Code Quiz

Sep 23, 2004 11:01 AM, By Steven Owen

Imagine a metal junction box that is 32 inches x 32 inches x 6 inches with two 4-inch EMT raceways connected directly across from one another on opposite walls. Each 4-inch raceway contains three 250 kcmil conductors. An additional 2-inch EMT raceway, which contains three 4/0 AWG XHHW conductors, is connected to the back wall of the junction box directly opposite the removable cover, and another 2-inch EMT raceway has been connected to the bottom of the enclosure for a tap to a piece of industrial equipment. The 4/0 AWG conductors, which pass through the junction box, are installed in the 2-inch raceways. What's the minimum dimension required between either of the 4-inch raceways (installed in a horizontal position) and the 2-inch raceway connected to the bottom of the enclosure (installed in a vertical position)? Note: No conductors are installed between either of the 4-inch raceways or either of the 2-inch raceways.

A) 32 inches
B) 24 inches
C) 4 inches
D) No requirement for this installation

Answer: D)

Explanation: The following sentence located directly beneath the Exception to 314.28(A)(2) is seldom read, but its content is still important: “The distance between raceways enclosing the same conductor shall not be less than 6 times the trade diameter of the larger raceway.” This applies to angle or U-pulls, and it could be applied to 2-inch raceways, but not those in the question posed. In this example there’s no angle pull between the 4-inch raceway(s) and the 2-inch raceway(s), so this requirement doesn’t apply as the question is written.

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states.