You are designing a horizontal distribution system that will have a zone box located 71.6 m (235 ft) away from the telecommunications room (TR). A 50 mm (2 in) conduit is designed from the TR to a pull box located 36.6 m (120 ft) away from the TR. A 1 1/2 inch conduit is designed from the pull box to the zone box located 35.1 m (115 ft) beyond the pull box. Assuming no conduit bends, and excluding the TR and zone box, what is the total number of pull boxes/pull points required in this horizontal conduit system between the telecommunications room (TR) and zone box?

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Quizplus · Accepted Answer

According to NEC 2017 Article 300.19(A), "where the length of the conduit or tubing from the last point of support to the outlet or termination point exceeds 1000 mm (3 ft), as used in this section, a box or conduit body shall be installed at least every 1000 mm (3 ft) thereafter". 
In this case, the distance between TR and the pull box is 36.6 m (120 ft) which is equal to 36 boxes, and the distance between the pull box and the zone box is 35.1 m (115 ft) which is equal to 34 boxes. Therefore, a total of 70 boxes are required. According to NEC 2017 Article 328.24(B)(1), "conduits that are 2 in. or smaller, and are run exposed for a total length of not more than 3.05 m (10 ft) can be wired without the installation of conduit bodies or pull boxes". Therefore, only one pull box is required in the 50 mm (2 in) conduit between TR and pull box. Hence the total number of pull boxes/pull points required in this horizontal conduit system between the telecommunications room (TR) and zone box is 3.

You Are Designing a Horizontal Distribution System That Will Have