# Thread: Sizing wireway

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## Sizing wireway

So I have 8 #250 in (2) 2 1/2” I need a wireway plus I need to splice In the wireway I’m also going from 250 aluminum to 3/0 copper just trying to understand this better

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I'd go with 6x6x3

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Originally Posted by vortiz.08
So I have 8 #250 in (2) 2 1/2” I need a wireway plus I need to splice In the wireway I’m also going from 250 aluminum to 3/0 copper just trying to understand this better
You would use art. 376.23 and 314.28 to size it. Wires larger than #4 require the 6 or 8 multiplier based on conduit size. You multiply your largest conduit size by 6 or 8 depending straight or angled pulls, then add all of your other conduits (2.5x8=20+2.5 =22.5). So one of the dimensions of your wireway would have to be greater than or equal to 22.5"

4. There is no need to add the extra conduit sizes on a straight pull. It's simply 8X the largest conduit size.

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But I will have splices in this how do I calculate that

6. Originally Posted by vortiz.08
But I will have splices in this how do I calculate that
Splices only require 6X in the code rules, but in my opinion for what you are doing even 8X is not enough. What method are you using to make the splices?

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Originally Posted by vortiz.08
But I will have splices in this how do I calculate that
May be wrong here but you don't need to calculate for splices. Using the multiplier (6 or 8) times the largest conduit will take this into account. Box fill is only used with conductors smaller that #4

8. Originally Posted by MattS87
May be wrong here but you don't need to calculate for splices. Using the multiplier (6 or 8) times the largest conduit will take this into account. Box fill is only used with conductors smaller that #4
376.22(A) says 20 percent fill for the contained conductors

376.56(A) says the conductors and splices can't fill any cross section more then 75 percent. So the splicing method will make some difference - though staggering splices so they are not all at same cross section will help with that.

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Originally Posted by kwired
376.22(A) says 20 percent fill for the contained conductors

376.56(A) says the conductors and splices can't fill any cross section more then 75 percent. So the splicing method will make some difference - though staggering splices so they are not all at same cross section will help with that.
Good to know. So per the OP's question, how would you calculate how much fill the splices take up? Based on splice method?

10. Originally Posted by MattS87
Good to know. So per the OP's question, how would you calculate how much fill the splices take up? Based on splice method?
Absolutely based on splice method. Crimped butt splice type devices typically won't take up as much room as Polaris connectors or similar.

conductor fill probably isn't too much issue, especially if entering with raceways at the "ends", as the wireway has to be larger then the raceway(s) just to terminate into the wireway. If running 2 -2.5 inch raceways into an end - you probably need at least 8 inch by 4 inch wireway - presuming that is something available 8x8 is probably something more common though and would have quite a bit of room for splicing - still may want to stagger splices to some extent especially with terminal blocks or polaris connectors.

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