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Thread: House Hunting Electrical Questions

  1. #1
    DIY Member BS's Avatar
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    Default House Hunting Electrical Questions

    My wife and I are house hunting in another state and have found a 9-year old house we like very much. But yellow flags have gone up on two electrical situations. Of course, if we decide to bid on this house we'll have an inspector check these out, but I'd like to get your opinions before we get to that point.

    1. The circuit breaker panel is in a corner of the basement and none of the breakers are smaller than 20 amp. (There are no 15 amp breakers.) But the receptacles in the house are 15-amp receptacles. Is this allowed?

    2. The circuit cables coming out of the panel are run through holes drilled into the ceiling joists. I believe the joists are 2x10 and span 12-14'. There are 7 or 8 holes drilled side-by-side about 2" up from the bottoms of the joists, starting about 6" from the concrete wall that supports the ends of the joists. Is this a cause for concern? I had always thought that holes should be drilled in the middle of the joists. (I took a photo but didn't bring the cable to allow me to download it to my laptop and attach it here.)

    Thanks in advance.

    - Bernie

  2. #2
    Plumber jimbo's Avatar
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    1) No problem. This is a very normal set up. It is allowed to put 15 amp receptacles on 20 amp breakers. The wiring undoubtedly is 12 guage, adequate for the 20 amp breaker. The idea is that it is not necessary for each individual receptacle to be 20 amp rated, as very few devices found in the home require that. But by making it a 20 amp circuit, you are less likely to run into trouble when a lot of items.....computer....etc.etc. are plugged in the same room/

    2) Not sure about that.....waiting for input from others.

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default holes

    How large are the holes? If they are individual ones, they are probably very small in which case the location should be imaterial.

  4. #4

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    2. The circuit cables coming out of the panel are run through holes drilled into the ceiling joists. I believe the joists are 2x10 and span 12-14'. There are 7 or 8 holes drilled side-by-side about 2" up from the bottoms of the joists, starting about 6" from the concrete wall that supports the ends of the joists. Is this a cause for concern? I had always thought that holes should be drilled in the middle of the joists. (I took a photo but didn't bring the cable to allow me to download it to my laptop and attach it here.)

    The middle third of the joist should NOT be drilled. The holes can be a MINIMUM 2" from the edge and 2" apart and should be no larger than a third of the joist (about 3" for the 2 X 10). Sounds like you are OK.

    I have a paper from the "American Forest And Paper Association" about 40 some odd pages w/ nicely done pics/diagrams in Adobe. If interested- I can find the link or E-mail it to you.

    Richard

  5. #5
    Jack of all trades frenchie's Avatar
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    Default

    Just so we're clear - there's notches, and holes. Holes can be anywhere along the length of the joist; but notches must be near the ends (none in the middle 3rd of the span).

    Holes can be up to 1/3 of the joist depth, no closer than 2" to the top or bottom edge. If it's closer than that, it's a notch - which are limited to 1/6 of the joist depth.

    Translation:

    On a 2x10 joist, the hole cannot be any bigger than... about 3 and 1/8 inches across. (a 2x10 is actually 9 5/8, so it gets a little confusing with the fractions)

    It also has to be at least 2" away from the top or bottom edge of the joist.

    If it's closer than 2" to the edge, it's a notch. Notches can't be any bigger than... about 1 and 1/2 on a 2x10. It also has to be near one of the ends; it must NOT be in the middle 1/3 of the span (length of the joist).

    If you have a series of holes, they have to be at least 2" apart.
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  6. #6
    DIY scratch-pad engineer leejosepho's Avatar
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    An I-beam or I-joist can help illustrate some engineering principles here, and those principles are essentially the same for regular framing joists.

    A load sitting on top of the joist stresses the upper portion (1/3) or flange, and the center portion (or web) then passes some of that stress along to the bottom third or flange.

    Just as the webs of steel I-beams can be perforated to save material, reduce weight or to make room for electrical or plumbing runs, a joist can also be "perforated" (drilled) for mechanicals anywhere within its middle-third "web".
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