I've used this site a great deal for guidance, so thanks to each of you in advance!

I'm getting ready for my Rough In Elec Inspection in MN for a 900 sq ft basement finish with 7'10" suspended ceiling. Just wanted to run my setup thru the experts and see if anyone sees anything I might want to address prior to R/I.

I have 5x20A feeders running thru individual 12g THHN (5xhot + 5xneutral + 1ground) inside of 3/4" EMT from Garage (circuit breaker) to basement (36ft run). Once in basement, conduit continues 3 ft to a 6x6x4 box mounted to rafter (above suspended ceiling) where I brake out to 5 romex 12-2.

Circuit list:
I have 8 standard cans + 1 cieling fan/light on circuit 1
7 standard cans + 1 porcelin rough-in light on c2
8 standard outlets + 2 counter heigt gfci (future wet bar on the end of c3)
10 standard outlets on c4
bathroom (1 light/fan + 1 vanity light + 1 outlet) on c5

My concerns are mostly around the feeder circuits and the 6x6x4 box installed about the suspended ceiling, although I've read many times in many places this is fine. Also, I'm not sure I fully understand the "derating" which can occur when running feeder lines in conduit. Finally, I was told 5 circuits using 1 common ground was fine in 3/4" emt... I hope that's right!

Thanks!

During the rough inspection, I doubt the inspector will care about how the devices and lightss are circuited. He will more look at the actual installation of wiring, boxes, splices, etc, to be sure it meets code.

He will ask about Arc Fault and GFI protection for certain areas.

He may be interested in how the derating was done for the 5 circuits in conduit. You now have 10 current carrying conductors in a conduit, which now need to be derated 50%. If you used #12 copper with THHN insulation, each is rated 30 amps (for derating purposes only), and now each can only carry 15 amps. If you have 15 amp breakers for each circuit, your done.

You mention 20 amp circuits, which is what they probably need to be, so I assume you are using 20 Amp breakers. If this is the case, the inspector should ask for #10 wire to be installed.

In a home, and only 36 feet, I doubt he will push the issue.

The one equipment ground for the 5 circuits in conduit is fine, So is the junction box above a suspended ceiling.

Tkrussel,
Thanks much for you time/answer. I've held off purchasing the AFCI breakers until I talk with the inspector to see if he's going to enforce the 15A circuits or if he'll allow 20A. I've appropriated for 15A if necessary (biggest circuit has 8 cans + light/fan) which should be just w/in expected load on a 15A (using the 1.5A per term sizing method). Also, since the conduit will run directly into the breaker box he'll be OK with me leaving the couduit/wire a couple feet short of the box for the R/I and then running it into the box when I connect the circuit to the breaker, right? (I have 2 small children which have access to the breakerbox in the garage and I do NOT want to leave the cover off the box, nor leave wires loose in the box with the cover on.) finally, when am I allowed to make the feeders live? After R/I or do I have to deal w/ extension cords until final inspection (after sheetrock/suspended ceiling)?

Thanks again!

I would have the wires pulled into the panel terminate the neutrals and grounds, and cap the wires to be terminated onto breakers.

Energizing the wiring can be done when all devices, light fixtures, etc are installed. Depending on Certificate Of occupany rules in your area, some inspctors will not allow systems to be used until final inspcetion.

Thanks much tkrussell!

Be sure you used solid conductors for grounding. If you used Stranded(thats what I use), then connect the grounds to a solid pigtail.
There is a Note in the code book that allows energizing circuits for "experimental and developemental" purposes.
I use that all the time, especially recessed cans where it is easier to fix a connection without the ceiling in place, 4 inch cans are difficult to work through the small opening.
You have all your Phone, Computer, Alarm, Intercomm, Speakers, or water ran everywhere?
Since this is a Suspended ceiling, the above problem I mentioned, doesn't apply
Need an outside recepticle(s)? THis is the time.
Good Luck.