Underground Conduit Bend Limit

[localhost]

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 the run?

[N8N]

sounds like some of the bends in this run is an elevation change, can you just dig the whole thing deeper so you don't have to 90 around the retaining wall? If you can't, can you use 45's?

nate

[dpb]

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).

--

[Jerry]

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

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.

[Ralph Mowery]

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.

[RBM]

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

[John Grabowski]

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.

[Terry]

Consider using underground cable instead of conduit

[localhost]

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.

[gfretwell]

The only down side is UF has to be 24" down, conduit could be 18". If this is a short shot and fairly easy dig an extra 6" is not that big a deal