J-box calu

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don_resqcapt19 said:
Here is what the change for the 2008 code did. If you have a straight pull, the minimum length of the box is 8 times the conduit size. If you have the same installation, but you are splicing in the pull box the 8 times conduit size is permitted to be reduced to 6 times.
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Thanks, Don. I had missed that. Read right over it

raider1 said:
I would like to know this as well.

Chris
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as would I
 
as for the depth of the box, would you put a 4" conduit in a box with a four inch depth? you could, but you also have to consider the locknut, though you could cut one of the ridges off the locknut but why. The x2 is for sizing the depth. its best to to have extra size as a just-in-case. just in case you forgot a conduit. you do not HAVE to the x2, but in case you forgot something its better to have that little extra space.
 
It sounds like the x2 is "sparkeyboy's code" :smile:. I would think the exception listed in 314.28(A)(2) might be more applicable in determining depth.
 
augie47 said:
It sounds like the x2 is "sparkeyboy's code" :smile:. I would think the exception listed in 314.28(A)(2) might be more applicable in determining depth.
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So wires per terminal: most schools that i have done have had 2 sets of 4 wires per terminal, so 12". i have used 6". not including ground.
 
sparkyboys said:
as for the depth of the box, would you put a 4" conduit in a box with a four inch depth? you could, but you also have to consider the locknut, though you could cut one of the ridges off the locknut but why. The x2 is for sizing the depth. its best to to have extra size as a just-in-case. just in case you forgot a conduit. you do not HAVE to the x2, but in case you forgot something its better to have that little extra space.
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So the X2 is your rule of thumb. That is fine, but there is no NEC requirement for X2 for the depth of the box. As Augie pointed out if one of the conduits enter oppsite the removable cover the depth of the box would be sized in accordance with Table 312.6(A).

Chris
 
same rule should apply to instructors as we say it does to inspectors.
ask him for a Code reference :smile:
 
Sparkyboys,

you aren't the problem, your instructor is--if he or she is teaching per his or her preference!

You'll find yourself correcting others if you do your homework.
 
sparkyboys said:
NOT my rule of thumb. the instructor for continuing education said x2, not me.
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That's why we're all asking about it. When someone reads a post and sees your calculation with the depth needs to be 2X the pipe size they might take that as a code requirement which is is not. The depth only need be as deep as needed to install the locknut(s) and bushing. Thanks for the clarification.
 
infinity said:
That's why we're all asking about it. When someone reads a post and sees your calculation with the depth needs to be 2X the pipe size they might take that as a code requirement which is is not. The depth only need be as deep as needed to install the locknut(s) and bushing. Thanks for the clarification.
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True, i am not taking offense, that is i posted of where i had learned this. I mean, it may not be a code requirement but it is a good rule of thumb. Thanks for of your input on this situation.:smile:
 
So, please tell me if I'm correct...

Let's say I have a junction box with a 2" conduit entering the top, a 2" entering the bottom and I am making splices.

Length = 2" x 6 = 12".
Width = 2" + 2" = 4"
Depth = 2 x 2" = 4" (per sparkyboys' rule of thumb) or at least enough for luck nut (per NEC).

Assuming that wire is at least #4 in size, then wire size/count do not come into play, right?
 
Jbox sizing with a splice?

Jbox sizing with a splice?

Expanding this topic somewhat further, how do you determine the amount of additional space in the Junction box to install a power distribution block, such as a Square D #9080LBA365212 (dimensions:8.54"x5.5"x3.12")?
 
don_resqcapt19 said:
Here is what the change for the 2008 code did. If you have a straight pull, the minimum length of the box is 8 times the conduit size. If you have the same installation, but you are splicing in the pull box the 8 times conduit size is permitted to be reduced to 6 times.
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I'm not seeing this in Art. 314 of the 2008 NEC. All changes for 2008 are shaded in gray. Could you point this out for me? TIA
 
elohr46 said:
I'm not seeing this in Art. 314 of the 2008 NEC. All changes for 2008 are shaded in gray. Could you point this out for me? TIA
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The heading of 314.28(A)(2) was changed to add "or splices". This basically means that even if the conduits are arranged in a straight pull configuration, if you install splices in the conductors you must use the same sizing method as an angle or U-pull.

Chris
 
raider1 said:
The heading of 314.28(A)(2) was changed to add "or splices". This basically means that even if the conduits are arranged in a straight pull configuration, if you install splices in the conductors you must use the same sizing method as an angle or U-pull.

Chris
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Yes, I saw that for angle or U pulls, but the poster I was referring to quoted straight pulls. There's nothing changed for straight pulls from what I can see.
 
elohr46 said:
Yes, I saw that for angle or U pulls, but the poster I was referring to quoted straight pulls. There's nothing changed for straight pulls from what I can see.
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If you read Don's post he is mentioning that if the same straight pull is now spliced in the j-box it would need to comply with 314.28(A)(2) for Angle or U-pulls or splices.

Chris
 
elohr46 said:
Yes, I saw that for angle or U pulls, but the poster I was referring to quoted straight pulls. There's nothing changed for straight pulls from what I can see.
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If you splice the conductors in the pull box, it is not a "straight pull" and the code change for 2008 will permit the use of a smaller box when the conductors are spliced in a box where the conduits enter one side of the box and exit the opposite side of the box. If you pull through without a splice the distance between the sides of the box must be 8 times the conduit size, but if you splice the distance only needs to be 6 times the conduit size.
 
don_resqcapt19 said:
If you splice the conductors in the pull box, it is not a "straight pull" and the code change for 2008 will permit the use of a smaller box when the conductors are spliced in a box where the conduits enter one side of the box and exit the opposite side of the box. If you pull through without a splice the distance between the sides of the box must be 8 times the conduit size, but if you splice the distance only needs to be 6 times the conduit size.
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Thanx, I now understand what you were saying in the beginning.
 
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