wiring help for sub panel

[east_tn_emc]

I am installing a 100amp subpanel in my detached garage. I plan to bury conduit between house and garage (roughly 50 feet) and run #2 THHN/THWN from the subpanel thru the conduit and into a disconnect switch mounted on the outside of the house.
I will then have another 20 feet to run cable INSIDE the house into the main electric panel.
My question is this:
Since I cannot use (my understanding anyway) the 4 runs of THHN inside the house without putting them in conduit, what type of wiring should I run inside the house and not have to run conduit inside the house?

Thanks.

 

[mrb]

few things:
you dont need 4x #2, you can use a #6 for the ground.

why not run conduit in the house?

If you dont want to run conduit in the house you can run cable and a junction box to splice it to the THHN, but by the time you buy the larger cable, the jbox, and the polaris blocks to splice it, you will wish you just ran conduit.

 

[porschedude996TT]

few things:
you dont need 4x #2, you can use a #6 for the ground.

why not run conduit in the house?

If you dont want to run conduit in the house you can run cable and a junction box to splice it to the THHN, but by the time you buy the larger cable, the jbox, and the polaris blocks to splice it, you will wish you just ran conduit.

What mrb said. No reason to change materials mis stream. I just ran my 100 amp subpanel service 70' in 1-1/4 PVC Conduit external of my house, then it dives under the concrete and into the sub-panel. I used an "LB" about in the middle and pulled each end outward to the panels. #2 times three and a #8 bare ground wire.

As I was told, you can use NEC Chapter 250.122 because its an equipment ground and not a service ground. So its a #8 copper ground.

 

[Aceman]

I am installing a 100amp subpanel in my detached garage. I plan to bury conduit between house and garage (roughly 50 feet) and run #2 THHN/THWN from the subpanel thru the conduit and into a disconnect switch mounted on the outside of the house.
I will then have another 20 feet to run cable INSIDE the house into the main electric panel.
Thanks.

What's the disconnect for? It's not required, you can run straight from you garage subpanel in conduit straight to your main panel in your home if you like.

To save you some headache, I'll tell you right now, #2 AL SER is the most common along with 4/0 SER at my supply house, any other size and I have to order it. No big deal really, just something to be aware of. But, if you're shopping at HD and Lowes it might be an issue, I don't know how available it is through them??

With that in mind, #2 AL SER's ampacity is now taken from the 60 degree chart in Table 310.16, limiting it to 75 amps. Which means you can breaker it at 80 amps as long as the calculated load doesn't exceed 75. Otherwise, you'll need a 70 amp breaker. But that's not quite the 100 amps you're looking for...

To get the full 100 amps, you'll need to run 1/0 AL SER cable. But this isn't as common and most likely will need to be ordered. And like MRB said, it takes $20 dollar insulated taps times four of 'em to splice it plus a junction box large enough to do it in.

 

[mrb]

yeah #8cu ground for 100 amps....i was thinking 200 amps

 

[Gary S]

I did it the simple way. I just ran conduit in the house and garage so the wires didn't need to be spliced in a box along the way. It is much neater this way.