Hello everybody. I left my NEC at home and need to size a pull box ASAP. I will have 12(twelve) 3 1/2 inch emt's in and 12 out. Each will have 4 500mcm and 1 1/0. All conductors will make a 90 degree turn in this box. Thanks in advance, Richard
Adding to what Yooper said, make sure that the raceways containing the same conductors ie; Raceway "A" has conductors coming into the pull box and Raceway "B" has these conductors going out are at least 21 inches apart.
the six comes from 314.28 (2) Angle ,U pills, Or splices. The distance between raceways enclosing the conductors shall not be less then SIX TIMES the metric designator (Trade size) of the larger raceway. I don't recall a Question about the ampacity ??? This could be 12 - 400 amp feeders for all we know.
First of all I want to say thanks for everyones input. What I am doing is refeeding a 475' piece of 3000amp busduct. The Ideal way would be to extend the duct, however it was installed in 1951 and I have not been able to find matching duct. I wouldn't really call this a high rise. It's 5 stories, 1.5 million square feet. Complete rehab. All switch gear and bus duct is original. We have redone the risers and panels on parts of 3 floors. The building had it's own generators when built. We removed those and tied it into POCO's grid last year. If anyone knows where to get about 100 feet of 50 year old Westinghouse 3000amp bus duct, then I won't need that pull box.
Sparky, One way of solving your problem is to install any type of new 3000 amp busway from the source to a point close to the terminal cabinet of the old busway. Install a terminal cabinet on the new busway and a set of short conduit nipples to the old busway terminal cabinet. Install 500kcmil (or smaller parallel) jumpers from new to old. You will be tens of thousands of dollars ahead of the game. Materials may be more expensive, labor will be way less!!! Homer