3" Condulet Over Fill?

Status
Not open for further replies.
314.28 states: "marked with the maximum numbet and maximum size conductors permitted".3# conductors refers to 40% per table 1 chapter 9. The conductor size gives the allowable area in sq.in.
 
hyetal said:
314.28 states: "marked with the maximum numbet and maximum size conductors permitted".3# conductors refers to 40% per table 1 chapter 9. The conductor size gives the allowable area in sq.in.
Click to expand...

I see nothing in 314.28(A)(3) that would allow you to use a calculation to install something other than what's marked on the inside of the conduit body.

314.28(A)(3) Smaller Dimensions. Boxes or conduit bodies of di-
mensions less than those required in 314.28(A)(1) and
(A)(2) shall be permitted for installations of combinations
of conductors that are less than the maximum conduit or
tubing fill (of conduits or tubing being used) permitted by
Table 1 of Chapter 9, provided the box or conduit body has
been listed for, and is permanently marked with, the maxi-
mum number and maximum size of conductors permitted
Click to expand...
 
hardworkingstiff said:
I agree, and I also don't understand how they get by not having to comply with 314.28.

I would hate to pull some larger conductors through a C (pull them out then back in) with the short distance in that body. I don't think you could ever get the conductor to straighten out, and I bet the insulation gets nicked.

But, 8 times is also a bit more than I would need.
Click to expand...

who is to say C's are for strictly a pulling point or to satisfy the 360 degree rule, what if it was just used to add more pulling compound (soap) and not a pull point? If you need a pulling point and are worried about that, get a mogal C. which basically is a C on steroids


This is a pic of a 1/2" mogul LB
http://www.grainger.com/genericZoom...uit Body, Style LB, 1/2 In, Iron&ref_page=idp
 
Last edited:
infinity said:
I see nothing in 314.28(A)(3) that would allow you to use a calculation to install something other than what's marked on the inside of the conduit body.
Click to expand...

so your stating that I can not put 4 number 12 thhn wires in a 4" LB?
 
hyetal said:
Don for RMC it's 344.22 . It's .22 in most raceway articles. EMT 358.22 etc.
Click to expand...
That is for raceway fill and has nothing to do with the use of pull boxes or conduit bodies.

The point is that when you are are installing conductors #4 and larger, in many cases, you are not permitted to use a standard conduit body of the same trade size as the raceway.
 
infinity said:
Like it or not according to the NEC that would be a violation. As Don and others have said the NEC is pretty clear on this, comply with the 6X and 8X rules or what's stamped within the conduit body otherwise use a larger CB or a pull box.
Click to expand...

don_resqcapt19 said:
Show me the code section that says you can install the five #4s in a conduit body marked for three 4/0s.
Click to expand...

Since the 2 of you are saying this, I'd wager it's not in the NEC.

Just out of curiosity, how is it that these LBs that do not meet the 6x rule have been allowed to be stamped and used?
 
infinity said:
I see nothing in 314.28(A)(3) that would allow you to use a calculation to install something other than what's marked on the inside of the conduit body.
Click to expand...

No, but I believe you would be allowed (without argument) to install smaller conductors of the same number stamped in the body. In the example of installing 5# 4's, 3#4's are allowed because the conduit body says max and that would not be exceeded.

I also believe more realistic people with common sense have realized that if you significantly reduce the size of the conductors that you should be allowed to increase the number of conductors so long as the square inch area of smaller conductors does not exceed the square inch area of the maximum conductors allowed by the markings in the conduit body.

I'm glad those people are in charge, and I wish the code would address this and put something in writing about it.
 
I have to say in my experience 314.28 when it comes to conduit bodies ranks in the top 10 "least enforced NEC rules" in this area and I am as guilty as many of my fellow inspectors. With some of the conductor damage I have seen I don't know why it is not more rigidly enforced other than the fact that it is so often overlooked gives rise to major emotions when it is enforced.
The Code's failure to address "other combinations of conductors" or add wording along the line of that in the Carlon letter noted in earlier post #11 compounds to the enforcement problem.
 
augie47 said:
I have to say in my experience 314.28 when it comes to conduit bodies ranks in the top 10 "least enforced NEC rules" in this area and I am as guilty as many of my fellow inspectors. With some of the conductor damage I have seen I don't know why it is not more rigidly enforced other than the fact that it is so often overlooked gives rise to major emotions when it is enforced.
The Code's failure to address "other combinations of conductors" or add wording along the line of that in the Carlon letter noted in earlier post #11 compounds to the enforcement problem.
Click to expand...

Augie, in the earlier example, would you allow the 5 #4's to be installed in the LB that is rated for 3 #4/0 conductors?
 
Yes. But, in doing so I think I would be allowing a violation. I lean more to following the guidelines in the Carol letter.

Out of curiosity I started another thread (poll) to see how often this is enforced as written.
 
The Max no and size of conductors marked 3-3/0.that means 3 conductors per table 1 chapter 9 is 40% fill. 4/0 area is .219?3= .657 sq in. 5 #4 .042?5= .21sq in 1/3 the area.the three plus the size conductor is the maximum at 40%. 314.28(A)(3)allows combinations of conductors that are less than the Max.see art.314.28(A) (3).
 
hyetal said:
The Max no and size of conductors marked 3-3/0.that means 3 conductors per table 1 chapter 9 is 40% fill. 4/0 area is .219?3= .657 sq in. 5 #4 .042?5= .21sq in 1/3 the area.the three plus the size conductor is the maximum at 40%. 314.28(A)(3)allows combinations of conductors that are less than the Max.see art.314.28(A) (3).
Click to expand...

See Post #24
 
hyetal said:
The Max no and size of conductors marked 3-3/0.that means 3 conductors per table 1 chapter 9 is 40% fill. 4/0 area is .219?3= .657 sq in. 5 #4 .042?5= .21sq in 1/3 the area.the three plus the size conductor is the maximum at 40%. 314.28(A)(3)allows combinations of conductors that are less than the Max.see art.314.28(A) (3).
Click to expand...
The marking of the maximum number and size of conductors on a conduit body has nothing to do with the raceway fill rules. The marking on a standard conduit body will be much less than the permitted wire fill for a raceway of the same trade size as the conduit body.
 
hardworkingstiff said:
No, but I believe you would be allowed (without argument) to install smaller conductors of the same number stamped in the body. In the example of installing 5# 4's, 3#4's are allowed because the conduit body says max and that would not be exceeded.

I also believe more realistic people with common sense have realized that if you significantly reduce the size of the conductors that you should be allowed to increase the number of conductors so long as the square inch area of smaller conductors does not exceed the square inch area of the maximum conductors allowed by the markings in the conduit body.
Click to expand...

If the conductors are larger than #6 the NEC provides no basis to do what you propose. Common sense may say otherwise and I agree that if a conduit body says max 3-#3/0's then one can easily install 5-#4's but no one in this thread had provided any code wording stating that it would be permitted to install more conductors than what is stamped in the conduit body even if they're of smaller size.

Bottom line is the NEC wants you to use a CB with either the 6X or 8X rule calculation, the manufacturer can provide some leeway if you follow what they have stamped within the conduit body. If they stamped nothing in the conduit body then what?
 
314.28(A)(3) Smaller Dimensions.Boxes or conduit bodies of dimensions less than those required in (A)(1)and(A)(2) shall be permitted for installations of combinations of conductors etc.The operative word being SHALL
 
Interesting statement from IAEI.

The marking requirement indicating the maximum size conductor for which the ?smaller dimension? conduit body has been found acceptable is straightforward. And, the maximum number of the same size maximum conductor can also be clearly indicated in the marking. Particularly in larger size conduit bodies, however, often more than one size conductor is pulled into a conduit body and it is not always clear by the manufacturer?s markings what combinations of conductors are included in the conduit body listing. The only sure way to make this determination is to utilize the same method as one would to calculate the conductor fill in a conduit where various size conductors will be installed (see NEC chapter 9 tables). Since the conduit body manufacturer clearly provides the marking of the maximum size conductor and the maximum number of that conductor, one is able to calculate the percentage wire fill represented for the smallest conduit body hub size in a through run. Any additional combinations of conductor sizes must comply with that calculated conduit wire fill percentage for that size conduit.
Click to expand...



http://www.iaei.org/magazine/2006/01/conduit-bodies-and-their-use-in-accordance-with-the-nec/
 
Status
Not open for further replies.
Top