Feeder? Subfeeder?

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mtnelectrical

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Essex, New Jersey
Inspector fail me an inspection saying that my riser cable al 2-2-2-4 that I ran for a subpanel is only rated for 90 amps and that is not a feeder cable, it is a subfeeder. I put a 100 amps breaker on that wire. I have a 200 amps service back to back is meter pan and main breaker box witn 40 spaces, from this main braker box we run a subpanel for an adittion,this subpanel have 20 spaces and it is rated for 125 amps, we run the cable described above to feed this panel. Am I missing something? Thank you for your responses
 
raider1

raider1

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The NEC does not use the term "Sub-feeder".

What you have is a feeder that originates at a panel and terminates at a panel. This by definition is not a "main power feeder" so therefore Table 310.15(B)(6) can not be used so you must use Table 310.16 to size the feeder conductors.

If you are using a #2 aluminum SER cable then under the 2005 NEC this cable has an ampacity of 90 amps from the 75 degree column. 90 amps is a standard overcurrent device rating and therefore you must use a 90 amp breaker and can't use a 100 amp breaker.

Under the 2008 NEC SER cable must be sized based on the 60 degree column and therefore the #2 SER would have an ampacity of 75 amps and the next standard size breaker would be an 80 amp breaker.

Hope this helps

Chris
 
iwire

iwire

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Massachusetts
He did not explain it to well but the deal is this.

Unless the feeder carries the entire load for the home you can not use table 310.15(B)(6).

In your case the sub panel is not supplying the entire home so you must use Table 310.16 keeping in mind 334.80 limits SE used as NM to the 60 C column

2 AL @ 60 C is rated 75 amps, not 90. The max breaker you could use is an 80.
 
infinity

infinity

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Although the inspector missed on a few key things he did get one thing right and that is that you have a violation with the #2 SER on a 100 amp CB. As the others have said you'll need to use a maximum of 80 amp OCPD for protection of the subpanel feeder. If you truly need 100 amps you will have to run a new feeder using larger conductors.
 
infinity

infinity

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Pierre C Belarge said:
And...
NJ is on the 2008 NEC...looks like a larger cable or smaller OCPD.
Click to expand...

Although this is true it would depend on when the permit were issued. If the permit were issued under the 2005 NEC (still issued up to a few months ago) he could use a 90 amp CB.
 
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RICK NAPIER

Senior Member
Location
New Jersey
Permits applied for prior to 4/6/09 are 2005 NEC. Permits applied for between 4/6/09 and 10/6/09 are 2008 NEC unless specificcally requesting 2005 NEC. Permits applied for after 10/6/09 are 2008 NEC.
 
infinity

infinity

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One-eyed Jack said:
Does anyone here know the story behind this particular change? The omission of the words "excluding 334.80 "
Click to expand...

I think that it was to put SE cable in line with NM cable which already had the 60 degree limitation. In practical use IMO there was no real substantiation.
 
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mtnelectrical

Senior Member
Location
Essex, New Jersey
Thank you guys I just saw that, I missed it on my 10 hours course, I think it should be 30 instead of 10, we just flew over those changes. But thanks again, I love this forum , full of knowledgeable people.
 
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