NJBESTOFTHEBEST
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- Location
- NEW JERSEY
CAN I USE #2 ALUMINUM FOR A 100AMP SUB=PANEL IN A RESIDENTIAL HOME??? CAN I USE CHART 310.15(B)(7)?? IS THIS CONSIDERED A FEEDER>??
====SUBPANEL RESIDENTIAL===
- Thread starter NJBESTOFTHEBEST
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jumper
Senior Member
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- 3 Hr 2 Min from Winged Horses
All Caps is considered as yelling, a bit rude, as a general rule.
However,welcome to the forum.
However,welcome to the forum.
Welcome to the forum :thumbsup:
BTW please do not use all caps. Considered yelling here, not to mention harder to read.
As for your question... it depends on several factors: the calculated load, overcurrent protection rating and where the ocpd is located, etc. No, you cannot use 310.15(B)(7) for a subpanel feeder unless it carries the entire calculated load for the dwelling (and of course a 120/240 system).
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NJBESTOFTHEBEST
Member
- Location
- NEW JERSEY
thanks for your reply. Where can I find that in the code? The sub-panel is actually 100% of the load. I added a new 200amp panel and out of that panel I added a 100amp sub-panel. This is taking the place of the old 100amp main panel. The 200amp panel currently does not have any other circuits. I ran #2SER to the 100 amp panel and the inspector said it has to be a 90amp.
Depending on the details of the installation, the Code cycle and the inspector, you could have been limited to a 75 amp breaker 
I think your only Code reference is going to be the wording in 310.15(B)(7). As installed, IMO, it meets the parameters to use the 100 amp breaker, but with the 200 amp panel as the service disconnect I can certainly see the inspector making the 90 amp call.
I think most inspections don't take "future" into account, but this one does beg toward that call.
I think your only Code reference is going to be the wording in 310.15(B)(7). As installed, IMO, it meets the parameters to use the 100 amp breaker, but with the 200 amp panel as the service disconnect I can certainly see the inspector making the 90 amp call.
I think most inspections don't take "future" into account, but this one does beg toward that call.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
It could be 75 amps as Augie stated once you add a single breaker in the 200 amp panel.
NJBESTOFTHEBEST
Member
- Location
- NEW JERSEY
310..15(B)(7) Confusion!!
310..15(B)(7) Confusion!!
According to 310.15(B)(7) it says: " For application of the section, the main power feeder shall be the feeder between the main disconnect and the panelboard that supplies, either by branch circuits or by feeders, or both, all loads that are part or associated with the dwelling.
To me this means if I add a sub panel it is considered a feeder and I should be able to run #2SE cable with a 100 amp main. One township said it is considered a feeder and ok for me to use this chart to size my wire and another township said its not a feeder!!
Whats everyones input?? I was told by one inspector that this has been a change over the years and that I am good to go with the #2 aluminum for a 100 amp sub-panel since it is a feeder.
310..15(B)(7) Confusion!!
According to 310.15(B)(7) it says: " For application of the section, the main power feeder shall be the feeder between the main disconnect and the panelboard that supplies, either by branch circuits or by feeders, or both, all loads that are part or associated with the dwelling.
To me this means if I add a sub panel it is considered a feeder and I should be able to run #2SE cable with a 100 amp main. One township said it is considered a feeder and ok for me to use this chart to size my wire and another township said its not a feeder!!
Whats everyones input?? I was told by one inspector that this has been a change over the years and that I am good to go with the #2 aluminum for a 100 amp sub-panel since it is a feeder.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
You can use the 100 amp OCPD and #2 Al if you comply with the first sentence in your post. IMO you've complied.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
What loads are not going to be associated with the dwelling unit requiring the 200A panel? If the panel is going to feed a barn or something you're compliant. If it's for an unfinished basement or something then the inspector is on thin ice but his reasoning is sound.
NJBESTOFTHEBEST
Member
- Location
- NEW JERSEY
The 200amp panel has no other circuits in it currently. It has a 100 amp 2pole feeding a sub-panel. The sub-panel use to be the main panel at one point when it was only a 100amp service. The sub-panel is currently carrying the total load of the house.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The inspector is looking into the future with his crystal ball. Like him we all know that someone will at some point add a circuit to the 200 amp panel.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Put a 90 amp breaker because as soon as someone adds another breaker in the 200 amp panel then the ser would be in violation. I agree as it is you are compliant
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If it's installed in thermal insulation would a 75 amp OCPD need to be used?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
IMO, no but yes it should be considered. The T. does not state we have to take derating into consideration.
BTW- Gus disagrees...
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
We don't know it will be a dwelling unit load unless the OP answers my question.
From what I'm gathering, there is a 100A breaker supplying your feeder... and it is not the main disconnect.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Smart,
Feeders between the main disconnect and the panelboard that supplies 100% of the house loads qualify. Any feeders in between that serve 100% of the house load are going to be between the main disconnect and the last panel that does.
Feeders between the main disconnect and the panelboard that supplies 100% of the house loads qualify. Any feeders in between that serve 100% of the house load are going to be between the main disconnect and the last panel that does.
Sorry, but I believe you are reading it wrong...
...the main power feeder shall be the feeder between the main disconnect and the panelboard that supplies, either by branch circuits or by feeders, or both, all loads that are part or associated with the dwelling.
What needs to be clarified here is whether the the 200A panel is MLO, with an SEC feeding it and the 100A breaker is the only main disconnect (i.e. the only service disconnecting means) for the dwelling. If there is a service disconnect ahead of the 100A breaker, then IMO it does not qualify... even though it is carrying 100% of the dwelling load.
The susceptibility of adding dwelling loads to the 200A panel doesn't matter as far as code is concerned. But why install a 200A panel? Surely not to just put one two-pole breaker in it...:slaphead:
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
So what is the point of the plural "feeders" in the sentence?
If the panel is a 200A Main Breaker Panelboard, then the feeder would be from the main disconnect to the 100% panelboard.
I agree, as far as code goes the code violation only takes place when the next breaker is installed in the panel, if the breaker serves the dwelling unit. Right now, I don't see a violation.
I agree that, as it stands with no other breakers installed in the 200 amp service panel, the #2 SER serves as the "main feeder" and would meet the NEC with a 100 amp breaker supplying provided that all the other stipulations of 310.15(B)(6) {'11 310.15(B)(7)} are met. (Dwelling unit, 120/240 volt single phase, etc.)
(As Dennis notes,I think there is a valid argument for a lesser size OCP based on the details of the installation and the interpretation of 338 and the 60? rating..but that's a whole different can of worms that I won't open)
(As Dennis notes,I think there is a valid argument for a lesser size OCP based on the details of the installation and the interpretation of 338 and the 60? rating..but that's a whole different can of worms that I won't open)
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