I am just finishing up a 5500sq.ft. single story home where I used a combination of NM and 3/4" EMT. I kept close track of costs so I could compare with using all NM. I did it this way because this GC wants most of the wiring in the crawl, not in the attic. It was a nice 5 block crawl and the thought of 4000' of NM and all the stapling in there made me tired all over. The house had a 320A service with (2) 40 circuit ML panels. Out of one panel I ran (7) 3/4" EMT runs to (7) locations spread out in the crawl and terminated in 12"x12"x4" pull boxes. I wired the receptacles and switches in NM through the walls and dropped the home runs into the crawl and terminated in the pull boxes. Each pull box has a EG bar and a laminated card identifying each set of conductors. There isn't more than 10' of NM exposed in the crawl anywhere. Just for kicks I ran all of the crawl lighting in 1/2" EMT. This GC wants a 100W lamp for every 500 sq.ft. of crawl space. Out of the second ML panel I did the same for the workshop and all 240V circuits (A/C, range, dryer)keeping the large loads and motor loads in the separate loadcenter should help avoid flicker-up. This GC is extremely picky. If you do run NM home runs in his crawl he expects you to snap a chalkline and keep all the runs parrallel. He loved the EMT! The network, phones and CATV aren't in EMT but I used bridle rings and it looks sharp. With the cost of 12-2 NM around here @ $155.00 per 1000 and 12 THHN @$56.00 per 1000 plus pulling 1 #10 green in each pipe and using multiwire branch circuits, I came up with a materials savings of just under $750.00. I don't know but I would guess that I saved on labor hours too since I didn't have to spend the time stapling hundreds of feet of NM. I have another home to do for this GC coming up and he wants the same system used on it. I bought several 500' rolls of THHN @ $22.75 before it went through the roof in anticipation of this next house. This was a custom home and it was fun to do. It may be a different story in tract homes where time and money are stretched thin.
