Properly coordinating AC electrical power distribution systems with over-current protective devices can be complex and difficult. It requires integrating different components, technologies, manufacturers, and standards. There is no standard, cookie-cutter approach that can be applied effectively across system designs. And even though selective coordination is about to enter its third NEC* cycle as a mandated requirement — not left to engineering judgment since the 2005 cycle — issues continue circulating about the necessity of mandating it, what constitutes compliance and how other aspects of power system design might be compromised.
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