How many holes in studs


Old 01-02-07, 07:36 AM
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How many holes in studs

Just a quick question about boring holes in studs & running wires. How many 7/8" holes can I bore in a 2x6 & 2x4 load bearing stud? In my kitchen I might want (2) or maybe (3) in some of them. I was planning on running my small appliance circuits in one set of holes (2) 12/2WG & my electric range & microwave circuit in another.

How many 12/2WG cables can I run through a 7/8" hole without derating?

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Old 01-02-07, 02:10 PM
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I'm no engineer, but I'd not drill through those studs, or use smaller holes, spread out.
Old 01-02-07, 04:12 PM
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Not drill the studs? How does he get the wire through them?

A guide I have says no more than 40% drilled in a load bearing stud. This means a 1 7/16" hole can be bored in a 3.5" load bearing stud.
A non-load bearing stud, and load bearing under certain circumstances, can be drilled to 60%.

The diagrams I have:

"Diagrams comply with the
requirements of the three major
model building codes: Uniform
(UBC), Standard (SBC), and
National (BOCA), and the CABO
One- & Two-Family Dwelling
Old 01-03-07, 03:40 AM
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How many cables through a single hole is open to debate and pretty much something you ought to visit with the inspector about.

Technically, derating with cable takes effect when the cable is bundled. Bundled implys the cables are tied together somehow, like with binding twine or tie wraps for 2 feet or more. Inspectors often insist that cable run through the same set of holes for several feet are bundled even though they are only in close contact where they go through the holes. In any event, using the standard derating tables in the NEC you should be able to run 4 - 2 or 3 #12 or #14 conductor cables through the same hole.

Ease of installation and preventing damage to the cable sheath also suggests 4 cables max based on my experience. Also, if the range cable is significantly larger than the other cables, like a #8 or #6, it is often best to run it separate as the smaller cable will tend to work itself under the big cable as it is being pulled and will consequently pull hard, sometimes wedgeing itself a bit.

As a general rule I run 3 cables to a hole most of the time, just a personal preference.

Petey's info on boring the studs is right on. However, since the NEC requires a steel protection plate if the hole is closer than 1 1/4 inch from the edge anything larger than a 1 inch hole bored dead center in a 2 X 4 would require a plate, A 3/4 max dia hole "about" in the middle generally works out well for most things. A 7/8 is OK if you're careful.
Old 01-03-07, 04:00 AM
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Thanks Unk. I did get the boring specs but I shouldn't have left out the nail plate info.
Good catch.
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