Cabling in pro/cable?

Question

does anybody know the formula for figuring out the inside diam of a sheeth or conduit with misc size wires packed into it. any help would be great

Answer 1

You can't tell the ID of a conduit or sheath with merely the number and sizes of individual conductors; there are simply too many variables. The National Electrical Codes do list the number of individual conductors that different conduits may carry, but these are for current carrying conductors; that may be a good place to start.

As for the size of a sheath or conduit, based on the number of conductors ... that's impossible. You would need to know the number of each, of each size, the insulation diameter, whether or not there was any cording in the cable, the arrangement of the individual conductors (twisted pair, etc.) and many other factors. Different arrangements have different packing efficiencies and such.