Multiple circuits in one box?

jdc1040

I'm getting ready to wire an office and have a question regarding circuits. Initially, I was going to run a single 20A circuit for 5 two-outlet receptacles (same ones you find on all the walls in your house). When I got to looking at the specs for the equipment I'm going to put in there, I realized my copier can draw a max of 1090W when copying! Since at the 80% rule I shouldn't stuff more than 1920W on a circuit, that doesn't leave much room for the other stuff going there. So, I was thinking about running its own 20A circuit, but what I'd like to do is run that circuit to one or two of the existing boxes and then have the top outlets be on the original circuit and the bottom outlets be on the new circuit. I'd label the covers so it was obvious which was which. I know I'll have to cut the tabs on the receptacles. Is there anything else that would be wrong with this? Is there anything in the code against running two cables next to each other through the same holes in the studs? Any problems with having two many cables in the boxes?

Thanks for your help.

jbfan

You must use a 2 pole breaker for this set up!

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jdc1040

Even if not using a common neutral? I'm talking about running two entirely separate 12/2 cables.

RST

If you're going to go to the trouble of running another 12/2 cable, why not run a 12/3 cable with a double pole breaker?

But thinking about your suggestion.... you will probably have to upsize the boxes. There are limits to how many current conducting wires you can have in a box (others can clarify this further).

Maybe you could have a dedicated circuit for the copier? You probably thought of that already, but figured I throw it out there...

Robert

jbfan

Yes! Because the yolk of the device will have two distinct circuits, even not sharing a neutral.
I would save some trouble and run a 12/3, but it still must be on a double pole breaker.

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jdc1040

I had thought of running 12/3 with a double-pole breaker, but then I read some articles talking about how it's easy to screw up to where you could create a shorting situation where the wire heats up and starts a fire. I figured it's easier to just stick with what I know how to do (regular old circuits) and not tempt fate. I may still go with a single run just for the copier though.

zpm

There's also the issue of having to use AFCIs, if you are required to and/or care. Are two pole AFCI's even available yet at a reasonable price? Better off to have a 2 gang box and use a duplex recep for each circuit.

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Scuba_Dave

You only need to worry about the 80% rule if you are going to be running continous loads = say 3-4 hours

As Jbfan said: run a 20a 240v breaker (required) with 12-3
There is no problem with running 20a 240v dual circuit run
This automatically puts the loads across opposite "phases" - neutral will not overheat

The problem used to be when single circuit breakers were used & placed on the same "phase"
Instead of the load blancing out across the neutral the load would ADD across the neutral
That's a simple explanation, but basically what happens

I run multiple 20a 240v dual circuits for my Chriustmas display at 90%+ without any problems


You can run 2 cables thru the same hole in a stud
Boxes are rated to hold a certain wmount of wires
How many depends upon th ebox size
If it s a blue plastic box the numbers are stamped on the inside of the box

jdc1040

Thanks for the help! The best options seem to be either running a separate circuit just for the copier or doing 12/3 with a 2 pole breaker as suggested. Won't need AFCI since code only requires it in bedrooms here. The bottom line will probably be how "portable" I want the copier to be in the room. If there's really only one spot I want to put it in, I'll just run it's own circuit. If I might want to move it across the room at some point, I'll probably go with the split receptacles. Thanks again for the help!