Change Summary

• The new article, “Energy Storage Systems,” applies to all permanently installed energy storage systems (ESS) operating at over 50-volts ac or 60 volts dc that may be stand-alone or interactive with other electric power production sources.
  Energy Storage Systems is a specialized area of work for electrical professionals and beyond the scope of this Captain Code document. However we provide this brief mention here to inform our readers of this emerging technology. If you are involved in this work we recommend reading article 706 in its entirety in NEC 70.

Expert Analysis

An Energy Storage System (ESS) is defined as “one or more components assembled together capable of storing energy for use at a future time.” An ESS can include batteries, capacitors, and kinetic energy devices (e.g., flywheels and compressed air). They can have ac or dc output and can include inverters and converters.