Subpanel: getting from here to there

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Old 06-24-19, 03:53 PM
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Subpanel: getting from here to there

I want to upgrade the power to a detached garage. The challenge is getting from the breaker box to the place where the (nice, big) buried conduit leaves the house. The wiring now runs through the walls, and that's not an option.

It's a southwestern style house with flat roofs. The only thing I see is to run up the wall from the box, punch through parapet, wander a bit (some intermediate height changes and walls),, then come out through the parapet and down the wall at the other end.

So, can I use SER cable? Because (a) it has to bend sharply to get through the parapet, and (b) if it has to transition to individual wires before the conduit, how can I do that? This is for 100A service in sunny Arizona.
 
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Old 06-24-19, 04:37 PM
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1-1-1-3 Al SER can be used for 100A and you will need a large junction box at end of conduit to splice to the individual wires that will go through the conduit.
 
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Old 06-25-19, 04:38 AM
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Hi, how do plan on securing the SER? a pic of the roof area might be helpful.
Geo
 
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Old 06-25-19, 12:48 PM
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I do not believe SER is rated to be in the sun.
The farther away the load the bigger the wire has to be.
Then there is the derate factors which sunny days in Arizona are going to be needed. When I did wiring in the Phoenix area I would purchase 90C wire and use the 60C table. If you chose #1 Al the 90C load is 115 amps and the 60C load is 85 amps. You need to know the distance and load to choose a conductor.
Lastly there is the making the roof waterproof again. I spent 30 years in Phoenix doing electrical work. I did 3 flat roofs, the best way I knew. They all leaked. I never did another flat roof again.
Have you considered underground around the perimeter of you structure?
 
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Old 06-25-19, 03:31 PM
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SER is sunlight resistant.
https://www.mysouthwire.com/medias/s...4083371038.pdf
 
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Old 06-27-19, 10:24 PM
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I've never dealt with aluminum wire and had been figuring on copper, probably around 3-3-3-5. Also, I'd been figuring this out for individual wires in conduit, but don't want to miss out if SER is better. (Better meaning easier, cheaper, or both.)

There would be no holes in the roof. The cable or conduit would go up the wall, punch through, then run along the inside of the parapet above the roof. High enough above it there's no watertightness issue. Burying...no, that won't work. There's too much stuff buried there already.
 
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Old 06-28-19, 05:11 AM
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SER is easier to install, and a little cheaper, but conductors in conduit is more durable. Either is OK by code so it's your choice. I would probably use EMT conduit along the building walls and parapet with THHN wires pulled in. This method could also eliminate the splice box if you gauge the pull correctly.
 
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Old 06-28-19, 05:24 AM
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Hi, THWN for wet locations, I believe.
Geo
 
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Old 06-28-19, 05:38 AM
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True, but they are essentially the same thing nowdays as all commonly available THHN also carries a THWN-2 rating. Southwire, Cerrowire, General Cable, for example all list THHN and THWN-2 as the same product in their catalogs.
 
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