Subpanel feed

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grayghost

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Tn.
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retired
I'm a retired electrian of (30 some years)retiring in 2008 and have not been keeping up with the codes.
johng

I am running a #2 se (non metalic) cable from a 200 amp house panel to a 100 amp subpanel in garage. There is a gable roof with no sides betwee the the two structures.
My question is, do i need to run conduit even though the wire would be protected from the weather?
johng
 
grayghost said:
I am running a #2 se (non metalic) cable from a 200 amp house panel to a 100 amp subpanel in garage. There is a gable roof with no sides betwee the the two structures.
My question is, do i need to run conduit even though the wire would be protected from the weather?
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No, if you mean the house and garage are connected and share a roof, but you have two other concerns:

1. If this feeder will be 120/240v, you need SER, not SE, because you need a separate ground and neutral.

2. #2 aluminum is not large enough for a 100a feeder, even though it is large enough for a 100a service.
 
Am I correct that the garage is detached and the cable will exit the gable end of the residence, be exposed for a short distance, and then enter the gable end of the garage? If so, I would put a sleeve of conduit between the buildings to protect and support the cable.

Also, if the distance is more than short, the rules for supporting that conduit must be followed.
 
#2 aluminum will need to be protected by a 90 amp breaker max.

It is only good for use with 100 amp breaker if it is supplying the entire load of a dwelling unit per special provisions in 310.15(B)(7), (B)(6) at one time, and now in 2020 things got rearranged and it is 310.12.
 
I was a little confused on the 90 amp for # 2 Al. Looked at the 83 percent and asked 2 inspectors and they agree it's good for 100 amp. Not to argue, still researching. Don't know about 2020 code.
 
Just an FYI, they make 100A rated SE cable (SER in your case). Just a few $$ more. Not sure how basic you want to get but make sure your neutral floats and the bare wire is bonded to the enclosure in the sub panel and you have to drive a ground rod and bond it to the breaker enclosure.
 
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