Is 90 degrees the maximum bend?

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I believe a goose neck, or a 100 degree bend is allowed. The code restricts us to 360 degrees before needing a Jbox. But what do the specific specs on the job in question limit you to. On a job I ran for a local gov. the spec limited me to 180 degrees for any pipe that contained #16 wire or larger and then went on to limit the communication conduit to 120 degrees. That just about covered every pipe in the building.

Tom from 26
 
Tom I believe the spec;s yore talking about are for total run... What about a single bend?

Bob, the instructions for that bender say never to bend past 93 (Page 4 and several other places)
http://65.36.183.19/greenlee/im/im1266REV15.pdf
And I can safely assume you have used its dumb cousin where one needs to over bend to accomadate spring back? (usually 2-4 degrees depending on what you're bending intending you to spring back to 90) They do make benders that bend 180's - but they are made for mufflers. ;)

As for a hickey, sure you could bend the thing into a knot - should you - NO.

But as I seem to be the only one of the opinion that you should not bend past a "Quarter Bend" and numbers of 'equivalents' or less - I guess I'll go abuse some other topic. ;) FYI I'm not opposed to putting a .5-90 degree bend 1/100" away from any 90.... But I usually leave room for the shoe...
 
if you can pull it your good to go. i ONCE tried a bend that was not illegal, but it sure was hard to push a steel fishtape through. it was a multi-level offset three point saddle. a modern nylon fishtape would have worked, but i don't know when they were invented. i did this in 1990 as a 2nd year pup.
 
deck work

deck work

The rules are one 90 into the deck then straight to the 90 out of the deck for a total of 180. Dont forget the same rules apply to flexable metalic conduit.
 
e57 said:
Bob, the instructions for that bender say never to bend past 93 (Page 4 and several other places)
http://65.36.183.19/greenlee/im/im1266REV15.pdf
Click to expand...
Didn't see any mention of the sort on page 4... and therefore did not proceed to search for the several other places :grin:

And I can safely assume you have used its dumb cousin where one needs to over bend to accomadate spring back? (usually 2-4 degrees depending on what you're bending intending you to spring back to 90) They do make benders that bend 180's - but they are made for mufflers. ;)

As for a hickey, sure you could bend the thing into a knot - should you - NO.

But as I seem to be the only one of the opinion that you should not bend past a "Quarter Bend" and numbers of 'equivalents' or less - I guess I'll go abuse some other topic. ;) FYI I'm not opposed to putting a .5-90 degree bend 1/100" away from any 90.... But I usually leave room for the shoe...
Click to expand...
The Greenlee 555 Rigid and PVC-coated shoes (catalog page 108) will do 180?'s and I've had several occasions to utilize this feature :wink:
 
peter said:
Iwire,
You wrote: "we occasionally use it when we have stubs sticking out of walls." I assume you meant stubs sticking out of the top of a [steel stud] wall.
Click to expand...
Perhaps he meant "to attach to" stubs sticking out of walls...

shepardshook.gif
 
mdshunk said:
post #9
I think the old book Practical Electrical Wiring might be what proliferated the myth that you shouldn't bend past 90?. That book's been in print longer than most of us have been alive, and it shows a picture of what the author calls a "gooseneck bend" and shows it as being highly discouraged and poor practice.
Click to expand...

I think everybody agrees that there isn't a 90? limit.

Now let's think about the concept of "poor practice".

mdshunk said:
post #9
Myself, I sometimes use a gooseneck bend going into our our of a wall or top plate if I don't happen to have an LB handy. It's formed by making a 120? bend in two shots on the bender, followed by a 30? bend back the other way to make a total 90? transition.
Click to expand...

Scenario A
120? bend
and then a 30? bend back the other way

Scenario B
90? bend, followed by a short straight piece of conduit, followed by a 30? bend in the same direction
and then a 30? bend back the other way

Question #1
Does either scenario have a significant aesthetic advantage ?

Question #2
Does either scenario have a wire pulling advantage ?



Answer #1 is totally opinion and my answer is no.

Answer #2 is definable and testable but also debatable. . My answer would be scenario A. . I believe the short straight piece of conduit in scenario B would increase pulling resistance as the conductors have their bend straightened and then rebent.

David
 
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Smart $
I don't follow this. You seem to have extra bends in there and are using flex [which is terribly bad].

Dab
"i ONCE tried a bend that was not illegal, but it sure was hard to push a steel fishtape through. it was a multi-level offset three point saddle."
I'm not sure what a multi-level offset may be, but the nature of a flat steel fish tape allows it to bend in only one plane at any give time. It won't bend sideways and you have to allow about 4' between bends in diffferent planes.
You are correct that a round tape will bend in any direction but they cost four times as much per foot.
~Peter
 
peter said:
Smart $
I don't follow this. You seem to have extra bends in there and are using flex [which is terribly bad].
Click to expand...
No flex in there. That's just how TurboCAD makes 3D pipe look in bends. Perhaps the following diagram will shed a better light on the matter...

shepardshook2.gif
 
Smart $,
I think I see what you are talking about: the stub outs are horizontal.
But I see a 90? stub out, a 120? bend in the shepard hook and then another 30? to bring the run parallel to the wall. This is a total of 240?.
What I am suggesting is that these runs be planned more completely in advance. For instance, if you knew the run would end up being to the right in your illustration, then you could put in your 90? aimed to the right and then kick it a couple of inches to just clear the drywall. ~10? kick plus 90? = 100? vs 240?.
~Peter

note: degree symbol ? is created by holding down the alt key and pressing 167 on the number keypad.
 
Peter if I use the method you suggest (sweep right, kick out) it would look much better. That is assuming the drywallers don't simply push the pipe back into the wall covering it with dry wall.

I have been at this 25 years and can only remember having to make the gooseneck bend a few times, it's not a way I like to run pipe but it is also not a code violation.
 
e57 said:
Bob, the instructions for that bender say never to bend past 93 (Page 4 and several other places)
http://65.36.183.19/greenlee/im/im1266REV15.pdf
And I can safely assume you have used its dumb cousin where one needs to over bend to accomadate spring back?.
Click to expand...

93 is still 'more than' 90.:smile:

No it's not the dumb cousin. :D

I just checked it again on Thursday....95 degrees no problem with 1.25", try 95 degrees with 2" and I think it will jam up.
 
peter said:
Smart $,
I think I see what you are talking about: the stub outs are horizontal.
But I see a 90? stub out, a 120? bend in the shepard hook and then another 30? to bring the run parallel to the wall. This is a total of 240?.
What I am suggesting is that these runs be planned more completely in advance. For instance, if you knew the run would end up being to the right in your illustration, then you could put in your 90? aimed to the right and then kick it a couple of inches to just clear the drywall. ~10? kick plus 90? = 100? vs 240?.
~Peter
Click to expand...
I'm with Bob in that I avoid using shepard's hook bends as much as possible... and I concur on on his comment on the kick out sweep right method. However, I might add that it would fine if the kick out occurs at a 'rock joint... otherwise, the 'rockers have to notch out their board to get it on and then patch the notch. This is not condusive to the ever more increasing "get-'r-done and throw professionalism out the window" attitude in commercial work.

The method I prefer is to simply put a 4 sq or 4-11 box on the stub and offset out, if need be, the surface pipe run.

I've been on jobs where the preferred method was to subtitute a box for the stub at the top, leaving the box flush with the wall surface and putting an extension ring on it for the bringing in the surface pipe runs. While this method works fine, it inflates both material and labor costs!

note: degree symbol ? is created by holding down the alt key and pressing 167 on the number keypad.
Click to expand...
Ummm... you are using the Male Ordinal Indicator (?) character for a degree sign (?), which is ALT+248 or ALT+0176. For this and other ALT keycodes, http://en.wikipedia.org/wiki/Windows_Alt_keycodes
 
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Is 90 degrees the maximum bend?

The number of degrees in a conduit run between pull points and the maximum degrees in a single conduit bend probably (note qualifier) has less to do with degrees and more to do with the Inspectors gut feeling that the manufacture?s specifications of the cable insulation has not been violated. Cable manufactures create the minimum cable bending radius and the minimum cable training radius and maximum pulling tension so they can guarantee the integrity of their insulation.
 
While it's true that the one-size-fits-all approach of 360? limit doesn't actually fit all, I don't think electrical inspectors have the information or time necessary to correctly combine minimum cable bending radius and maximum pulling tension instead of counting degrees of bend.

Let's say you have a sweep 90 instead of a regular 90. . How much less tension is placed on the cable ? . How many more degrees of bend can be allowed ?

The person that gets the gut feeling is usually the guy running the chugger.

David
 
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