Conduit sleeve size for URD

[HuckMeat]

I am installing 3 polemounts, and am running 2 sets of 4/0 AL URD (per my PV electrician, I'm doing the trench work, he's doing the electrical, but in Hawaii this week!) to the center pole, where I'll gather the arrays into combiners and make the heavy cable run to the house.

Right now, the foundation has a 2" SCH80 sleeve poured in there for the URD, is this big enough for both URD bundles? It's only a sleeve/sweep to get the URD from underground to the side of the pole/junction box.

If not, what size would I need to put both bundles in a single conduit? Otherwise I'll look at getting a 2nd conduit for the 2nd bundle.

[mike95490]

not completly related to your condouit question, but I'd located some terminal blocks and covers, rated for alum wire
http://www.elecdirect.com/catalog/04ce3721-36d8-402e-b6d2-37ec306c702a.aspx
which worked better for me at one junction, than the split bolts did. And their prices & delivery were good too. Needs good screwderivers and allen wrenches to get torque set properly, and I've discovered there is flamable and non-flamable anti-ox goop for alum wire.

[dwh]

I am installing 3 polemounts, and am running 2 sets of 4/0 AL URD (per my PV electrician, I'm doing the trench work, he's doing the electrical, but in Hawaii this week!) to the center pole, where I'll gather the arrays into combiners and make the heavy cable run to the house.

Right now, the foundation has a 2" SCH80 sleeve poured in there for the URD, is this big enough for both URD bundles? It's only a sleeve/sweep to get the URD from underground to the side of the pole/junction box.

If not, what size would I need to put both bundles in a single conduit? Otherwise I'll look at getting a 2nd conduit for the 2nd bundle.


You didn't specify the the number of conductors, just "sets" or "bundles".

If by bundle you mean a cable that has 2x4/0, 1x1/0 and a ground, then no, you can't run two of those in a single 2".


Here's a thread on the Mike Holt forums that talks about URD:

http://forums.mikeholt.com/archive/index.php/t-59273.html

[Dave Sparks]

And he did not say the distance which as anyone who has done this kind of work will want to know. It is the key, well next to the inspectors requirments!

Use as big of conduit as you can if you don't know is a great fallback!

It probably is too late to ask why the design required this large wiring but...

[mike95490]

Having just pulled 3 wires of #6 alum, thru 900' of 1" conduit, it was a bear, and the tables say I could have pulled 4 wires. I'm suprised I didn't end up with an extra 200', I'd swear the wires should have streached as hard as we pulled with the bucket of the tractor. (gotta pull straight up)
Go larger conduit if it's not too late.

--
http://tinyurl.com/LMR-trenches

[HuckMeat]

Thanks for the input! This is only a sleeve (not a full length run) so the pulling isn't the issue, just how conduit fill requirements are applied to a bushing/sweep exiting the ground; I'm running URD direct burial, bedded in sand. I've another conduit for future work, but my electrician recommended URD in sand for cost reasons.

The cables are upsized for minimizing voltage drop (220' run) and additional capacity in the future. A single 2x4/0-2/0 URD would probably meet the current design, but as long as I have a trench open, I'm putting stuff in there, including an extra conduit. It's a grid interactive system with outback GVFX inverters and MX charge controllers.

If the midnite classic ever came out, I'd probably save enough on wire to pay for it... Alas, I can't wait forever. :)

The 2" sch80 sleeve is already in the polemount foundations, but sistering another up still puts the two conduits within 8" of each other, and close enough to bring it all into a single junction box, which I'll have anyway. I'll just bring one through each conduit, since the conduit fill calculations still work there.