conduit fill

[infinity]

Yes I can. My point is that your initial post:



While technically correct could lead to an incorrect answer to the question Fred posed if one did not also consider ampacity adjustments. That they do not come into play here does not mean they can be ignored. If the thread title was "Question?" instead of "conduit fill", would that help you see my point?

Take the exact same question Fred asked, make it this:

"How many #10 THHN wires allowed in 1 inch emt after derating for 30 amp circuits all separate neutrals"

Is that question answerable? and is the answer different than for 20A? yes and yes.

Fill very much has something to do with ampacity because if you put 12 #10 CCC in a 1" EMT conduit on 30A breakers you are going to fail your inspection.

My initial response was called a hint because I already knew the answer and the derating didn't alter the result from the information given. If the raceway were larger you could install more #10 THHN conductors and still be at 20 amps after derating but that's not relevant because of the maximum fill permitted by the NEC for the given 1" EMT.

 

[iwire]

I am just going to toss this out here.

Considering we do not have the exact wording of the question or the context it was presented in, trying to pick it apart seems impossible at best.

 

[ggunn]

I am just going to toss this out here.

Considering we do not have the exact wording of the question or the context it was presented in, trying to pick it apart seems impossible at best.

But it's what we do.

 

[augie47]

But it's what we do.

Yep..

Note to the original poster. Please don't let our banter deter you for continuing your questioning.

 

[infinity]

Yep..

Note to the original poster. Please don't let our banter deter you for continuing your questioning.

 

[kwired]

Ho many #10 THHN wires allowed in 1 inch emt after derating for 20 amp circuits all seprate nuetrals

Based on OP information - the only question in there is how many #10 THHN wires are allowed in a 1 inch EMT. Derating /separate neutrals only effects how many or what size of conductors are necessary to supply specific loads in a particular situation, 1 inch EMT can only handle a certain amount of #10 THHN's regardless of why #10 was chosen as the conductor size.

 

[roger]

Based on OP information - the only question in there is how many #10 THHN wires are allowed in a 1 inch EMT. Derating /separate neutrals only effects how many or what size of conductors are necessary to supply specific loads in a particular situation, 1 inch EMT can only handle a certain amount of #10 THHN's regardless of why #10 was chosen as the conductor size.

Not to mention peanut butter. :blink:

Roger

 

[kwired]

Not to mention peanut butter. :blink:

Roger

Creamy or chunky?

 

[Dennis Alwon]

Ho many #10 THHN wires allowed in 1 inch emt after derating for 20 amp circuits all seprate nuetrals

Here is what I would do... In this case either way argued above will work.

I would start at table 310.15(B)(16) and see that #10 is good for 40 amps with THHN wire. I would then proceed to Annex C Table C1 to find that 16 #10 thhn conductors can fit inside 1" emt.

Table 310.15(B)(3) states for 10-20 current carrying conductor's we must derate 50%. We have 8 circuits all with an individual neutral so they all count as current carrying conductor's (16). Since #10 is rated 40 amps at 90C then 50% is still 20 amps.

My answer is 16.

Now if we had 1 1/4" emt then there would be an issue since we would have to go to 45% which would reduce the number of conductors then what is given in Annex C

 

[kwired]

Here is what I would do... In this case either way argued above will work.

I would start at table 310.15(B)(16) and see that #10 is good for 40 amps with THHN wire. I would then proceed to Annex C Table C1 to find that 16 #10 thhn conductors can fit inside 1" emt.

Table 310.15(B)(3) states for 10-20 current carrying conductor's we must derate 50%. We have 8 circuits all with an individual neutral so they all count as current carrying conductor's (16). Since #10 is rated 40 amps at 90C then 50% is still 20 amps.

My answer is 16.

Now if we had 1 1/4" emt then there would be an issue since we would have to go to 45% which would reduce the number of conductors then what is given in Annex C

The question asks how many #10 wires can fit in the raceway, not how many 20 amp circuits can go in the raceway. If it asked how many 20 amp circuits, there is lack of details that are necessary to answer that, so how we come up with needing to use #10 conductors is not part of the question - just how many will fit in the raceway. If anything the missing details here may be whether we need to fill to 40% or 60%.

 

[dkidd]

Creamy or chunky?

What color is the bathroom. And here they go again.

Has anyone read http://forums.mikeholt.com/showthread.php?t=181733? :weeping:

 

[Dennis Alwon]

The question asks how many #10 wires can fit in the raceway, not how many 20 amp circuits can go in the raceway. If it asked how many 20 amp circuits, there is lack of details that are necessary to answer that, so how we come up with needing to use #10 conductors is not part of the question - just how many will fit in the raceway. If anything the missing details here may be whether we need to fill to 40% or 60%.

I did not answer that there are 8 circuits but rather there are 16 conductors allowed in the conduit in order to have a 20 amp circuit. Why was 10 awg given? Why was 20 amp circuit given?

Why would we fill to 60%-- that is for a nipple 24" or less. That was not given so IMO one would answer this at 40% . I have seen hundreds of conduit fill questions that do not specify the length. IMO, if they were looking for 60% they would have said a 24" run of emt.

 

[kwired]

The guy that retaliates is usually the one that gets penalized.

 

[kwired]

I did not answer that there are 8 circuits but rather there are 16 conductors allowed in the conduit in order to have a 20 amp circuit. Why was 10 awg given? Why was 20 amp circuit given?

Why would we fill to 60%-- that is for a nipple 24" or less. That was not given so IMO one would answer this at 40% . I have seen hundreds of conduit fill questions that do not specify the length. IMO, if they were looking for 60% they would have said a 24" run of emt.

I didn't do any of the fill calculations - but I am starting to see where there may be a little trick to this question if not read very carefully.

I think a better question that still requires using same skills to answer would be to specify a number of specific loads and ask to find what size conductors and what size raceway would be required to supply those loads, more of a real world question, but that is just my thoughts.

 

[iwire]

I think a better question that still requires using same skills to answer would be to specify a number of specific loads and ask to find what size conductors and what size raceway would be required to supply those loads, more of a real world question, but that is just my thoughts.

Answer the OPs question or start a new thread about your thoughts

 

[kwired]

Answer the OPs question or start a new thread about your thoughts

Delete my last paragraph in my last post then, I have no problem with it.

 

[JFletcher]

Now that the question has been answered, a follow up to my caveat of using on-line fill tables:

http://www.cesjoplin.com/DATA/conduitfill.pdf

Shows 18 #10s in a 1" conduit

So does this:

http://www.alanwire.com/tech/conduit.html

'based on 1993 NEC'

 

[Dennis Alwon]

Those tables don't break down as to what type of conduit. If you use tables 4 and 5 in the NEC it also comes out 16 conductors. Perhaps the thhn back then was smaller???

 

[kwired]

They didn't add separate tables for each raceway type until either 1996 or 1999 IIRC. Not all raceways of same trade size have same fill capacity.

 

[Carultch]

The question asks how many #10 wires can fit in the raceway, not how many 20 amp circuits can go in the raceway. If it asked how many 20 amp circuits, there is lack of details that are necessary to answer that, so how we come up with needing to use #10 conductors is not part of the question - just how many will fit in the raceway. If anything the missing details here may be whether we need to fill to 40% or 60%.

The mention of derates seems to be a red herring. It gives you the size, and the question is only focusing on the mechanical fit of those conductors in a raceway.