Hi Dan,
You can buy plastic electrical conduit. It is a lot like the PEX used for
water. I don't think it comes in 3 inch diameters but it can be had up to about
inch and a half for sure.
pull half a dozen strings through it before you pull it up and you should have
no trouble pulling future wires up the conduit.
They make junctions and unions and all sorts of fittings for the various sizes.
Code may vary a little but usually one bores holes through the ceiling joists
to pull wire through or staple it along the sides. I see no reason why you
wouldn't staple it over the top of the ceiling joists but usually you would not
use the rafter part of the roof member. They then just bury the lot in the
insulation.
----- Original Message -----
From: Dan Rossi
To: blindhandyman@yahoogroups.com
Sent: Monday, September 14, 2009 11:05 AM
Subject: Re: [BlindHandyMan] spray insilation question.
I am planning on having cellulose blown in sometime in the near future.
They said they can use a 3/4 inch nozzle since they will have to drill
through the mortar joints they want to use as small a nozzle as possible.
Not only do they have to drill through the mortar joints, but then they
have to drill through the wood cladding beyond the airgap behind the
brick to get to the voids between the studs.
I may hold off on having the attic done until I do some rewiring first.
I'd rather not have to dig through 12 inches of cellulose to get to all the
fixtures.
Here is a vague plan, and a couple of questions. My house is balloon
construction, so the joist bays run from the attic straight down to the
basement. I've already pulled one set of wires from the second floor
through to the basement. Anyway, I was thinking of trying to find some 3
inch flexible tubing, similar to the 4 inch flexible pipe I used for
drainage around the basement door well. I would run this flexible tubing
down from the attic to the basement in one or two places before having
the insulation blown in, that way I would have a wire chase in place for
future wiring projects. Does this kind of flexible tubing exist? Is
there a reason why I wouldn't want to do this?
Secondly, what is the code for running wiring through attics with blown
in insulation? It seems like it would be a total pain in the ass to just
bury the wiring under the insulation. Can you staple the wiring to the
sloping rafters and then drop straight down from the rafter to the fixture
in the ceiling below? It would make it quite obvious where the fixtures
are, and you could easily see the wiring, but there would be these
vertical wires scattered around your attic. Is that cosher?
--
Blue skies.
Dan Rossi
Carnegie Mellon University.
E-Mail: d...@andrew.cmu.edu
Tel: (412) 268-9081
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