Residential Feeder thru Underground Conduit

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Jimland58

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Building a house that has a main outdoor panel that will feed 2 subpanels. One of the subpanels will be a 200 amp main lug type panel located inside the house and my plan was to run about 80' of SER 1/0-3 aluminum cable thru the attic fed by a 110 amp feeder breaker in the main panel. The second subpanel will be a 100 amp main breaker panel located in a metal building shop behind the house. The feeder cable for this shop subpanel will run about 100 ' thru the attic and then about 50' thru underground conduit to the shop subpanel. I know I could use #1 size aluminum cable but because of the length of this feeder (150') I was thinking to go up one size to 1/0 to address voltage drop.

My understanding is I cannot use SER cable for this shop feeder because of the section of underground conduit. So what type of 1/0 aluminum 3 conductor jacketed cable can I use to run thru the attic and the underground conduit for this feeder?
 
I don't know of any jacketed cable, other than outside rated MC cable, that could be run in conduit outdoors.
I would probably run the SER over to where it exits the house/attic, then place a junction box and transition to THWN (or other direct burial cable such as mobile home feeder) for the conduit run.
 
The inners of mc are either thwn-2 or xhhw-2 so I only see the bare aluminum ground as being the issue underground. You could just pull a proper egc in with the cable. Clearly you would still need a box to make the egc transition.
 
#1 Al is only rated for 100 amps so it would be too small with your 110 amp OCPD. For 110 amps you would need a minimum of #1/0 anyway.
 
infinity said:
#1 Al is only rated for 100 amps so it would be too small with your 110 amp OCPD. For 110 amps you would need a minimum of #1/0 anyway.
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Sorry, wasn't clear in my post. The first sub panel will be fed by a 110 amp OCPD and the SER 1/0-3 aluminum cable runs 80' thru only the attic. The second sub panel is to a shop and will be fed by a 100 amp OCPD and the cable runs 100' thru the attic and then thru a section of 50' of underground conduit. So for this 100 amp shop feeder, I could use a #1 aluminum but I was going to go up one size to 1/0 aluminum to address voltage drop.

So ....... there is no one who sells a 1/0-3 aluminum cable that can be run thru both an attic and underground conduit????
 
Jacketed MC feeder cable is your only option if you are dead set on a cable. If you are running it through an attic, it sounds like you are going to have to LB out of the wall at some point.

Run SER through the attic to a jbox on the wall that you are LBing into, nipple the lb into the jbox and transition to single conductor XHHW Al.
 
ppsh said:
Jacketed MC feeder cable is your only option if you are dead set on a cable. If you are running it through an attic, it sounds like you are going to have to LB out of the wall at some point.

Run SER through the attic to a jbox on the wall that you are LBing into, nipple the lb into the jbox and transition to single conductor XHHW Al.
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If we say this one more time, that would be three times (see post #2), and we know the 3rd time is a charm!
 
The 2017 code would permit TC-ER cable, but only the type that also contains control conductors....however no requirement to use the control conductors. This is the cable that Generac got into the code for the power and control conductors between the generator and the transfer switch, but is not restricted to that application.
 
More I look at it.. no a good alternative.. in re-reading 336.10 the cable would have to be identified "JP" fo use un residential (other than in a raceway) and I doubt one can find "JP" + control in that large a cable.
 
Little Bill said:
I don't know of any jacketed cable, other than outside rated MC cable, that could be run in conduit outdoors.
I would probably run the SER over to where it exits the house/attic, then place a junction box and transition to THWN (or other direct burial cable such as mobile home feeder) for the conduit run.
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What about USE Cable?
 
Adamjamma said:
I thought USE is allowed inside as long as it is inside Conduit
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No, unless it is also marked with other designations that are allowed inside. Still must be inside some other chapter 3 wiring method or direct buried.

338.12(B) uses not permitted first item mentioned is "for interior wiring". If it has additional conductor type markings, that is what makes it acceptable per those markings. If it is only marked "USE" then it is not permitted inside.
 
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