Wire fill larger then #6 in box

[scot120]

It is clear to me , for #6 and smaller to use NEC 314.16 tables.
I don't remember how to figure encloser size for larger than #6 . I was helping my son inlaw with his apprenticeship school and couldn't rember how to calculate larger conductors . Did I over look it in 314.16 or is it somewhere else in NEC ?

 

[Dennis Alwon]

Look at 314.28 it has to pipe size. IMO if it is cable then I would use the smallest connector size that is allowed but am not certain of that.

 

[qcroanoke]

Look at 314.28 it has to pipe size. IMO if it is cable then I would use the smallest connector size that is allowed but am not certain of that.

314-28 (A) 2 last paragraph: When transposing cable size into raceway size in 314-28 (A) (1) & (A) (2) the minimum metric designator (trade size) raceway required for the number and size of conductors in the cable shall be used.

 

[Dennis Alwon]

314-28 (A) 2 last paragraph: When transposing cable size into raceway size in 314-28 (A) (1) & (A) (2) the minimum metric designator (trade size) raceway required for the number and size of conductors in the cable shall be used.

Thanks, basically what I was saying but that clarifies it.

 

[scot120]

Thanks . I overlooked it last night , when I looked in 314.28 . If I'm understanding right , you first have to calculate conduit required , then calculare box size from the diameter of the conduit .
You have been a big help . I knew that back in 86' .

 

[Dennis Alwon]

Thanks . I overlooked it last night , when I looked in 314.28 . If I'm understanding right , you first have to calculate conduit required , then calculare box size from the diameter of the conduit .
You have been a big help . I knew that back in 86' .

That's correct. You knew I was a big help in '86 or you knew that code section in '86 :lol:

These images may help

 

[kwired]

Thanks, basically what I was saying but that clarifies it.

What you were saying is not really the same thing. If you can fit a particular cable in a 1-1/4 inch connector does not mean the equivalent conductors in raceway will fit in 1-1/4 inch raceway. Raceways are only filled to 40% for more than 2 conductors where just a cable connector size is not determined in that way.

 

[Dennis Alwon]

What you were saying is not really the same thing. If you can fit a particular cable in a 1-1/4 inch connector does not mean the equivalent conductors in raceway will fit in 1-1/4 inch raceway. Raceways are only filled to 40% for more than 2 conductors where just a cable connector size is not determined in that way.

I know that. My logic was the connector was sized based on the pipe size. I should have stated that.

 

[Dennis Alwon]

Besides how do you really calculate the pipe size without knowing the actually insulation used since cable does not give us this. I usually use a 1" connector for 6/3 nm and that would equate to a 1" conduit with thhn. I am not sure you could get it in a 3/4" connector.

 

[kwired]

Besides how do you really calculate the pipe size without knowing the actually insulation used since cable does not give us this. I usually use a 1" connector for 6/3 nm and that would equate to a 1" conduit with thhn. I am not sure you could get it in a 3/4" connector.

But 6 AWG is smaller than 4 AWG so box is sized on volume per conductor Even if you run it in 2 inch raceways.

 

[Dennis Alwon]

But 6 AWG is smaller than 4 AWG so box is sized on volume per conductor Even if you run it in 2 inch raceways.

You're enjoying this aren't you. Taking advantage of an old man-- shame on you. :lol:. Seriously though I would almost bet that every connector size I use for those larger cables would be right at the size of a conduit I would choose. Anyway I tend to oversize boxes anyway in case other wires get added to the mix later.

 

[scot120]

Dennis ,
I started apprenticeship class back in 1986 . I don't think I have ever used these calculations in the field . I have always had engioneered prints to go by .

Smaller then #4 Would go by tables 314.16 (A) & ( B)
#4 and larger you would have to use tables 1, 4 & 5 chapter 9
Do they have mn cable bigger than #6 ?

 

[Dennis Alwon]

Dennis ,
I started apprenticeship class back in 1986 . I don't think I have ever used these calculations in the field . I have always had engioneered prints to go by .

Smaller then #4 Would go by tables 314.16 (A) & ( B)
#4 and larger you would have to use tables 1, 4 & 5 chapter 9
Do they have mn cable bigger than #6 ?

Yep, I have used 2-3 nm with ground which is what the NEC allows-- 334.104

 

[scot120]

I haven't done much residential work . I don't see much mn .

 

[kwired]

You're enjoying this aren't you. Taking advantage of an old man-- shame on you. :lol:. Seriously though I would almost bet that every connector size I use for those larger cables would be right at the size of a conduit I would choose. Anyway I tend to oversize boxes anyway in case other wires get added to the mix later.

Majority of the time, yes the connector size will be same size as raceway would be. I seldom use any cable wiring methods larger than 6 AWG though.

 

[kwired]

Dennis ,
I started apprenticeship class back in 1986 . I don't think I have ever used these calculations in the field . I have always had engioneered prints to go by .

Smaller then #4 Would go by tables 314.16 (A) & ( B)
#4 and larger you would have to use tables 1, 4 & 5 chapter 9
Do they have mn cable bigger than #6 ?

Conductors larger than #4 and tables in chapter 9 are for sizing raceways, which you need to do anyway to determine raceway size.

You then have to go to 314.28 to size junction and pull boxes, and size is based on raceway entries.

One little saying that helps to remember the multipliers in 314.28 is "six for tricks, and eight for straight"

 

[scot120]

Kwired ,
You said ," larger than #4 " . It should be #4 and larger , per 314.28 (a)

 

[kwired]

Kwired ,
You said ," larger than #4 " . It should be #4 and larger , per 314.28 (a)

or "larger than #6"

Read what I mean and not what I write

Not the first time I have said that way but actually meant #4 and larger or larger than #6, for some reason I do that often with this particular topic. I know what it says/means but usually repeat it the wrong way.

 

[scot120]

or "larger than #6"

Read what I mean and not what I write

Not the first time I have said that way but actually meant #4 and larger or larger than #6, for some reason I do that often with this particular topic. I know what it says/means but usually repeat it the wrong way.

I'm not a good reader anyway .
I do really apreciate everyone who has posted . I was lost on the larger conductor calculations .

 

[kwired]

I'm not a good reader anyway .
I do really apreciate everyone who has posted . I was lost on the larger conductor calculations .

Have you figured them out?

Quick examples:

Pull box - straight pull 1-1/2 raceways opposite sides of box. Size of conductors does not matter other than that if they are smaller than #4 you use a volume for each conductor otherwise all that matters is we have two 1-1/2 raceways and a straight pull.

Six for tricks - eight for straight - so 1.5 x 8 = 12. We need a box that has at least 12 inches between the two opposing walls that these raceways enter. The other dimensions only need to be enough to allow the raceways to enter so this could easily be only something like 3x3x12 if such a box existed.

Now same thing but a right angle or U pull or if there are splices, we have the six for tricks multiplier. 1.5 x 6 = 9. This means that where each 1.5 inch raceway enters there needs to be a minimum of 9 inches to the opposite wall of the box.