So far I have run 3 new circuits from the breaker box on one side of the
house to the workshop and garage on the other. I have to run a 4th.
What hole size is recommended for 10/2 in floor joists? I alway drill the
smallest possible hole to minimize weakening the joists and then pulling the
cable is an ordeal.
Is it necessary to keep the holes any distance from existing holes, or am I
making too much out of this?
Best to drill joists in center of the joist depth, never in the center
1/3 of the span and 6" or mare from the bearing ends
Max hole size is 1/3 the joist depth & min edge distance is 2"
Section R502.8.1 Sawn Lumber:
"The diameter of holes bored or cut into members shall not exceed
one-third the depth of the member. Holes shall not be closer than 2
inches to the top or bottom of the member, or to any other hole located
in the member. Where the member is also notched, the hole shall not be
closer than 2 inches to the notch."
Now as to multiple holes...hmmm... a single large hole would easilt
accomdate all but not after they're already there. :(
If you're gutsy, careful & lucky you could enlarge an existing hole
with the wire still in place OR remove the wire & hole sawa bigger
hole OR just drill another hole....I'd want at least 2 or 3 hole
diameters of "meat" between the holes...if my thinking is correct 1"
holes could be drilled 3 or 4" apart (min) seems resonable
IMO the single large hole is looking better & better
this code passage says 2" minimum "meat" between holes...my concept
depends on hole diameter...I like mine better...... code passage
allows 3" holes in a 2x10 with only 2" of meat between them ...that
makes me nervous
Thanks, my holes are only like 3/4" so I seem to have a pretty big safety
Yeah bigger holes would have saved a great deal of work, but so would a
subpanel in the shop. But those boats have sailed.
Though maybe not; perhaps I should bit the bullet and replace one of the
12/2 cables with a 8/3 to a subpanel. It is too late at night to be
thinking about such things.
You do not want to pull more than one cable through a hole;
theoretically the currents in any given cable sum to zero but if you are
pulling a LOT of current and there's a cable smack up against another
one, you could get some induced voltages.
replace "fly" with "com" to reply.
Wouldn't that imply that everyone is getting lots of induced voltages
at the load panel where all the circuits meet and some are "smack up
against another" as they run into the box? I have a some romex
connectors with 2 and 3 circuits passing through them into the box.
Would the very short distance of "smack up against another" in these
cases make the induced voltages negligible?
Nate Nagel wrote:
True, in theory. And in practice in some places, homes not being one
of them for typical home wiring, which is, I believe, what the OP is
The amount of induced voltage in home installations is irrelevant and
can be ignored, as evidenced by MANY power cables sharing MANY holes
with impunity in every home I've ever lived in.
"Trust me, there is NO way to nonchalantly conceal the fact that you have a
power tool in your head, no matter what you do." -- El Gato
That's for sure. If just having one AC cable next to another was a
problem, there would be a lot of screwed up houses, including new
constructions. Any induced voltage is going to be so small that it's
nothing compared to the fluctuations caused by normal powerline
transients, turning on/off large loads, etc.
I usually drill 5/8" holes for 14/2 and 12/2 wiring. I think 10/2 wiring
fits too, but it has been a while since I wired our house. You could easily
switch to 3/4" if needed. Basically, the hole should be big enough for the
wire to pass through easily without binding or damaging the cable sheath.
Anything bigger just weakens the joists/studs.
Still, if you have lots of wiring to run, it's easier to drill a bunch of
equal sized holes, even if you're running different cable sizes. This also
lets you buy a good quality self-feeding auger bit, instead of a bunch of
cheap bits in multiple sizes.
I only run one cable through each hole and try to space multiple holes at
least 4" apart (center to center). Try to drill your holes in the center of
the joist (vertically) when possible, and never near the upper or lower two
inches. Space multiple holes along the length of the joist, not on top of
each other vertically.
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