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Body Calc

A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
So these C's don't look like they are sized according 314.28. Referring to larger conduits that look like ~3". I'm assuming the larger conduit will have #4 or larger conductors.


1721930847048.png
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
Alwayslearningelec said:
So these C's don't look like they are sized according 314.28. Referring to larger conduits that look like ~3". I'm assuming the larger conduit will have #4 or larger conductors.
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What size conductors are in the raceway? If the conductors are smaller than #4 then 314.28 doesn't apply
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
Alwayslearningelec said:
Not sure but I got ya on of they are larger than #4. Is there any relief to sizing conduit bodies with #4 or larger?
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I don't think so.

(A) Minimum Size.
For raceways containing conductors of 4 AWG or larger that are required to be insulated, and for cables containing conductors of 4 AWG or larger, the minimum dimensions of pull or junction boxes installed in a raceway or cable run shall comply with 314.28(A)(1) through (A)(3). Where an enclosure dimension is to be calculated based on the diameter of entering raceways, the diameter shall be the metric designator (trade size) expressed in the units of measurement employed.


1) Straight Pulls.
In straight pulls, the length of the box or conduit body shall not be less than eight times the metric designator (trade size) of the largest raceway.
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infinity

infinity

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Location
New Jersey
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Journeyman Electrician
Those can be used to pull in the pulling rope or a tru-tape but that's about it. I've seen it a hundred times where guys use C conduit bodies on big pipe to satisfy the 360° rule and they have no idea that they're not code compliant as a pull point.

Looks nice too. I love the fact that they put the covers on during the installation and left them open. I always insisted that my guys do that so the cover is already there.
 
A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
infinity said:
Those can be used to pull in the pulling rope or a tru-tape but that's about it. I've seen it a hundred times where guys use C conduit bodies on big pipe to satisfy the 360° rule and they have no idea that they're not code compliant as a pull point.
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Doesn't that get flagged or doesn't the engineer need to approve?
 
don_resqcapt19

don_resqcapt19

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Location
Illinois
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retired electrician
infinity said:
In my experience no one really cares. Most of the time with big conduits you pull through 6, 7, or 8 90's with the pulling machine.
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The inspectors that I know will flag that as not having the required pull points as the C does not qualify as a pull point. Yes, I know we typically pull through more than 360 degrees of bend in the real world.
 
don_resqcapt19

don_resqcapt19

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Staff member
Location
Illinois
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retired electrician
infinity said:
Those can be used to pull in the pulling rope or a tru-tape but that's about it. I've seen it a hundred times where guys use C conduit bodies on big pipe to satisfy the 360° rule and they have no idea that they're not code compliant as a pull point.

Looks nice too. I love the fact that they put the covers on during the installation and left them open. I always insisted that my guys do that so the cover is already there.
Click to expand...
That is a great idea, but why not close them up so you can blow strings without getting to the fitting?
The plant I did a lot of work at specified Form 7 conduit bodies, so I did not have the option of putting the covers on like that.
 
don_resqcapt19

don_resqcapt19

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Illinois
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retired electrician
Note that the same issue exists with LBs. With larger conduits and conductors, you have to use very expensive LBs to comply with 314.28. We would often use 3 or 4' length of 6" wireway as an LB because it gave you more room and was cheaper than the correct LB.
 
don_resqcapt19

don_resqcapt19

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Location
Illinois
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retired electrician
Alwayslearningelec said:
The guys will pull 500 or 600 mcm through 5+ 90's?
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Not uncommon. However whenever I did that, I ran the pulling calculations for both the pulling tension and the sidewall pressure. In most cases the sidewall pressure is the limiting factor. Sidewall pressure is the crushing force on the conductor insulation when pulled around the 90s. It is a function of the pulling tension and the radius of the bend in feet.
 
don_resqcapt19

don_resqcapt19

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Staff member
Location
Illinois
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retired electrician
Dennis Alwon said:
I am talking about the tension on the wire. Certainly could be an issue with smaller wires..... IDK
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The tension is rarely the limiting factor when pulling large conductors. When I did the pulling calculations, the limiting factor was always the sidewall pressure.

On one project with seven 1/0s in a 2" for about 600 feet and six 90s. I changed to 3' radius 90s to get the sidewall pressure within the limits.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
don_resqcapt19 said:
. We would often use 3 or 4' length of 6" wireway as an LB because it gave you more room and was cheaper than the correct LB.
Click to expand...

Even besides the hassle and potential non-compliance of a conduit body as a pull point, in situations where you have like 347 of them like in the OP's picture, seems like a big box or wire way serving a bunch of conduits would be a lot less costly and just easier all around. I kind of generally hate conduit bodies, only will really use them if it's an appearance or a space issue. There's nothing like jumping out of bed in the morning (after having to get up in the middle of the night in the snow storm to go check a GEC to grounded conductor connection) knowing you're going to be pulling conductors in and out of 347 conduit bodies all day 🙄. Kill self.
 
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