Wiring 110 and 220 in same box

[Julie Moriarty]

Thanks Julie. As I don't have a cool offset bender, and those minis look easier than trying to execute an offset with my old fashioned ridgid bender, I guess I'll get comfortable drilling anchors.

Box offsets aren't hard to make unless perfect uniformity is required. I flip the bender over and make a quick bend right at the end of the conduit, then flip it 180 and do the same. With practice you can make them all pretty much identical.

Julie,

I was going to challenge you on your limit of 9 current carrying conductor statement, because it's not actually true, but Matt beat me to the punch and said basically what I was going to say. Conduit fill is, in fact, dependent on the size of the conduit. That's the whole purpose of a conduit fill chart. As Matt suggested, you have to consider derating the ampacities. I for one did in fact consider this in my workshop -- as well as considering voltage drop on longer runs. If the derate became an issue (not often), it was just a matter of upping the wire size. Yeah, it costs a little more, but so does having a fire and finding out your insurance won't cover it because your wiring was not to code.

On the whole, derating costs more than installing another conduit. The setup takes more time, wire pulls get harder and trimming out devices can become more difficult. You don't want to have to bring in a tugger to make the wire pull on #12 wires. Poor conduit layout can bring a job to a halt.

I'm no fan of the NEC wire fill max. I've never worked with any electrician who is. We have to pull those wires and know how hard it can be. It just isn't worth it. So most contractors around here, where everything is in conduit, stick with 9 CCCs as the max in any conduit but it's not that often utilized. Many contractors stop at two networks for wire fill. It allows for future additions and is easier to pull on the original.

When I piped my house, I upped the conduit size for home runs and longer pulls with more than 270 degrees of bends in them. It cost a bit more in conduit but it sure made the wire pull easier. When laying out a job I make the conduit install the hardest part of the job so everything after that is progressively easier. My jobs almost always made money. If you don't layout the conduit install right the first time, it can cost you a bundle down the road. The NEC is great as a guideline but following it to its limits can make your life hell. Knowledge of the NEC is only a small part of designing a good electrical installation.

Next time, I'll just say, "My experience tells me this is the way to do it. Take that with as many grains of salt as you wish."

[Chris Padilla]

Thanks for the explanations, Julie. I see the 9 CCC limit is more of a practical limit based on real world experience dictated mostly by economics. Cool stuff!

[Steve Rozmiarek]

Thanks Julie, it's good to hear real word experience. It sure helps my project go smoother, and that's what counts to me. If I can shave a day on installation, i'm woodworking a day sooner.

[Brian D Smith]

Thank you for all the info Julie et al.