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Old 08-24-2016, 03:10 PM   #1
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Default 310.15(b)(7)(1)

Question. Can I use 310.15(B)(7)(1) to size the feeder to a detached garage/hobby shop? Thanks, biscuits.
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Old 08-24-2016, 03:18 PM   #2
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No, it has to be a dwelling unit to use that section.

So I will usually run #2 Al and install a 90A breaker for the inspection, then change it out to a 100A breaker afterwards. 90A breakers are too expensive to waste.
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Old 08-24-2016, 03:25 PM   #3
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Ugh that sucks. I think I'm just gonna do it. It's for family and I'm not getting paid enough to mess around with 90 amp breakers.
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Old 08-24-2016, 03:29 PM   #4
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Originally Posted by Biscuits View Post
Ugh that sucks. I think I'm just gonna do it. It's for family and I'm not getting paid enough to mess around with 90 amp breakers.
This is the stupid part of the code.

You can put 100A on #2 Al if it is powering everything in the dwelling unit. But if you take one load off of that panel, let's say something like an HVAC unit, you can no longer use that section and have to go down to a 90A breaker, even though you lowered the load. It's just silliness.

If this is for family and no inspection, use a 100A breaker without giving it a second thought.
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Old 08-24-2016, 03:50 PM   #5
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Originally Posted by Biscuits View Post
Ugh that sucks. I think I'm just gonna do it. It's for family and I'm not getting paid enough to mess around with 90 amp breakers.
Whats the big deal to use a 90 amp breaker instead of a 100 amp one. Put the 90 amp breaker at the house and you can keep the dp 100 that comes with the panel. That is compliant
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Old 08-24-2016, 03:52 PM   #6
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If it is overhead then you can use T. 310.15(B)(17)
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Old 08-24-2016, 04:29 PM   #7
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Originally Posted by Dennis Alwon View Post
Whats the big deal to use a 90 amp breaker instead of a 100 amp one. Put the 90 amp breaker at the house and you can keep the dp 100 that comes with the panel. That is compliant
We are talking about the 90A breaker in the house's panel that feeds the garage. He can keep the 100A breaker that comes with the garage panel.
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Old 08-24-2016, 04:58 PM   #8
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Originally Posted by HackWork View Post
We are talking about the 90A breaker in the house's panel that feeds the garage. He can keep the 100A breaker that comes with the garage panel.
That is what I said.... DP 90's cost the same as 100 amp breakers around here
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Old 08-24-2016, 05:06 PM   #9
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That is what I said....
Wow, that is what you said. I completely read that wrong. Are you sure that you didn't go back and edit your post?!?!
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Old 08-24-2016, 05:34 PM   #10
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Originally Posted by HackWork View Post
Wow, that is what you said. I completely read that wrong. Are you sure that you didn't go back and edit your post?!?!
And you give me crap about not reading your posts...
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Old 08-24-2016, 05:37 PM   #11
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And you give me crap about not reading your posts...
Yes, but notice that I admitted it!
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Old 08-24-2016, 06:35 PM   #12
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I could easily swap the feed breaker out for a 90 but I think they've already got a 100 amp main breaker loadcenter for the shop. Any reason why I couldn't leave the 100 amp main as long as the feeder breaker is reduced to 90?
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Old 08-24-2016, 06:38 PM   #13
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Quote:
Originally Posted by Biscuits View Post
I could easily swap the feed breaker out for a 90 but I think they've already got a 100 amp main breaker loadcenter for the shop. Any reason why I couldn't leave the 100 amp main as long as the feeder breaker is reduced to 90?
Yes, you could leave the 100A main. It's only serving as a disconnect.
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Old 08-24-2016, 06:39 PM   #14
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Quote:
Originally Posted by Biscuits View Post
I could easily swap the feed breaker out for a 90 but I think they've already got a 100 amp main breaker loadcenter for the shop. Any reason why I couldn't leave the 100 amp main as long as the feeder breaker is reduced to 90?
Its kinda like the service begins at the out building and the proper size wire has to be brought to it.
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Old 08-24-2016, 06:41 PM   #15
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Quote:
Originally Posted by HackWork View Post
This is the stupid part of the code.

You can put 100A on #2 Al if it is powering everything in the dwelling unit. But if you take one load off of that panel, let's say something like an HVAC unit, you can no longer use that section and have to go down to a 90A breaker, even though you lowered the load. It's just silliness.

If this is for family and no inspection, use a 100A breaker without giving it a second thought.
Lots of safety factor is calculated in feeder wire as opposed to an equipment branch circuit.
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Old 08-24-2016, 06:53 PM   #16
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Originally Posted by Suncoast Power View Post
Lots of safety factor is calculated in feeder wire as opposed to an equipment branch circuit.
What I mentioned is a feeder either way, no branch circuits were mentioned.
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Old 08-24-2016, 06:54 PM   #17
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Quote:
Originally Posted by HackWork View Post
Yes, you could leave the 100A main. It's only serving as a disconnect.


That's the spirit


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Old 08-24-2016, 07:31 PM   #18
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Quote:
Originally Posted by Dennis Alwon View Post
If it is overhead then you can use T. 310.15(B)(17)
Not really....see 110.14(C)(1).
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