I have to run a #6 wire to the garage through PVC conduit underground.
The problem is that I can't come up with no way to run the conduit
without going over the 360 degree bend limit.
The conduit goes through the cellar floor, nineties horizontally,
nineties vertically below a retaining wall, nineties horizontally
underneath the retaining wall, nineties east to the garage, then
nineties up vertically through the garage floor. That gives me 450
degrees. The total run is around 70'.
Is there an external box I should be looking into so as to split up
If this is being trenched so have access, no problem -- just put a
covered (burial-rated, of course) elbow at a couple of the intermediate
locations from which to make the pull.
Could quite possibly eliminate a couple of the elbows bends by boring
thru the wall instead of diving under (or make the run up to that point
deeper or slope instead of a sharp bend).
I think the bend rule is for actual bends in the conduit. Are you using 90
deg elbows or just bending the conduit ? If using the 90 dge elbows they
should have a cover plate for pulling the wire.
The 360 rule for bends would start over at each 90 deg fitting that has the
cover for pulling the wire.
No, the factory bends count in 360 degree calculation. Also 90 degree
elbows as you call them do not have access plates and if they did they
would have to accessible and could not be buried.
One way to solve the problem and remain legal is to install and
underground box. Look at slide 111 at http://electrician2.com/2005nec1/2005_nec_files/frame2.htm
The nonmetallic boxes are not that expensive or you can build your own
using concrete. Another way is to go direct burial from your house to
the garage and use USE conductors.
I believe the max is four 90 degree bends, unless you use pull fittings or
boxes, and of course they must be accessible. Be sure to use wire rated for
wet locations as well, such as THWN. In some jurisdictions you will also be
required to use expansion fittings
To break up the run you have several options. Put a pull box somewhere in
the middle, but it must be accessible. Use a "C" condulet, but like the
pull box it must be accessible. You can also put a box in the ground such
as a Quazite box which is suitable for direct burial and can be in an area
subject to pedestrian traffic.
Would it be possible to substitute one of the 90's for an "LB", "LR", or
"LL" condulet which would break up the run to stay below 360? These would
also have to be accessible.
One of the nice features of PVC is its flexibility. Would it be possible to
curve the run of the conduit enough to get where you are going without using
all of those 90's? Maybe use some 45's with the curve of the conduit.
Thanks for all the responses.
I'm going the UF route. Conduit would be useful if a re-wire was ever
done, but given the many turns, buried box, and relatively short
distance, underground cable makes more sense.
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