Installing Romex In A 2 Inch Metal Conduit Into A Panel
March 28, 2006
Q: May I install romex in a 2 inch metal conduit that is 24 inches long into a panel without securing the cables within 12 inches of where they enter the panel?
A: The general requirement for cable termination is in 312.5(C). This one sentence rule says: “Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure.” However, there is a long exception for nonmetallic sheathed cable (romex), and it is pretty detailed.
Nonmetallic sheathed cables are permitted to enter the top of a service mounted panelboard through a nonflexible raceway that is not less than 18 inches long or longer than 10 feet.
The cable must be secured within 12 inches of the outer end of the raceway; the raceway must extend directly above the panelboard and cannot penetrate the structural ceiling; a fitting is required at each end of the raceway to protect the cables from abrasion and the fittings must remain accessible after installation; the raceway must be sealed at its outer end; the cable sheath must be continuous in the raceway and extend into the panelboard beyond the fitting for at least 1/4-inch; the raceway is secured in accordance with the requirements of the applicable article for the wiring method; and the wire fill table in Chapter 9 must be used to prevent cable overfill.
To determine the number of cables permitted in the 2 inch conduit, Note 9 to Table 1 in Chapter 9 requires that multiconductor cables be treated as a single conductor. For cables with oval or elliptical cross sections, the cross-sectional area is based on the major diameter of the ellipse to obtain an equivalent circle diameter.
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