overcurrent protection is always "Ahead" of it's point of supply,,, unless your talking about tapping the load side of a transformer or the like, I just dont see the difference.


JAP>

 

[Smart $]

I think not. A feeder directly connected to a feeder breaker does not meet the definition of "tap conductor." This requires some close reading and a high degree of just believing anything I say. :happyyes: But here it is anyway: A tap conductor is defined as one that has overcurrent protection ahead of its point of supply in excess of the conductor's ampacity. In this installation, the conductor has overcurrent protection "AT" its point of supply, not "AHEAD OF" its point of supply. So it's not a tap. QED.

Adjunct to Don's reply, you must consider that a breaker or fuse block terminal does not provide overcurrent protection. The overcurrent protection is still AHEAD of the point of supply even though it may be part of the same device.

 

[iwire]

Unless this tap is outside the building 500' is a bit long

 

[Smart $]

Unless this tap is outside the building 500' is a bit long

And the assumption I made in bringing up the tap rules.

However, the common problem with outside tap of unlimited length is the location of the supply termination being indoor. Only the load end is permitted to be indoor.

Where the conductors are located outside of a building or structure, except at the point of load termination...

 

[iwire]

And the assumption I made in bringing up the tap rules.

I have no idea why anyone above made that assumption particularly with this fact

Only the load end is permitted to be indoor.

It seemed to me that in the rush to prove Charlie B wrong the OP had been forgotten.

 

[Smart $]

...It seemed to me that in the rush to prove Charlie B wrong the OP had been forgotten.

Seems to me that Don covered that...

240.4(B) permits the #1s to be protected by the 150 amp breaker in this application.