You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Junction Box Full
- Thread starter elcam
- Start date
- Status
- Not open for further replies.
Re: Junction Box Full
Assuming you mean 3R enclosure (raintight), All conductors being larger than #4 AWG, 314.28(A)(2) tells us for angle pulls (again assumed), we need 6 times the trade size, plus the sum of the diameters of all other entries in the same row on the same wall of the box. Again assuming your four three-inch and one two inch are all in a row, (6 x 3) + (3 x 3) + 2 = 29 inches minimum tall. I would use a 30 x 30 x 6 box. Remember that the conduit holes into the building must be in the top of the back section of the box. How do you intend to maintain the rainproofness of the box? Raintight hubs? Five "mogul" LB conduit bodies might be a better option.
Assuming you mean 3R enclosure (raintight), All conductors being larger than #4 AWG, 314.28(A)(2) tells us for angle pulls (again assumed), we need 6 times the trade size, plus the sum of the diameters of all other entries in the same row on the same wall of the box. Again assuming your four three-inch and one two inch are all in a row, (6 x 3) + (3 x 3) + 2 = 29 inches minimum tall. I would use a 30 x 30 x 6 box. Remember that the conduit holes into the building must be in the top of the back section of the box. How do you intend to maintain the rainproofness of the box? Raintight hubs? Five "mogul" LB conduit bodies might be a better option.
G
Guest
Guest
Re: Junction Box Full
early dean. The formula you gave was correct as to the math involved but you must be very carefull not to use the result to size the box without applting the rest of the paragraph in (A)(2). which says "The distance between raceways entries enclosing the same conductor shall not be lees than 6 times the trade size of the larher raceway". Note that it says between raceways. You need a box which will allow for that dimension which in this case might be 36x36. If you have acess to a CXharles R miller illustrated guide to the NEC look on page 43 of the 2002 book note c and especially his diagram below thata has dimension c shown. You have to have a box sized per that dimension. Hope I havent confused anyone but had a big time argument with a job super about this exact issue on an angle pull wher he made me use a 24x24 box on 4 inch rigid. 6x4 is 24 right. problem was you could not get this dimension when the inlet pipe came in the bottom of the box and the out let was about 4 inches down from the top back of the box resulting in about 18 inches. He insisted he was right. I installed because I had no choice. The inspector took one look and said sorry. Change It ! Ruined 2 24 inch boxes and also of course had to pull the 3 500 mcm cables back about 45 feet to change this out not to metion the time involved. 36x36 boxws sokved the problem but the time and effort involved was considerable. Anyhow be carefull you have enough room as most inspetors on commercial work will catch this in a heartbeat.
early dean. The formula you gave was correct as to the math involved but you must be very carefull not to use the result to size the box without applting the rest of the paragraph in (A)(2). which says "The distance between raceways entries enclosing the same conductor shall not be lees than 6 times the trade size of the larher raceway". Note that it says between raceways. You need a box which will allow for that dimension which in this case might be 36x36. If you have acess to a CXharles R miller illustrated guide to the NEC look on page 43 of the 2002 book note c and especially his diagram below thata has dimension c shown. You have to have a box sized per that dimension. Hope I havent confused anyone but had a big time argument with a job super about this exact issue on an angle pull wher he made me use a 24x24 box on 4 inch rigid. 6x4 is 24 right. problem was you could not get this dimension when the inlet pipe came in the bottom of the box and the out let was about 4 inches down from the top back of the box resulting in about 18 inches. He insisted he was right. I installed because I had no choice. The inspector took one look and said sorry. Change It ! Ruined 2 24 inch boxes and also of course had to pull the 3 500 mcm cables back about 45 feet to change this out not to metion the time involved. 36x36 boxws sokved the problem but the time and effort involved was considerable. Anyhow be carefull you have enough room as most inspetors on commercial work will catch this in a heartbeat.
- Status
- Not open for further replies.