NEC Bend rule for secondary structure?

J

JimFromAustin

Member
Location
Austin, TX
Quick background: Building new house in back yard. This new construction will receive power from utility. There can only be one meter (Austin, TX) The new house must have meter since its closer to transformer. The new house will then feed the existing house 100amps. The diagram is:

Utility--------> Meter --------> New House cutoff ------> New house panel
................................................ |
..................................................V
..................................................|------> Existing House cutoff -------> Existing house sub-panel


Power is supplied to existing house via PVC underground. Inspector is including bends not created by a machine as part of the 360 count. They are not factory bends. These bends are not dramatic, they are what the PVC will naturally allow.

Electrician says since this is a secondary line, these bends should not be counted. Who is right? You can see an example of one of the bends at the top of the photo.

Thank guys,
Jim


IMG_5068.JPEG
 
A bend is a bend. Factory or field made doesn't change anything. Even long sweeps add up for total degrees allowed. When pulling the cable through the conduit even a slight sweep over the length say of 3 sticks of PVC it will drag of the inside of the curve. Secondary feeds, branch circuits, or service feed it doesn't matter, the total degree of bend is still limited to 360o between pulling points.
 
JimFromAustin said:
Electrician says since this is a secondary line, these bends should not be counted. Who is right? You can see an example of one of the bends at the top of the photo.
Click to expand...

What does a secondary line (whatever that means) have to with the number of bends in a raceway? A Fred stated all bends count towards the 360° limit.
 
Inspector is essentially counting a change in direction as 45 degrees. Even for long sweeping bends. Is there a method to calculate the radius (or some other parameter) of the bend and show that the bend may actually be only 15 degrees, not 45 degrees?
 
I see (2) 45° bends in the OP photo.
There may be some small sags and riser in the ditch that I can't see. A sand bottom might help with these.
Allowing for (2) 90° turn ups at each building, I don't see a problem.
 
jim dungar said:
I see (2) 45° bends in the OP photo.
There may be some small sags and riser in the ditch that I can't see. A sand bottom might help with these.
Allowing for (2) 90° turn ups at each building, I don't see a problem.
Click to expand...

There is yet another change in direction beyond what the photo is showing. I don't have any pics available of it. Are you thinking the bend in the top counts as 45? (inspector says trench is good)
 
I see it the same as Mr. Dunger. But if you want to be that precise on the long sweep, you can extend a line for both straight sections to a point that they meet and then measure the degrees of turn. Usually an inspector won't call out on long sweeps unless it becomes blatantly over the 360o.

Minimally I would see 2 45's and would presume 2 90's out of camera field. If there are additional elbows not shown you could have exceeded the 360o. But when pulling I wouldn't really want to pull more than the presumed 270o in the picture.

JimFromAustin said:
There is yet another change in direction beyond what the photo is showing. I don't have any pics available of it. Are you thinking the bend in the top counts as 45? (inspector says trench is good)
Click to expand...
Yes the non-factory long sweep looks to be 45o. How many more bends are there?
 
JimFromAustin said:
Inspector is essentially counting a change in direction as 45 degrees. Even for long sweeping bends. Is there a method to calculate the radius (or some other parameter) of the bend and show that the bend may actually be only 15 degrees, not 45 degrees?
Click to expand...
Yes, it is called a protractor. If you pulled a line along the straight PVC on one side of the bend and a line on the straight part of the PVC on the other end so they intersect, the angle is the angle.
 
I will try to get more photos and look at protractor measurement. Personally, I'm not worried about pulling ever again. If I have to drop a new line, a new trench would be dug. Right now, that garage you see in the photo will be demolished, and then I can easily dig a straight trench. The city of Austin won't allow me to demolish it right now, so I'm stuck trying to figure out another solution which is what you are looking at.
 
I see (3) 90° bends in the post 11 view, i looks like you would have at least one more 90 to go up. I can believe you are just over 360°, what with the bowing in the trench.
 
You definitely got over the 360o. Probably close to 135 over. Cover depth in parts do look shallow. Is this schedule 80? Parts look to be under driveway.
 
NEC allows 360 degrees of deflection between access points whether it be 360x1 degree bends, 36x10, 12 x 30, 4 x 90, 3x90 plus 2x45, 36 x 10....

Sometimes you can get away with more than 360 and not have much issue pulling. PVC generally pulls harder than metal raceways do though. I try to limit myself to no more than 2 90's plus a little natural curvature here or there for runs like this as much as possible and seldom ever go over three 90's if possible. Had a run one time with 4 90's in 2.5 inch with 3x250 and 1x3/0 aluminum and had a hell of a time pulling that one in, and it was only like 50-75 foot run. Would have liked to limit that one to 3 bends but just didn't work out to get it that way because of obstacles. After thought was maybe should at least have run it in 3 inch and maybe it would have helped pull easier to some extent
 
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