It seems like I've gotten 95% of it figured out, but it is that last 5% that's causing all the problems.

The plan is to have aluminum conduit across the garage roof, to the conduit penetrating the roof down to the garage ceiling, but maybe stopping in the mechanical room. The one problem is that maybe two pieces of aluminum conduit would need to be threaded, but I'm working on avoiding that somehow.

So the big questions now are can the conduit be run across the roof, with a 90° bend and down through the roof with everything connected? The other factor is that the garage roof is slightly higher than the roof being penetrated, so there will be some conduit above the roof to get to the garage roof height.

Can it be run like the utilities do with a weatherhead on the conduit penetrating the roof? And does the weatherhead only accept a certain number of a certain guage wires, or can you get other inserts for it? And what about the short run of unprotected wire that is left hanging exposed? How can that be protected?

And finally, what is the best way to seal the roof penetration? It seems that Lowe's has something with a rubber insert that is cut to the size of the conduit, would that be OK? Or is there a special flashing just for conduit penetrating a roof that a roofer can get?

I used metal outdoor work boxes, like what is mounted for outdoor lights. For a seal, just used roofing cement plastered the bottom of the box and srewed to the roof decking. All roof wiring is exposed USE2 just tie-wrapped to the frames, this enters the work box with the compression threaded with the rubber grommets , spliced to TWTH in the box with runs to the conduit

As for the penatration, I used a hole saw, 1" hole. The bottom of the work box is threaded, so I have a threaded to EMT adapter then emt thru the hole, well I used a short 90 deg emt to the threaded adapter to metal box, all installed from the outside and slipped thru the hole.

Everything from home depot

Hope this helps

SG

I've started using this product:http://www.rstcenterprises.com/pdf/soladeck_brochure.pdf for the on-roof electrical junction box. In fact, in the last install we did (2 strings so no fuse breakers necessary), we hid the box under the panels. Used a short piece of threaded metal pipe through the roof, switched over to flexible metal conduit to come down from the roof into the attic space and then over to emt to run to the inverter or DC disconnect. I personally don't like the look of conduit running outside on the roof.

Scott.

Edit: I've attached a picture of the Soladeck in use. Sealcon threaded connectors for the USE-2 and ground wire to enter the box, ILSCO wiring lugs to not only combine the 2 strings but also transition to THHN-2 wire.