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NEC in the Facility

Nov 20, 2009 4:20 PM

Provide adequate overhead clearances from buildings to overhead service conductor final spans. The NEC doesn't allow you to run these conductors under openings through which materials might move or where they might obstruct such openings [230.9].

The NEC also requires that conductors maintain a vertical clearance of 3 ft from doors, porches, balconies, etc., and from windows that open. That distance isn't nearly as much as it might seem. If you want to ensure you're protecting someone who's standing in a door or opening a window, allow for that additional distance.

Don't fall into the trap of optimizing space or reducing installation costs by using the NEC minimums as your design criteria. Instead, look at your actual conditions, both present and future. For example, consider maintenance clearances for roof attachments such as facades, lightning protection, signage, and lighting. If that final span runs over an accessway, allow enough height for service vehicles.

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