maximum footage on a run of EMT

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sparkle

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Does anyone know where in the code it may state the max. amount of EMT you can run (straight) before you have to put a pullpoint/box?
 
A friend of mine teaches a code class, and he is claiming it states somewhere in the code that 100 ft is the max. We were @ work, and I threw the book at him and told him to show me. He could not find it at the time, and now I am very curious!!
 
there is no nec that states a max footage, however, sometimes in the job specs it does state max lengh of conduit run of 100 feet, but it is not a nec requirement.
 
sparkle said:
A friend of mine teaches a code class, and he is claiming it states somewhere in the code that 100 ft is the max. We were @ work, and I threw the book at him and told him to show me. He could not find it at the time, and now I am very curious!!
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He'll spend a lot of time looking. It's never been an NEC requirement.

You're only limited by the fishtape, string or rope you use to pull in whatever length of conductor you can get a hold of.
 
I agree with what the others have said.

This seems to be a common electrical myth. There is no NEC restriction on the length of a run of EMT. There is a maximum amount of bends that can be installed between pull point though.

I have seen engineering specs that limit the length of a run of EMT to 100' between pull points.

Chris
 
You would be limited by the pulling tension, which might fall under the installation & use clause.

A maximum length or size for a given length is implied but not specified by "reasonable limits". One way to take that is to mean the length is limited by the pulling tension.

CH 9 Table 1 said:
FPN No. 1: Table 1 is based on common conditions of
proper cabling and alignment of conductors where the
length of the pull and the number of bends are within reasonable
limits. It should be recognized that, for certain conditions,
a larger size conduit or a lesser conduit fill should
be considered.
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add: and you would be limited by the wire length, of course.
 
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Wow. . I wonder where he thought he was seeing this stuff. . lol
 
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sparkle said:
Wow. . I wonder where he thought he was seeing this stuff. . lol
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There's a lot of 'urban legends' that seem to never die, and no one knows where they come from.

No wire nuts in a panel.... ground rods at light pole bases... ground up/down.... no reusing old equipment... and, like this thread, 100' max pipe run.

They simply will not die.
 
480sparky said:
There's a lot of 'urban legends' that seem to never die, and no one knows where they come from.

No wire nuts in a panel.... ground rods at light pole bases... ground up/down.... no reusing old equipment... and, like this thread, 100' max pipe run.

They simply will not die.
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I agree, it seems these myths keep being perpetuated by people that don't look it up in the code but just stick with the "that's how I was taught" ideals.

Chris
 
I believe if you pull a ground wire, it doesn't matter what the condition of the conduit is, there is low resistance path to facilitate the action of the OCPD.

EMT is not the magical path for 250.118 if other provisions are used. I would be comfortable pulling a quarter mile if neccesary, and allowable per the wire/cable manufacturer's call outs for their conductor(s).

Kill the urban legends!
 
Rockyd said:
I believe if you pull a ground wire, it doesn't matter what the condition of the conduit is, there is low resistance path to facilitate the action of the OCPD.
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I would check out 300.10 and .12 if I were you.. Even if the "condition" is in compliance , as much as 90% of the fault current will be on the EMT and not the wire .

Rockyd said:
EMT is not the magical path for 250.118 if other provisions are used. I would be comfortable pulling a quarter mile if neccesary, and allowable per the wire/cable manufacturer's call outs for their conductor(s).

Kill the urban legends!
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Perhaps not magical,.. just one that offers a lower impedance
 
Perhaps not magical,.. just one that offers a lower impedance
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Over the years EMT will be subject to all kinds of reasons not to the path of least resistance. In addition, current takes ALL paths of return, so if there is a ground wire that is securely attached at both ends, it may very well be what facilitates in tripping of a breaker, or blowing a fuse(s).

Will cb, got to educate my government at the moment (a tea party, the path of greatest resistance!).
 
M. D. said:
. . . http://www.steelconduit.org/pdf/TechTalk_EquipmentGrounding.pdf
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This is a great document. I have used the tables that were first developed at the Georgia Tech by Dr. Sakis Meliopoulos. Dick Loyd was also involved with the setting up and testing to get the results that are published in this book. I think the biggest surprises for me was that the largest fault current return was always very close to the circuit conductors even when multiple paths were available and that most of the current flowed on the conduit when a grounding conductor was in the conduit.

Rockyd said:
. . . if you pull a ground wire, it doesn't matter what the condition of the conduit is. . .
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I am not so sure I agree with that statement, my common sense alarm just went off. I do agree that the 'extra' grounding conductor is a good idea. :smile:
 
sparkle said:
A friend of mine teaches a code class, and he is claiming it states somewhere in the code that 100 ft is the max. We were @ work, and I threw the book at him and told him to show me. He could not find it at the time, and now I am very curious!!
Click to expand...

I hope he has not been teaching this "rule"
 
JohnJ0906 said:
I hope he has not been teaching this "rule"
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sparkle said:
A friend of mine teaches a code class, and he is claiming it states somewhere in the code that 100 ft is the max. We were @ work, and I threw the book at him and told him to show me. He could not find it at the time, and now I am very curious!!
Click to expand...

Maybe the OP is also a judge.
judge.gif
 
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