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20 years ago
Pulling *wires* through conduit is easy. You were pulling a *cable*. You had a lot of factors working against you:
a) First and foremost, Romex cable is composed of *solid* wires. There just isn't a lot of flexibility there. Especially in 10-gauge. It's much easier to pull *stranded* wire.
b) Bundling wires together in a cable reduces flexibility still further. It's much easier to pull four individual wires than one 4-wire cable -- even if you wrap them together at the point where you attach the fish tape, and pull all four at once, it's still easier than pulling a cable.
c) Cable sheathing isn't especially slippery either. THHN/THWN wire has a hard, slick outer layer that makes it positively glide through a conduit.
d) Romex tends to twist up as it's paid out, which compounds the friction and flexure issues.
e) Were you using a wire-pulling lube on the cable?
f) How many pull boxes did you have in the middle of this 75-foot run? It's probably overkill, but I usually install a pull box every two or three sections of conduit. It makes life much easier.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
I'm cheating. I'm doing individual wires and assembling the conduit over the wire and mounting it - slide on a section, bolt it down, etc. I'd hate to charge by the hour to do it this way, but its easier on a guy with back problems. :-)
Bob
It's not really legal, but again, I doubt the wiring police will be knocking on your door. In fact that is how FPL runs long service laterals here. I see it all the time. The code assumption is any raceway system is built such that the wires can be pulled in and out at any time. That makes a lot of sense in a commercial setting but the code is a "one size fits all" affair. When I asked my boss how I should use 90-4 (the inspector discretion clause) he said "just make it safe". Your method is safe IMHO.
You should be using individual wire, not romex. As a matter of fact, there is something in the code that reduces the amount of wire that can be used if it is romex, as I recall, but I don't remember exactly what it was. Temperature rise, or something.
Power lines should be buried at least 3 feet.
Actually, then end result will physically be the same as if I had run the conduit and pulled the wire through it. I just happen to have the luxury of being able to put up one 10 foot section of conduit at a time because the run is not that long (70 feet). I'll have pull boxes and two 90 degree bends in the conduit. I just don't want to pull it because of my back.
I appreciate your practical comments.
Bob
Cables pulled into conduit has to be computed as a conductor using the widest dimension as the diameter. If you twist the cable a few times the widest dimension IS the diameter. 12-2 Romex won't "fit" in 1/2" conduit because of this. If you have ever tried to pull it through a few bends you would agree. Most inspectors will ignore this for short sections of conduit used for supplimentry protection, like down the wall of your garage or shop. 3 wire with ground is usually smaller than 2 wire in the computation since it is closer to round with a smaller diameter.
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