Running Wire/Switch?


Old 04-05-05, 01:48 AM
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Question Running Wire/Switch?

I have just started rewiring my house, built in the 30's. I can not find any information for how many 12/2 cables can be run through the same hole in floor joists (basement ceiling). My joists are about 3" or 4" thick by 10" or 12" wide ruff cut. I know you can run more than one cable through a hole, but how many and at what diameter? I am aware of holes not exceeding 40% of stud width, minimum of 2" from the joist edge, and cannot exceed one-third of the joist width. Which is why I threw in the approximate dimensions of my joists.

2nd question, plan on rewiring the master bedroom next to get the window AC unit in and ready for warmer weather. I'm putting in a light switch to run a ceiling fan and maybe one or two outlets (for lighting purposes). This circuit will be 20 amp, arc fault breaker with 12/2 NMB. I know you can put a 15 amp outlet on a 20 amp circuit. Can I use a single pole 15 amp switch on this 20 amp circuit?
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Old 04-05-05, 03:03 AM
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Cables running together through joists must be derated if the are in contact for more than 24". Where the contact is less than 24" you can have as many cables through the stud or joist providing that they span out afterwards.
If the cables are together for a long run you can have about 3x 2 Conductor cables or 2x 3 Conductor cables together this is not including the earthing wire.
Cables carrying heavy loads from dryers and ranges and heating systems would be best put through thier own holes.
Old 04-05-05, 08:40 AM
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It's usually a good idea to run no more than two cables through each hole, and seperate parallel runs by about six inches.

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