I'm looking into running new electrical circuits to my attic and second floor. The attic is two bedrooms + a small bathroom, the second floor is four bedrooms + another bathroom. I'd like some advice on how many circuits to run. My thought is one lighting and one outlet circuit for each bathroom. Then one lighting and one outlet circuit for each floor. So a total of eight circuits. Probably all 20amp.

I can access the second floor by fishing down from the crawl space next to the attic rooms. The house was built in 1911 so the walls are nice big open cavities, which seems to make fishing wires a bit easier, but I'm still going to need to open the walls and I want to avoid that as much as possible. Is there any limitations on how close I can run wires. A little googling suggested I could only "bundle" two or three 12/2 cables together, but I could not find any NEC reference for this. If I do bundle three cables together, how far apart must the next bundle be?

I may be limited into only bringing up two bundles (easily) through my walls. If I can only bring six circuits up to the attic how should I break up those circuits? i.e. should I put the bathroom lights on the same circuit as the rest of the floor? or break it up some other way?

  • If in doubt, always check with the Local Authority Having Jurisdiction. There may be local codes and practices as well as national ones. Most town inspectors seem to be pretty willing to answer this kind of question, if you're willing to wait for them to get back to you with the answer. Some contractors are also willing to answer basic questions -- the one I've worked with is very DIY-friendly since he knows this makes me more likely to call him when I have something I don't feel ready to deal with myself.
    – keshlam
    Jul 18, 2014 at 3:09
  • Run a single cable to a sub-panel in the attic. Much easier.
    – Steve
    Jun 8, 2018 at 13:38

1 Answer 1


I'd agree with Keshlam, ask the local inspector about that specifically. It sounds to me like you don't plan on taking out a permit, which I would probably recommend, it gives you peace of mind knowing the job is done right, it's not very expensive, and you can tell the future homeowner when you sell that it was inspected and done to code.

As for circuit design, you said 6 circuits could be a limitation? Then what I'd think about doing is:

  • Both bathroom lights on one circuit
  • Bathroom GFCI Receptacle
  • Bathroom GFCI Receptacle
  • Largest and Smallest bedroom Receptacles
  • Two other bedroom receptacles
  • All bedroom lights (Assuming they don't exceed 12 fixtures)

You probably won't want to have all the lights from one floor on one circuit, as if that circuit ever trips, you'll be in the dark with no supplementary light to guide you.

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