Garage Feeder:

[augie47]

This has been dis-cussed previously but from reviewing threads, I'm not sure we had an agreement.
Two questions concerning a detached garage:
#1: 225.39 states when we have more than two circuits, the disconnecting means must have a 60 amp rating. Does that automatically infer the feeder must also have a 60 amp rating ?
#2: Since 225.33 allows 6 circuits for the main. Would a panel with a minimum of a 60 amp rating and 4 branch breakers (no main) suffice for the "60 amp rating" in 225.39 since there is no single "switch" ?

 

[infinity]

IMO question #1, feeder no. #2, Still on the fence. :roll:

 

[Dennis Alwon]

IMO, the wording for #1 does not support the idea that the feeder should be 60 amps but I think that is a ridiculous rule.

I have no issue with #2.

 

[don_resqcapt19]

The issue with Q2 would be the listing. The code rule requires the disconnect to be suitable for use as service equipment. Most of the listings for panels of that size say that they are suitable for use as service equipment only when they are equipped with a main breaker.

 

[jamesoftn]

If "rating" is the key word, would this mean that a one family dwelling could be a 60 amp load / service as long as the equipment was rated at 100 amps or more? 230.79 and 225.39 have the exact same wording "Rating"

I was under the assumption that a one family dwelling required a minimumn of 100 amps of service not one rated at 100.

 

[augie47]

That's a good point.
My thought is that the 60 amp disconnect requirement in Art 225 "intends" for the circuit to be 60 amps, but that's not what it says.
The only difference with that and the 230.79 requirement that I can see is that in the Art 225 situation your supply conductors have OCP at some point upstream that protect them where as your service conductors do not.
That said, applying the same logic, one could size the service conductors based on the required 230.42, install a 100 amp disconnect & "down-size" it to meet the load requirement and the conductor ampacity.
It might be better to let sleeping dogs lie and just say minimum service to a dwelling is 100 amp and minimum feeder to the 3+ circuit detached structure is 60 amps. I don't however see that wording.
Looks like a good 2014 proposal for Jamesoftn.

 

[mcclary's electrical]

That's a good point.
My thought is that the 60 amp disconnect requirement in Art 225 "intends" for the circuit to be 60 amps, but that's not what it says.
The only difference with that and the 230.79 requirement that I can see is that in the Art 225 situation your supply conductors have OCP at some point upstream that protect them where as your service conductors do not.
That said, applying the same logic, one could size the service conductors based on the required 230.42, install a 100 amp disconnect & "down-size" it to meet the load requirement and the conductor ampacity.
It might be better to let sleeping dogs lie and just say minimum service to a dwelling is 100 amp and minimum feeder to the 3+ circuit detached structure is 60 amps. I don't however see that wording.
Looks like a good 2014 proposal for Jamesoftn.

I don't agree that it's a good proposal. Plenty of times there are more than 3 circuits in a shed or small shop. One for lights, one or two for receptacles, The 60 amps IMO is way overkill. What I usually do to meet the requirement when the customer doesn't need much power is run a 10/3, feed with a 30 from the house. Then, when I get to the shed, I set a MLO panel, set a 60 amp main w/ holddown and call it a day. The 60 amp feed would be overkill in this situation.

 

[suemarkp]

If "rating" is the key word, would this mean that a one family dwelling could be a 60 amp load / service as long as the equipment was rated at 100 amps or more? 230.79 and 225.39 have the exact same wording "Rating"

I was under the assumption that a one family dwelling required a minimumn of 100 amps of service not one rated at 100.

The difference between the feeder and service situation is 230.90. In a service, the disconnect can't be larger than the ampacity of the wire (except for round up rules). The feeder has no such restriction, since it has proper protection at its source (unless its a feeder tap, and then you'd better have 60A wire if you have a 60A disconnect).

 

[iwire]

I have read a CMP statement that basically said 'It says what it says' the requirement is about the disconnect size only and has nothing to do with the feeder size.

 

[M. D.]

I have read a CMP statement that basically said 'It says what it says' the requirement is about the disconnect size only and has nothing to do with the feeder size.

Is this the one, from the ROP 2007

4-26 Log #2194 NEC-P04 Final Action: Reject
(225.39, FPN )
______________________________________________________________
Submitter: David Williams, Lansing, MI
Recommendation: Revise as follows:

The rating feeder or branch-circuit disconnecting means shall have a rating of
not less than the load to be supplied, determined in accordance with Parts I and
II of Article 220 for branch circuits. Parts III or IV of Article 220 for feeders,
or Part V of Article 220 for farm loads. In no case shall the rating be lower
than specified in 225.39(A), (B), (C), or (D).

FPN: The rating of the overcurrent device protecting the feeder does not need
to be rated to the minimum rating in this section.

Substantiation:
The code section specifies the minimum rating of the
disconnect and is not clear that the feeder or branch circuit needs to be rated
for this minimum rating. As an inspector, I am not positive if this section only
applies to the rating of the disconnect or does this mean that the minimum size
of a feeder to a building should be 60 amperes.
Just trying to clear up a concern.

Panel Meeting Action: Reject

Panel Statement: An additional FPN is not necessary. The title of 225.39
defines the requirement as solely being the rating of the disconnect.
Number Eligible to Vote: 10
Ballot Results: Affirmative: 10

 

[M. D.]

The issue with Q2 would be the listing. The code rule requires the disconnect to be suitable for use as service equipment. Most of the listings for panels of that size say that they are suitable for use as service equipment only when they are equipped with a main breaker.

What size is the panel ?

A panelboard with the neutral insulated from the enclosure may be marked ?Suitable for use as
service equipment when not more than six main disconnecting means are provided? when the
following conditions are met:

A. There must be at least one combination of switching units that can be mounted to
occupy all available space for switching units; and, whether by using handle ties or
similar devices, not more than six main disconnects will result (including factory-installed
disconnects)..............

there is more and it can be found here..
http://www.ulenvironment.com/global/...2006_Final.pdf

 

[M. D.]

I guess the above link does not work ,... perhaps this one will . It should bring you to the UL marking guide for panelboards .

http://www.ulenvironment.com/global...newsletters/PanelboardsMG_March2006_Final.pdf

 

[don_resqcapt19]

I can't find a label now, but I have seen labels panels that state, "suitable for use as service equipment only when a main breaker is installed".

 

[M. D.]

I can't find a label now, but I have seen labels panels that state, "suitable for use as service equipment only when a main breaker is installed".

Me too, now I wonder if there was no combination of switching devices with or without the use of handel ties... that would meet the listing requirement for the above .... My guess is that that would be it .

225.36 Suitable for Service Equipment.
The disconnecting means specified in 225.31 shall be suitable for use
as service equipment.

If in article 225.36 they had used the word.." Marked" after "be" and before "suitable for use as service equipment".

it would be a bit easier to understand :-? ,... perhaps? Because if it were marked as suitable for use as service equipment .....then we would have to use one of these ??

22. Some panelboards may have the required number of handles and service overcurrent devices,
when the maximum number of the smallest units are installed and used without handles ties or
similar devices. These panelboards may have the shorter marking ?Suitable for use as service
equipment? or ?Suitable only for use as service equipment.? ..........

 

[tortuga]

4-26 Log #2194 NEC-P04 Final Action: Reject
(225.39, FPN )
__________________________________________________ ____________
Submitter: David Williams, Lansing, MI
Recommendation: Revise as follows:

The rating feeder or branch-circuit disconnecting means shall have a rating of
not less than the load to be supplied, determined in accordance with Parts I and
II of Article 220 for branch circuits. Parts III or IV of Article 220 for feeders,
or Part V of Article 220 for farm loads. In no case shall the rating be lower
than specified in 225.39(A), (B), (C), or (D).

FPN: The rating of the overcurrent device protecting the feeder does not need
to be rated to the minimum rating in this section.

Substantiation:
The code section specifies the minimum rating of the
disconnect and is not clear that the feeder or branch circuit needs to be rated
for this minimum rating. As an inspector, I am not positive if this section only
applies to the rating of the disconnect or does this mean that the minimum size
of a feeder to a building should be 60 amperes.
Just trying to clear up a concern.

Panel Meeting Action: Reject

Panel Statement: An additional FPN is not necessary. The title of 225.39
defines the requirement as solely being the rating of the disconnect.
Number Eligible to Vote: 10
Ballot Results: Affirmative: 10

The title of 225.39 defines the requirement as solely being the rating of "the feeder or branch-circuit disconnect" There is not much clarity of singular or plural in "disconnecting means". Is the disconnect required by article 225 the only "disconnecting means" in the chain considered to be the feeder or branch-circuit disconnect?
Or is it any thing in the feeder circuit that meets the liberal article 100 definition of "disconnecting means"?
Examples:
1) What if there was a meter base or another knife switch in the feeder would they have to be rated 60A?

2) In the situation where there is a 50A feeder breaker in a main panel, then a feeder to a out building, then a 60A main breaker in the out building, does the 50A feeder breaker in the main panel not meet the definition of a "disconnecting means" in art 100?

3) If there were a 60A rated fused knife switch at each end with 50A fuses installed that would be OK?

 

[suemarkp]

I would say the disconnecting means is the one that meets all the requirements of article 225.32 - 225.39. One specific requirement is that it be nearest the point of entry of the conductors to that detached building. So I think you're only going to have one disconnect, and it will be the one nearest the feeder entry to the building as long as all the other requirements are met.