Expert: David Coil/C. R. Construction - 8/9/2005

Question
I have 1" PVC conduit installed and want to run (3) 6 Gauge and (1) 8 gauge ground out to a subpanel. I need to run 100 feet from one side of the house to the other. I was going to feed the sub with a 60a breaker.

I checked to see how many wires can fit in 1" conduit and it looks like it shows (7) 6 GA wires can fit. There is plenty of room to fit 4 wires in there. I think you could even fit 4 gauge in the 1" if you had to.

Why would you not want to fill it all the way? Does heat become an issue?

Also, Can I run utility cable that is 3 conductor that is sheathed (with ground) or should I run 3 cables plus a ground?

Thanks

Answer
Heat is the all important issue.  The utility cable you refer to is for open air runs...thru attics and crawl spaces.  Consider the "air" in a conduit run.  The wire needs to breathe.   Depending on the size of wire...conduits are supposed to be filled 40% or less of the conduits cubic inch area.  If you have bends, this increases the friction element of the pulling the wire thru.  Large pipe and smaller wire are prefered.  You have the minimun conduit and the maximum wire as described.