Brain dead tonight

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ceb58

Senior Member
Location
Raeford, NC
A friend call me today asking a question That I am brain dead on due to a cold. He has set a 400amp meter combo with 2-200amp main breakers. He has ran 2-30ft runs of 4/0 alum. ser to 2-200 main breaker panels. He after the fact remembered the 08 ruling on se cable in the 60 deg. collum but thought that since NC is revisiting the issue he could get away with it. I said that until they decided one way or the other he was wrong on wire size. He then ask, and I cannot answer because I just dont feel like looking ever thing up, could he change the breakers in the combo to 150amp and leave the 200's in the sub panels?
 

chevyx92

Senior Member
Location
VA BCH, VA
A friend call me today asking a question That I am brain dead on due to a cold. He has set a 400amp meter combo with 2-200amp main breakers. He has ran 2-30ft runs of 4/0 alum. ser to 2-200 main breaker panels. He after the fact remembered the 08 ruling on se cable in the 60 deg. collum but thought that since NC is revisiting the issue he could get away with it. I said that until they decided one way or the other he was wrong on wire size. He then ask, and I cannot answer because I just dont feel like looking ever thing up, could he change the breakers in the combo to 150amp and leave the 200's in the sub panels?

Of course!
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
doubt it's a problem, but we would have to go back to the original load calculations on the house and on each panel. Someone decided on a 400 amp service for some reason. If they did so based on actual Art 220 calcualtions, then there would be a problem.
Also, I see a lot of 400 amp services, split into two feeders where the electrician does not take the needed care to properly distribute the load between the panels.
 

360Youth

Senior Member
Location
Newport, NC
I would agree that it is going to come down to calculated load. Most 400 amp loads are more dependent on total # of circuits as opposed to actual load, so I would expect that he is going to come in under the 150 amps per panel. I have had the same thoughts in ways of getting around the new issues. If it is only 30' how hard would it be to run conduit and THHN? I have an upcoming house and that is the route I am most likely going.
 

ceb58

Senior Member
Location
Raeford, NC
doubt it's a problem, but we would have to go back to the original load calculations on the house and on each panel. Someone decided on a 400 amp service for some reason. If they did so based on actual Art 220 calcualtions, then there would be a problem.
Also, I see a lot of 400 amp services, split into two feeders where the electrician does not take the needed care to properly distribute the load between the panels.

More clairifacation. This job he is doing is on a church. It originally had a 200amp service and needed the upgrade because they were changing out a 5 ton gas pack to a heat pump with 15kw. heat strips. They also wanted stuff cleaned up due to years of jack leg wireing. I think he planes to feed the hvac system, crawl space recpt. and lighting from one panel and pick up the lighting and general use recpt. from the other.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
if it is a dwelling than wouldn't it comply as is. per table 310.15(b)(6)

Table 310.15(B)(6) does not apply to the sub panels since they don't carry the entire load of the house.

Ceb-- this happened to a friend of mine. He changed the breakers to 150 amp since the load worked in his case. No reason you cannot use 150 amp breakers in the main panel as long as the load permits it.
 

thetacon

Member
in this situation it does not apply. But if it were a home, it is not clear to my why table 310.15(b)(6) can not be used. in 310.(15)(b)(6) it states feeder(s) and Panelboard(s) are allowed to use the table. then in the interpertation below it it says that it is allowed even if other loads are fed from the same service. ( not enforceable but shows intent) what am i missing?
thanks for your help
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
in this situation it does not apply. But if it were a home, it is not clear to my why table 310.15(b)(6) can not be used. in 310.(15)(b)(6) it states feeder(s) and Panelboard(s) are allowed to use the table. then in the interpertation below it it says that it is allowed even if other loads are fed from the same service. ( not enforceable but shows intent) what am i missing?
thanks for your help


If the feeder carried the entire load of the service then you could use (B)(6) for dwellings. In the case of 2- 200 amp panels then each panel is not carrying the entire load of the dwelling. Thus the sub panels are not allowed to use Table (B)(6)
 

360Youth

Senior Member
Location
Newport, NC
Has anybody had cause to get prices on such cables, yet? I talked to supply house sometime back and they had no idea of new code issues and looked at me a little cock-eyed. I went online and found that they at least make the cable if need be, but I have not confirmed any prices.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Table 310.15 is out the door, then, regardless. Unless you convice AHJ it is the house of God. :smile:
LOL

I just went looking, and found the proposal that ended SE cable's use of the 75? column:

7-88 Log #2639 NEC-P07 Final Action: Accept
(338.10(B)(4)(a))
____________________________________________________________
Submitter: James M. Daly, General Cable
Recommendation: Delete the phrase ?excluding 334.80? and change the
comma after ?Article 334? to a period.
Substantiation: When Type SE conductors are used for interior wiring, as a
replacement for Type NM cable, the ampacity of the conductors should be the
same as permitted for NM cable since the insulations used are the same both
NM and SE conductors.
Panel Meeting Action: Accept
Panel Statement: This action will modify the action taken on Proposal 7-84.
Number Eligible to Vote: 14
Ballot Results: Affirmative: 14

That's a pretty short substantiation for such a sweeping change, but it makes sense, I guess.

I think in the OP, he's stuck with 150A breakers, if the calculated load permits.
 
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