Electrical code ? Wire type indoor vs buried

[C4Ranch]

Trying to figure out the wire type needed to run to a sub panel in barn.

Want to run 150' in attic (no conduit) of main house, come out by garage and then 50' under ground (in conduit).

Planning on 2/3 with #4 ground... 100amp

From what I can tell, cannot run URD in attic but could be an option from garage to barn if I put a j-box at garage.

What kind of wire can I run in the attic that requires no conduit? Can I run 2/3 SEU with a separate #4 copper ground wire the whole way and in the attic without conduit?

Thx!

 

[JPRambo]

SER service entrance cable. I'm guessing aluminum ( if copper that is awful large for 100 amp).



Here we can under size 1 size for residential. So 4/4/6/8 would work if you can find it.

 

[C4Ranch]

SER service entrance cable. I'm guessing aluminum ( if copper that is awful large for 100 amp).

Thx! Was thinking aluminum. So is SER acceptable to run in attic without conduit? When I go to running in ground from garage to barn in conduit, can I use same SER or do I need to go to SEU or URD?

 

[quicksandfarmer]

Multi-conductor cable is not meant to be run in conduit. Put a junction box where the conduit enters the house and switch to individual conductors. Or run conduit the whole length. At my Home Depot 150 feet of 1-1/4" PVC is about $65. You would more than make that up by using THHN instead of SEU through the attic.

 

[s219]

If you decided to use conduit in the attic, you could get XHHW-2 wire and use that the whole way. It can be used indoors, outdoors, or underground as long as it's in conduit. They make it in both copper and aluminum.

Otherwise, you could use SER in the attic with no conduit (in fact it should not be used in conduit) and then transition over to URD for the outdoor run. The SER is available with 3 conductors and smaller ground inside the bundle. I don't think you can run a separate ground wire in the attic, so I'd say get SER with the ground inside the bundle.

Technically, you can use 2-2-2-4 aluminum wire for a 100A service feeder to a panel (as a branch, it's limited to 90A). However, over 200', I'd say run the voltage drop calculation to see if you should upsize.

 

[s219]

Thx! Was thinking aluminum. So is SER acceptable to run in attic without conduit? When I go to running in ground from garage to barn in conduit, can I use same SER or do I need to go to SEU or URD?

You cannot run SER or SEU inside conduit except for short runs, say to get into a circuit panel, from meter to panel, etc.

Generally NEC looks at bundled jacketed wire as already being in a "raceway" (the jacket counts) and you cannot put a raceway (jacket) inside another raceway (conduit).

 

[grsthegreat]

If you decided to use conduit in the attic, you could get XHHW-2 wire and use that the whole way. It can be used indoors, outdoors, or underground as long as it's in conduit. They make it in both copper and aluminum.

Otherwise, you could use SER in the attic with no conduit (in fact it should not be used in conduit) and then transition over to URD for the outdoor run. The SER is available with 3 conductors and smaller ground inside the bundle. I don't think you can run a separate ground wire in the attic, so I'd say get SER with the ground inside the bundle.

Technically, you can use 2-2-2-4 aluminum wire for a 100A service feeder to a panel (as a branch, it's limited to 90A). However, over 200', I'd say run the voltage drop calculation to see if you should upsize.

What he said is 100% correct.

 

[Industrial Toys]

That's something I learned here. I used to put jacketed cable in conduit (for ug stuff) figuring I was doing a one better type of thing! Fortunately, usually the conduits were rather large.

Personally, I would not use aluminium for anything, except overhead or main underground service.

 

[buickanddeere]

What are the plans for over current protection and grounding ?

 

[LD1]

That's something I learned here. I used to put jacketed cable in conduit (for ug stuff) figuring I was doing a one better type of thing! Fortunately, usually the conduits were rather large.

Personally, I would not use aluminium for anything, except overhead or main underground service.

From a common sense standpoint, underground is a different thing. Not a NEC code guru, but the whole Idea of not having "cable" like SER inside conduit is to keep the wire from overheating. Allowable ampacities are all based on how much heat can the insulation sustain before breaking down. Thats why there are charts for the allowable number of current carrying conductors allowed, what gauge, and what size conduit. More wires and smaller conduit = more heat.

In reality, burrying SER in conduit in the GROUND, the wire will stay cool. Attic would worry me.