#4 awg and larger in conduit bodies?

TwoBlocked

TwoBlocked

Senior Member
Location
Bradford County, PA
Occupation
Industrial Electrician
So I was looking at the chart for conduit wire fill shown in the first link. I noticed that a 2" LB67 can carry only three 1/0 conductors, but a 2" LL67 or LR67 can carry six 1/0 conductors. That seem counter-intuitive, especially comparing 2020 NEC 314.28 (A) (2) exception, with the second link with the conduit body dimensions.

What am I missing? Everything being equal, I'd much rather run wires into an LB than an LL or LR.


 
TwoBlocked said:
Well they may think so, and I won't argue with them, but what about 2020 NEC 314.28?
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See 314.28(A)(3). That is the section that tells you can install the size and number of conductors marked on the conduit body without regard for the dimension requirements.
However, assuming the same distance between the conduit entries on the LB and LR/LL I have no idea why the fill for the LB is smaller.
 
don_resqcapt19 said:
See 314.28(A)(3). That is the section that tells you can install the size and number of conductors marked on the conduit body without regard for the dimension requirements.
However, assuming the same distance between the conduit entries on the LB and LR/LL I have no idea why the fill for the LB is smaller.
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I see ... I had a hard time understanding what (A)(3) was saying. I'm afraid when things get wordy, I guess (or hope?) they don't apply to what I'm doing.

And running it through my mind, yeah, I guess I could get more or bigger wires into an LL or an LR than an LB by using the handle of a screwdriver and a hammer to pound them in, and get them to stay pushed between the sides of the conduit body while I get the cover on. With an LB, they tend to bulge out. Not how I like to do things, but I can see it.

Thanks for the clarification, Don!
 
I wish they would do away with max size wires in a conduit body and just leave it up to common sense and to equate with the conduit fill.

While I’m griping the cu inches in form7 fittings seem so conservative. But I guess numbers don’t lie.
 
40 some years ago we were installing a leveling line for steel coils in a plant. We were running some 4 inch with big conductors going in. My buddy was pulling with a winch and I was guiding the wire into a conduit body. I got my hand pulled in while trying to get the wire to lay nice. Sucked my middle finger of my right hand into the conduit. I ended up at the ER that night and I still have the scar from where it tore my nail out and all the skin to the first joint
 
Dsg319 said:
I wish they would do away with max size wires in a conduit body and just leave it up to common sense and to equate with the conduit fill.

While I’m griping the cu inches in form7 fittings seem so conservative. But I guess numbers don’t lie.
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My reading of 2020 NEC 314.28 (A) (1,2,&3) may be wrong, but I get the idea the manufacturers are given a free ticket when it come to conduit bodies. The three paragraphs in (3) read more like exemptions, than rules. Minimum bend radius is thrown out the window, as long as the fill is less than required and there is a marking on the body.
 
TwoBlocked said:
The three paragraphs in (3) read more like exemptions, than rules. Minimum bend radius is thrown out the window, as long as the fill is less than required and there is a marking on the body.
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I would assume that there is some formula or testing involved when they determine the maximum conduit body conductor size and number of conductors. Is there a minimum bend radius for single conductors?
 
What I am referring to is the second paragraph of 2020 NEC 314.28(A)(3) emphasis mine:

"Listed conduit bodies of dimensions less than those required in 314.28(A)(2) , and having a radius of the curve to the centerline not less than that indicated in Table 2 of Chapter 9 for one-shot and full-shoe benders, shall be permitted for installation of combinations of conductors permitted by Table 1 of Chapter 9. These conduit bodies shall be marked to show they have been specifically evaluated in accordance with this provision."

So, like what conduit bodies have radii like pre-manufactured sweeps?
 
TwoBlocked said:
Then are those the only kind that should be used with #4 awg and larger?
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No...there is no wiring bending radius for single conductors 1000 volts of less. That design simply lets you fill that conduit body to the same fill as the raceway itself.
Conduit bodies marked with the maximum number and size of conductors are fine, but unless you use an oversized conduit body, you can't have the same fill in the conduit body as in the raceway.
 
don_resqcapt19 said:
No...there is no wiring bending radius for single conductors 1000 volts of less. That design simply lets you fill that conduit body to the same fill as the raceway itself.
Conduit bodies marked with the maximum number and size of conductors are fine, but unless you use an oversized conduit body, you can't have the same fill in the conduit body as in the raceway.
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Sorry I am having such a hard time with this. Thanks for sticking it out. 314.28 (A)(2) is titled "Angle or Upulls, or Splices." How can this not be about bending radii?
 
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