#2 URD Direct burial

[Buck Parrish]

I don't use URD very often . I am estimating a horse barn. The guy wants a 100 amp panel. He even went as far to upgrade his home service to 400 in preperation to go to 100 amps for the barn.
So this would be a feeder from his home panel. That dis - allows 310. 15b
I told him the ampacity of #2 has been reduced to 80 amps.
Am I right ?
Do you have to use the 60 degree column with direct cable. I know lots of states still allow it on a 90 due to the fact thier on the 05 code.

Which is right in NC under NEC 08? Is it 80, 90 or a 100 amps. Thanks in advance.

 

[LarryFine]

The problem is URD isn't in the NEC, so you need a recognized or dual-rated insulation type.

 

[Dennis Alwon]

Buck- Hunt sells #2 aluminum direct burial that is dual rated and cost $1.18/ft. It has 3- #2 and a ground. It is rated 90amps at 75C. This is not se cable but USE cable so it doesn't fall under the 60C. The wire at Hunt is RHW & RHW-2.

 

[jwjrw]

The last one I did I thought they were going to make me add bonding grids to the existing barn. Read Art 547 before you bid it.

 

[Cow]

Make sure you and your inspector understand what's required for an equipotential bonding grid if there will be any concrete slabs where livestock stand.

We're in the process of wiring a large dairy barn. All slabs have mesh/rebar in them. We also have to hit any isolated metal fencing/metal troughs/gate posts, etc and bond them to the mesh.

The Burndy crimps we're using to tail #8 copper from the concrete mesh are $3 apiece. We've used about 400 so far....

And a ton of rebar clamps too....

If your barn is all dirt floors, you got it easy!

 

[kwired]

Read 547.10(A) carefully, just because there is a concrete floor does not automatically mean an equipotential grid is required.

 

[kwired]

I don't use URD very often . I am estimating a horse barn. The guy wants a 100 amp panel. He even went as far to upgrade his home service to 400 in preperation to go to 100 amps for the barn.
So this would be a feeder from his home panel. That dis - allows 310. 15b
I told him the ampacity of #2 has been reduced to 80 amps.
Am I right ?
Do you have to use the 60 degree column with direct cable. I know lots of states still allow it on a 90 due to the fact thier on the 05 code.

Which is right in NC under NEC 08? Is it 80, 90 or a 100 amps. Thanks in advance.

As for the size of conductor needed what is the load calculation? Same goes for whether upgrading the service to 400 amps is needed or not - just because you put a 100 amp panel in the barn does not mean you added 100 amps of load. If small barn with only a couple horses you may find that your load calculation is only 20 - 30 amps, or even less.