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Code Q&A

Aug 27, 2007 10:33 AM, By Mike Holt

Q. What is the minimum service drop clearance above a roof?

A. In general, overhead service conductors must maintain a minimum vertical clearance of 8 feet above the surface of a roof for a minimum distance of 3 feet in all directions from the edge of the roof [230.24(A)]. If the slope of the roof exceeds 4 inches for every 12 inches, 120/208V or 120/240V conductor clearances can be reduced to 3 feet over the roof [230.24(A) Ex 2].

If the service mast is used in a through-the-roof application, 120/208V or 120/240V conductor clearances can be reduced to 18 inches over the overhang portion of the roof [230.24(A) Ex 3]. There must not be more than 6 feet of service-drop conductors over the overhang portion of the roof and the service mast can’t be located more than 4 feet from the edge of the roof overhang measured horizontally.