Gradual bends in underground PVC

[Carultch]

I'm looking at the famous "360 degree rule", and I'm thinking about uneaven trench topography and very gradual bends in the run. I'm talking so gradual, that you can make the bend with the room temperature flexibility of the conduit. Possibly 40 ft radius and greater.

Is there a radius at which these bends would no longer count toward the "360 degree rule"?

 

[jap]

This is a question that can only be answered by the inspector looking at your install.
Definitely not any of us.

JAP>

 

[ADub]

Gradual bends in underground PVC

The only angles we measure in ug pvc runs are the 90° stub ups and any factory elbows they may have been used in the run, right or wrong. It boggles the mind that any inspector would look that deep into it.


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[Dennis Alwon]

I'm looking at the famous "360 degree rule", and I'm thinking about uneaven trench topography and very gradual bends in the run. I'm talking so gradual, that you can make the bend with the room temperature flexibility of the conduit. Possibly 40 ft radius and greater.

Is there a radius at which these bends would no longer count toward the "360 degree rule"?

I have never seen anyone get called on that and we do it very often with underground runs. It really does not pull as if there were bends in the pipe. I imagine somewhere there is an inspector who may red tag it. That Gus guy that moderates here is a hard nose-- he would probably tag it... :lol:

 

[Carultch]

I have never seen anyone get called on that and we do it very often with underground runs. It really does not pull as if there were bends in the pipe. I imagine somewhere there is an inspector who may red tag it. That Gus guy that moderates here is a hard nose-- he would probably tag it... :lol:

I could see a difference between deliberately making a broad 90 degree bend and not counting it, vs gentle zig-zag bends because of trench topography.

 

[ggunn]

I'm looking at the famous "360 degree rule", and I'm thinking about uneaven trench topography and very gradual bends in the run. I'm talking so gradual, that you can make the bend with the room temperature flexibility of the conduit. Possibly 40 ft radius and greater.

Years ago in another company where we were all new to this stuff we learned the hard way that one doesn't bury 90 degree conduit elbows.

 

[Carultch]

Years ago in another company where we were all new to this stuff we learned the hard way that one doesn't bury 90 degree conduit elbows.

Any particular reason?

 

[Strathead]

This is a question that can only be answered by the inspector looking at your install.
Definitely not any of us.

JAP>

That isn't really true. Whether we can get away with it can only be answered by the inspector, but the code is clear that it is not ok to exceed 360º in any circumstance.

 

[jap]

Years ago in another company where we were all new to this stuff we learned the hard way that one doesn't bury 90 degree conduit elbows.

?


Jap>

 

[mgookin]

I think you guys mean sweeps.
An elbow is an angle without a radius.
A sweep is a radius which results in an angle.
Agree? Disagree?

 

[jap]

That isn't really true. Whether we can get away with it can only be answered by the inspector, but the code is clear that it is not ok to exceed 360º in any circumstance.

It's exactly true.


JAP>

 

[Strathead]

I think you guys mean sweeps.
An elbow is an angle without a radius.
A sweep is a radius which results in an angle.
Agree? Disagree?

Terminology is a funny thing, but I generally use elbow for standard radius 90's They have a radius though and they are all called elbows in a manufacturer catalogue.

 

[Carultch]

I think you guys mean sweeps.
An elbow is an angle without a radius.
A sweep is a radius which results in an angle.
Agree? Disagree?

I see manufacturer's catalogs that call standard radius bends "elbows", and large radius (24", 36", 48" etc) bends by the name "sweeps".

I've also heard claims that the difference between elbow and sweep is plumbing (elbow) vs electrical (sweep). I initially thought the distinction was field (sweep) vs factory (elbow).

 

[Smart $]

My take is that 352.24 requires bends to be made with identified bending equipment... so sweeps made by flexing the conduit are in fact not bends under Code.

 

[Carultch]

My take is that 352.24 requires bends to be made with identified bending equipment... so sweeps made by flexing the conduit are in fact not bends under Code.

As in they are not allowed at all, or as in they are not required to count toward the 360 degree limit?

 

[Smart $]

As in they are not allowed at all, or as in they are not required to count toward the 360 degree limit?

The latter.

The limit is written as "There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points..."

I take that as only bends count toward the 360 degrees total.

 

[jaggedben]

I could see a difference between deliberately making a broad 90 degree bend and not counting it, vs gentle zig-zag bends because of trench topography.

This best sums up my opinion. If someone deliberately curves the trench so it really goes in a different direction, and the conduit is tensioned to fit to that curve, then I would count that. If they just had trouble digging the trench exactly straight then I wouldn't.

 

[mgookin]

Thank you gentlemen for the clarification on elbow vs. sweep.

 

[GoldDigger]

Thank you gentlemen for the clarification on elbow vs. sweep.

FWIW, a plumbing elbow is far too tight to pull wire comfortably and a plumbing sweep is closer to a conduit elbow.

 

[iwire]

This best sums up my opinion. If someone deliberately curves the trench so it really goes in a different direction, and the conduit is tensioned to fit to that curve, then I would count that. If they just had trouble digging the trench exactly straight then I wouldn't.

You can choose not to count just as easily as the inspector can choose to fail it if it exceeds 360.