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Old 02-28-2009, 11:40 PM   #1
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Default Pull box size

concerning pull boxes. is there a rule of thumb to extend the size of a pull box beyond the minimum requirement?
This is in Chicago.

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Old 02-28-2009, 11:49 PM   #2
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concerning pull boxes. is there a rule of thumb to extend the size of a pull box beyond the minimum requirement?
This is in Chicago.
it all depends on the conductor size and raceway size. anything 4 and above needs a calculation

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Old 02-28-2009, 11:53 PM   #3
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i dont have a code book handy so this is all off the top of my head. for a straight pull its 8 times the size of the largest raceway plus the sum of all the others in the same row. for angle pulls its 6 times the largest raceway size plus the sum of all the others in the same row and U pulls is 6 times the largest raceway

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Old 03-01-2009, 12:14 AM   #4
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thank you. i should have been more specific. for the angle pull, the distance between the conduits enclosing the the same conductors also must be 6 times the dia. of the largest conduit. a 36" sq. box will not be big enough for (4) 4" emts coming in from two sides when you take into account the fittings and locknuts.
so should 1" or more always be added to the size of the box as a general rule or is this something that is usually worked in the field. i'll look for answer tomorrow.

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Old 03-01-2009, 08:00 AM   #5
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BIGGER is always better with pull boxes. Do not be ridiculous but oversizing is in 99% of the cases well worth the added expense.
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Old 03-01-2009, 08:49 AM   #6
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thank you
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Old 03-01-2009, 08:55 AM   #7
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The calculations will often yield a box size that doesn't even exist. I would tend to go the larger box size that is in stock someplace. If you're doing something special inside it, like racking conductors on insulator racks or making taps, then the depth you'll need should be taken into account as well. From a marketing standpoint, the bigger junction boxes are a way to add value to the job (sizzle) for very little expense. "Wow, they must be doing some good work. Look at the size of those junction boxes".
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Old 03-01-2009, 09:05 AM   #8
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BIGGER is always better with pull boxes. Do not be ridiculous but oversizing is in 99% of the cases well worth the added expense.
what he said.
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Old 03-01-2009, 09:12 AM   #9
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I've come to believe that some guys have made it their personal mission in life to use the smallest legal pull box (and device box, for that matter), for everything they do. I don't think they realize that they've caused themselves 100 dollars worth of aggravation to save 50 dollars. Not to mention, if you scuff a pull trying to work with too small of a junction box, you're screwed. I'm all for saving money, but a for the cost of the next larger pull box, I'm willing to spend the couple extra bucks.
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Old 03-01-2009, 11:11 AM   #10
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the fomula i gave you is straight out of the NEC. the NEC is minimum standards. like brian and marc said bigger is always better. the 36 inch box is minimum. if your pulling in 500s or 600s then a box thats bigger is always needed to make life easier
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Old 03-01-2009, 11:15 AM   #11
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Oh, by the way... if any of you guys are the one's who jam a chunk of 2x4 into overhead junction boxes to hold the conductors in so you can get the cover on, I hate you. It's been twice lately that I've been clobbered by lumber falling out of a junction box as I take the cover off.
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Old 03-01-2009, 11:28 AM   #12
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Oh, by the way... if any of you guys are the one's who jam a chunk of 2x4 into overhead junction boxes to hold the conductors in so you can get the cover on, I hate you. It's been twice lately that I've been clobbered by lumber falling out of a junction box as I take the cover off.
Not to laugh at you BUT I have Taken the skin off my nose more than once.
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Old 03-01-2009, 12:14 PM   #13
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BIGGER is always better with pull boxes. Do not be ridiculous but oversizing is in 99% of the cases well worth the added expense.

I agree with this 100%.
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Old 03-01-2009, 12:28 PM   #14
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Oh, by the way... if any of you guys are the one's who jam a chunk of 2x4 into overhead junction boxes to hold the conductors in so you can get the cover on, I hate you. It's been twice lately that I've been clobbered by lumber falling out of a junction box as I take the cover off.
that was SOP for many years.

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