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Drilling through Joists

Posted by Jim Bachaud - Around The Sound on February 28th, 2000 03:07 PM
In reply to Cable through joists, whats OK? by Steve C on February 26th, 2000 05:15 PM [Go to top of thread]

NO!!!! DO NOT DRILL THROUGH THE TOP OR BOTTOM OF ANY JOIST!!!!! Ignore everything you may have read about this. The 1/8th rule is good, however. Your holes should be less than 1/8th the size of the joist.

Look at the professional penetrations on any joist in your home. Hopefully, the holes, whatever the size, are drilled through the dead center of the joist. The center of a joist is neutral, while the top is in compression, and the bottom is in tension.

The ONLY safe place to put your holes is in the middle. This applies for everything except plumbing waste lines, and that is strictly due to flow issues. Waste lines should run parallel to joists wherever possible.

As far as sheathed electrical cable is concerned, keep this in mind:
14 guage sheathed electrical cable is only to be used on 15 amp circuits.
12 guage sheathed electrical cable is only to be used on 20 amp circuits.
Do NOT use 14 guage cable on 20 amp circuits for any reason whatsoever. I don't care if it is cheaper or easier to work with.

Do not "Double Tap" a breaker (install a home run to the panel and tie the wire to a breaker that already has a wire coming off of it). If your panel is full, replace a 15 amp breaker with a 15 amp duplex breaker. This will keep you legal when you go to sell the home.

Consider having a professional electrician do your work. The risks you run doing it yourself are not worth your life, or burning your house down, or the life of someone your love.

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