Re: Hole Diameter for running cable

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"HLS" <henryhartley@xxxxxxxxxx> wrote in message
news:1164809851.854277.56200@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Robert Green wrote:
> >
> > Thanks.  I'm always reluctant to drill through joists and wonder whether
> > some of the engineers here could suggest what size plywood "cladding"
would
> > offset the loss of structural integrity by drilling 2" holes in 8 or 10"
> > joists.  I've been laying out a CCTV upgrade and with RG6 going
everywhere,
> > the holes add up.
>
> I cannot imagine needing 2 inch holes to run these sorts of wires in a
> home.  I'm assuming that these holes are in the floor joists in the
> ground floor, meaning it is the unfinished ceiling of the basement.

In my case yes, we stripped out the old suspended ceilings and moldy plywood
nailed up without vapor barriers or lots of other good things.

The 2 inch figure represents not only the video cables.  You're of course
quite right about cables being able to be run in a series of smaller holes.
I am installing a new Hayden central vacuum and there are places where I
just have to drill through joists (and in one place it looks as if I can't
avoid the main house beam) and the vacuum pipe is 2" in diameter.  Something
in my gut tells me to brace any hole that large in an old wooden joist.

<stuff snipped>

> While building codes are generally not published on-line, you should be
> able to find out what code applies.  Then you could check to see if your
> local library has a recent copy.

I've always wondered why something as important as building codes are not
available on-line.  That would seem to be the perfect place to gain wide
dissemination.

> For instance, my county uses a slightly ammended version
> of "International residential code for one- and two-family dwellings"
> which our libraries have.
>
> If it were my home (and it was, recently) I'd be inclined to drill 1/2"
> holes somewhere near the ends of the joists.  That hole is large enough
> for two, three or even four cables.  If I'm only running one cable, I'd
> make it 3/8".  If you need to run a bunch though one stretch, you might
> need to increase the hole size to as much as an inch but two inches
> seems excessive.  If an inch isn't enough, then perhaps you need to do
> a bit more planning.  Also, you're better off using a single cable with
> more conductors than trying to fit a whole bunch of individual cables
> in any particular run.

That's great advice for wiring - and probably equally as valid for 2" holes
necessary to run central vacuum piping, at least regarding where to place
the holes to minimize structural integrity issues.  Sorry for the confusion.

--
Bobby G.