sizing condlets

[bure961]

Can some of you ec and inspectors respond to this post. On conduit runs with tees and lbs how much attention is given to sizing these fittings. I have found the listing inside to be exceeded on the wire sizes .
On one the wire tripped the cb after a few months service.
Thanks for respouses in advance.

 

[kwired]

I have to admit I see violations here quite often and know I have violated it myself many times. Can't really claim to have found any failures due to such violations though, but they certainly can be more difficult to install or remove then one sized properly. Those that don't take precautions to protect conductors from damage are just foolish whether the conduit body is sized properly or not.

 

[don_resqcapt19]

Once you have wires larger than #6, you have to apply the rules in 314.28 to the conduit body. Where the conduit body does not have dimensions that meet the requirements of 314.28(A)(1) or (2), then you look to (3). That is the rule that results in the wire size marking on the conduit body itself. The only issue is that the rule does not provide a way to do a field calculation or use the manufacturer's instructions for combinations of conductors that are not physically marked on the fitting.

 

[augie47]

There has been some controversy here as to the exact approach to condulet fill when the mix of wire you have does not correspond directly with the markings in the condulet.
You can review comments to that effect here:
http://forums.mikeholt.com/showthread.php?t=150840&highlight=condulet

I think that has lead to a potpourri of inspection methods in regard to this rule.
As for myself, I pretty much enforce it literally although I will say that when a conduit "C" has been added to "restart" the bend rule and the wires are actually being pulled straight thru without looping, I have let a few slide. If you are actually pulling out and back in as with an LB, I'm don't waiver.

 

[kwired]

There has been some controversy here as to the exact approach to condulet fill when the mix of wire you have does not correspond directly with the markings in the condulet.
You can review comments to that effect here:
http://forums.mikeholt.com/showthread.php?t=150840&highlight=condulet

I think that has lead to a potpourri of inspection methods in regard to this rule.
As for myself, I pretty much enforce it literally although I will say that when a conduit "C" has been added to "restart" the bend rule and the wires are actually being pulled straight thru without looping, I have let a few slide. If you are actually pulling out and back in as with an LB, I'm don't waiver.

Kind of is pointless to put in an access fitting though when it technically can't really be used for access purposes:angel:

I guess it could be used to squirt in additional lubricant - but so could a explosion proof seal fitting that has even less of an access opening:happyyes:

 

[augie47]

normally where I find them is a run with more than 360? of bends.......
3/4" EMT with 4 #12s, 4-90s and a couple of 45? offsets so the E/C slips a "C" in the run. Kinda difficult for that to raise the hair on the back of my neck whereas
(3) 500s in a 2-1/2 conduit with a Form7 LB will scare me

 

[Patrick_SF]

normally where I find them is a run with more than 360? of bends.......
3/4" EMT with 4 #12s, 4-90s and a couple of 45? offsets so the E/C slips a "C" in the run. Kinda difficult for that to raise the hair on the back of my neck whereas
(3) 500s in a 2-1/2 conduit with a Form7 LB will scare me

my calc shows a 36% fill on 3#500-2 1/2"C, which seems ok.
im guessing the form7 LB is the issue. that bend looks too sharp? i have to look around more for specs and demensions but is that against code? I think i saw somewhere in the nec minimum bend radius per wire size?

---------------------------------------------------------------
Im somewhat new to the field and forums, so bear with me. but if it helps the guys in the field, it may be worth asking.

 

[don_resqcapt19]

my calc shows a 36% fill on 3#500-2 1/2"C, which seems ok.

Unless you are using one of the new conduit bodies that have the same radius as required in Chapter 9, Table 2 for conduit bends, the wire fill is not the issue. You need a conduit body that meets the dimension requirements found in 314.28(A). In general that would require the distance between the conduit entries to that 2 1/2" C to be 20" apart. A standard C fitting is not that long.

im guessing the form7 LB is the issue. that bend looks too sharp? i have to look around more for specs and demensions but is that against code? I think i saw somewhere in the nec minimum bend radius per wire size?...

With the LB fitting, you need the conduit entries at least 15" apart if the conduit is 2 1/2". Again a standard LB fitting is not that large.
You can use a conduit body that is marked for the maximum size and number of conductors as provided for in 314.28(A)(3) or a mogul conduit body.

The issue with the marked fitting is that the code specifically says that the conduit body itself has to be marked with the maximum size and number of conductors. There is no provision that permits field calculations, or the other combination of wire sizes that is often listed in the manufacturer's information.

 

[kwired]

normally where I find them is a run with more than 360? of bends.......
3/4" EMT with 4 #12s, 4-90s and a couple of 45? offsets so the E/C slips a "C" in the run. Kinda difficult for that to raise the hair on the back of my neck whereas
(3) 500s in a 2-1/2 conduit with a Form7 LB will scare me

Your first example with the 12 AWG conductors is not in violation of anything, the second example with the 500's very well may be.