Conduit bodies

[PWRUP]

Can conduit bodies be used as a pulling point??
If so, what part of the code would support this??

 

[Carultch]

Can conduit bodies be used as a pulling point??
If so, what part of the code would support this??

That is precisely why they are manufactured. Especially the type-C conduit body (straight pull), which would have few (if any) other purposes.

 

[infinity]

Can conduit bodies be used as a pulling point??
If so, what part of the code would support this??

Yes and no. For conductors #6 and smaller yes. For #4 and larger only if the conduit body is sized at 6X for angles (type LB and others) or 8X (type C) for straight pull. Standard conduit bodies do not meet the 6X and 8X rules. I've seen many 4" EMT runs with C conduit bodies that do not count as a pull point.

 

[PWRUP]

Do you have the section of the code that supports this??
To be more specific, if installing 4 , 3/0 THHN conductors in a 2" EMT, and you install a 'C' condulet it doesn't meet the requirement of 8 times the trade size of the conduit size for a straight pull. See were I'm going?

 

[infinity]

Do you have the section of the code that supports this??
To be more specific, if installing 4 , 3/0 THHN conductors in a 2" EMT, and you install a 'C' condulet it doesn't meet the requirement of 8 times the trade size of the conduit size for a straight pull. See were I'm going?

That's correct. Look at 314.28. You size conduit bodies just like you would size a pull box.

 

[augie47]

That's correct. Look at 314.28. You size conduit bodies just like you would size a pull box.

If I may, you SHOULD size conduit bodies just like you would size a pull box

as you noted, many are not.

 

[JFletcher]

The larger ones can be used as a pull point but do not count as a pull point... iow, if you have a length of large conduit with 6 90* bends in it, and a condulet body right in the middle, you still have a run of conduit with more than 360* between pull points by the 3xx.26 sections of code.

eta: should have read the other posts first. What Rob wrote.

 

[infinity]

The larger ones can be used as a pull point but do not count as a pull point... iow, if you have a length of large conduit with 6 90* bends in it, and a condulet body right in the middle, you still have a run of conduit with more than 360* between pull points by the 3xx.26 sections of code.

eta: should have read the other posts first. What Rob wrote.

I agree and I see this often with six, seven or eight 90's and a C in the middle. At least it helps to get the rope in.

 

[Carultch]

Yes and no. For conductors #6 and smaller yes. For #4 and larger only if the conduit body is sized at 6X for angles (type LB and others) or 8X (type C) for straight pull. Standard conduit bodies do not meet the 6X and 8X rules. I've seen many 4" EMT runs with C conduit bodies that do not count as a pull point.

By that logic, you would expect that conduit bodies size 2" and larger, would come built to the 6X and 8X rules by design. Note that NEC2017 now allows you to size conduit bodies from their datasheet capacity of wires, and use any mix of smaller wires equivalent to that in cross sectional area.

Would conduit bodies count as pull points, if they were oversized with reducing bushings, such that they meet the 6X & 8X rules based on the reduced entry sizes?

I know when you do that, you run in to the issue of them needing support other than the raceway being supported within 3 ft of all entries. How you would do that, I do not understand, as conduit bodies don't come with mounting screw holes.

 

[kwired]

The conduit body can also be marked with maximum number and size of conductors and not need to be 6 -8 times trade size of raceway in length.

It is hard to put every possible combination of conductors that might be pulled on it though - especially on say a 4 inch trade size.

 

[infinity]

By that logic, you would expect that conduit bodies size 2" and larger, would come built to the 6X and 8X rules by design. Note that NEC2017 now allows you to size conduit bodies from their datasheet capacity of wires, and use any mix of smaller wires equivalent to that in cross sectional area.

Would conduit bodies count as pull points, if they were oversized with reducing bushings, such that they meet the 6X & 8X rules based on the reduced entry sizes?

I know when you do that, you run in to the issue of them needing support other than the raceway being supported within 3 ft of all entries. How you would do that, I do not understand, as conduit bodies don't come with mounting screw holes.

You could certainly use an oversized conduit body to the you the required 6X or 8X length. You're correct the 2017 NEC has provided some relief in the requirement as well as what kwired posted for earlier code versions.

 

[Carultch]

The conduit body can also be marked with maximum number and size of conductors and not need to be 6 -8 times trade size of raceway in length.

It is hard to put every possible combination of conductors that might be pulled on it though - especially on say a 4 inch trade size.

314.28(A)(3) has an update in 2017, that allows any combination of smaller conductors than those identified in the conduit body, as long as the total cross sectional area does not exceed the same cross sectional area as that for which the conduit body is rated.


Example: if the body is rated for 3x 500 kcmil, in XHHW-2 wire, that is 2.038 in^2. Another combination that could fit, would be 6x #4/0, and 1x #3, which is 1.967 in^2.

 

[don_resqcapt19]

... Note that NEC2017 now allows you to size conduit bodies from their datasheet capacity of wires, and use any mix of smaller wires equivalent to that in cross sectional area.
...

It actually doesn't permit the use of the manufacturer's data sheet, but it does permit a volume calculation based on the size and number of conductors that is stamped on the conduit body. I had a proposal that was rejected that would have specifically permitted the use of the data sheet, but it was rejected by the CMP. The volume calculation permitted by the code should match up with the data sheet, but I have never checked.

 

[Carultch]

It actually doesn't permit the use of the manufacturer's data sheet, but it does permit a volume calculation based on the size and number of conductors that is stamped on the conduit body. I had a proposal that was rejected that would have specifically permitted the use of the data sheet, but it was rejected by the CMP. The volume calculation permitted by the code should match up with the data sheet, but I have never checked.

I would expect that if it is stamped on the conduit body, it would be the same as that which is written on the datasheet. No?

 

[don_resqcapt19]

I would expect that if it is stamped on the conduit body, it would be the same as that which is written on the datasheet. No?

I have not done the calculations to see if the other combinations on the data sheet match the volume calculation that is permitted in the code. It should, but there have been errors in the Annex C conduit fill numbers in the past.