EC mag. / Code Q&A

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stickboy1375 said:
Thats how i've always read it also, hopefully too many people reading the article dont get confused...
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The way it's written, the author implied that #12 is too small because of the 30 amp disconnect requirement. At least that's how I'm reading it. If that's the case, then I disagree with the author. The #12 is fine so long as there is a 30 amp rated disconnect at the remote structure.
 
peter d said:
The way it's written, the author implied that #12 is too small because of the 30 amp disconnect requirement. At least that's how I'm reading it. If that's the case, then I disagree with the author. The #12 is fine so long as there is a 30 amp rated disconnect at the remote structure.
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Peter, I read it the same way.
 
stickboy1375 said:
Thats how i've always read it also, hopefully too many people reading the article dont get confused...
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I agree that is how the code reads but I think it is ridiculous to require a 30 amp disco without requiring a 30 amp feeder. I always pull a 30 amp feeder minimum in that scenario.
 
stickboy1375 said:
I read this and find this untrue... anyone else?




? NEC 225.39(B) requires for a two-circuit installation that the disconnecting means be rated not less than 30 amperes. Now comes our first problem. You are using 12 AWG conductors in your feeder, and the two-circuit installation requires a 30-ampere disconnect. (Strike one!)



http://www.ecmag.com/index.cfm?fa=article&articleID=8918
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I agree with you, 12/3 = 1 circuit
 
stickboy1375 said:
Thats not the controversy, the author is saying you must run a 30 amp wire to the outbuilding because the DISCONNECT is required to be 30 amps.
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And the Author is wrong,.. and not only that you can add the ratings of separate disconnects together to arrive at 30 amps,..

http://www.iaei.org/subscriber/magazine/06_d/johnston.html

......Section 225.39 has been revised by adding a new second sentence to clarify that when more that one switch or circuit breaker is used as the disconnecting means for a feeder supplying a separate building or structure, the combined ratings of the switches or circuit breakers used as the service disconnecting means can be added together to achieve the minimum rating required for the disconnecting means...
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Stickboy--what do you think of the other Q & A on NM-- specifically the last sentence in the answer. I don't see where NM cannot be run in conduit.

If NM cable is run under the shelter of a patio roof or in an overhang where it?s not subject to mechanical damage and not out in the weather, then it should be fine, right? Also, if the NM cable is run in a metal conduit outdoors and isn?t subject to the weather, what would be wrong with that?
Hey man, are you asking or telling? NEC 334.12(B)(4) is very clear. Type NM cable shall not be used in wet or damp locations. Under a patio roof or in an overhang is a damp location. Before you consider running NM cable in a metal conduit, check the raceway articles under 342.22, 344.22 and 358.22. They all say, ?Cables shall be permitted to be installed where such use is not prohibited by the cable article.? Type NM cable cannot be run in any raceway, other than using the raceway as a sleeve for protection in accordance with 334.15(B) and 300.154(C).
 
Not trying to bash Charlie Trout but, he is in fact answering these questions incorrectly.

Roger
 
This proposal for the 2008 clears it up if there was any doubt. :smile:

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
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stickboy1375 said:
Thats not the controversy, the author is saying you must run a 30 amp wire to the outbuilding because the DISCONNECT is required to be 30 amps.
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Well here's another conundrum. Charlie T starts off...
NEC 225.30 requires that a separate structure be supplied by only one feeder or a single branch circuit. A multiwire branch circuit is considered a single circuit. (So far, so good.)

...

NEC 225.39(B) requires for a two-circuit installation that the disconnecting means be rated not less than 30 amperes. Now comes our first problem. You are using 12 AWG conductors in your feeder, and the two-circuit installation requires a 30-ampere disconnect. (Strike one!)
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The conundrum is that he calls attention to 225.39(B) Two-circuit Installations. These installations must first qualify under 225.30(A) through (E)... and the installation under scrutiny does not.

Regardless, the discussed installation falls under 225.39(A) One-circuit Installation as he so noted earlier, and is only required to have a minimum 15 ampere rated disconnecting means.
 
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