Practical Limit for Conduit Fill

[tom baker]

OK we know the code allows more wires in a conduit than is practical. 15 THHW's in a 3/4" RMC, which carry a 50% adjustment factor for fill.
With 12, that goes from 30 amps to 15. Seems like the reasonable fill is 7-9 conductors at 70%, that puts you at 21 amps.
I did find a 3/4" RMC with 23 12 THHWs in it once.

 

[HackElectric]

Pull wire in until no more could fit without possibly damaging the wire that is already in there.

Use whatever breaker is available.

Profit.

 

[electrofelon]

Took over a job once where there were 20 - 3/0 CU (100 amp 3 ph feeders, 50% derated) in a 4" EMT. It was a concrete building and there was one existing hole. I guess the previous guy thought it was worth the expensive wire bill to not drill new holes. They even had a core drill rig on site. The same guy screwed up the pipes in the transformer pad so I had to pull 8 400 AL in each of twp 4 " PVC...

 

[sparkyrick]

I once did a remod to an ice cream shop and all the panel homeruns were 1/2" EMT with eight solid wires in each them. The entire job didn't have a stick of 3/4" anywhere!