Now that the 2014 edition of the National Electrical Code® (NEC®) has been published, IAEI Magazine from the International Association of Electrical Inspectors examines what’s new in the requirement for arc energy reduction in Section 240.87.
This section was added to Article 240 in the 2011 edition of the NEC. It required the use of Zone Selective Interlocking (ZSI), differential relaying, energy-reducing maintenance switching or an approved equivalent means where a circuit breaker without an instantaneous trip function is used. The motivation was to protect electrical workers better from the arc-flash hazard when a short time delay is used to slow down the operation of a circuit breaker to achieve coordination in an electrical system.
Click here to read the full article from IAEI magazine that takes an in-depth look at the changes and what they mean.
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