Some regular National Electrical Code (NEC) users may not have noticed major changes in the 2014 and 2017 editions dealing with the emergency and standby power requirements in Article 700, Emergency Systems; Article 701, Legally Required Standby Systems; and Article 702, Optional Standby Systems. Not being familiar with these changes could be costly for an electrical engineer or an electrical contractor that does design/build projects. Where the updated version is not used or these items are missed, a building’s emergency or standby system could be seriously affected.
The 2014 NEC added Section 700.8 and requires a listed surge protective device (SPD) to be installed in or on all emergency systems switchboards or panelboards. Article 285 covers SPDs for normally grounded systems that are 1,000 volts (V) or less. These devices are not permitted for systems that are greater than 1,000V, ungrounded systems, impedance grounded systems, or corner grounded delta systems, unless listed specifically for use on these systems. These devices also are not permitted where the SPD rating is less than the maximum phase-to-ground voltage at the power frequency available at the point of application, or, in this case, at each emergency panelboard or switchboard.
The SPD must be listed, connected to each ungrounded system conductor and marked with a short-circuit current rating. It shall not be installed at a point on the system where the available fault current is higher than the device’s fault-current rating.
Section 230.82(4) permits Type 1 SPDs to be installed on a service disconnect’s supply side or on the load side of the first overcurrent device at the service and at emergency system switchboards and panelboards. A Type 1 or a Type 2 can be installed downstream from the service. A surge arrestor, based on Article 280, can be installed on the line or load side of greater than 1,000V service equipment and downstream from that equipment on switchboards operated at greater than 1,000V. The purpose is to provide surge protection at equipment, especially solid-state equipment, susceptible to transient voltage from utility company power and from transients generated within the facility.
In the 2017 NEC, subsections 700.3(C) for emergency systems and 701.3(C) for legally required standby systems were revised from battery maintenance to overall maintenance. This requires system equipment to be maintained in accordance with the manufacturer’s instructions and industry standards. While this change will help ensure the proper maintenance instructions are given to the facility owner, the owner will be responsible for ongoing maintenance after signing off on and accepting the installation.
In the 2017 NEC, 700.10(A) was revised to require emergency circuits to be permanently marked as a component of an emergency circuit or system by one of two methods. The first method has been in the NEC for quite some time and applies to boxes and enclosures, including transfer switches, generators and power panels. The method calls for emergency circuits to be permanently marked as a component of the emergency circuit or system.
The second method is new and applies where boxes or enclosures are not encountered. Exposed cable or raceway systems are to be permanently marked as a component of an emergency circuit or system at intervals not to exceed 25 feet.
Also new within 700.10(A) is a requirement that all receptacles supplied by the emergency system must have a distinctive color or marking on the receptacle cover plate, or the receptacle must have a distinctive color, such as red identifying the receptacle as an emergency receptacle. This identification for emergency receptacles has been a requirement in Article 517 for healthcare facilities and in 708.10(A)(2) for critical operations power systems, but it is new in Article 700.
Transfer equipment covered in 700.5(E) for emergency systems, 701.5(D) for legally required standby systems, 702.5 for optional standby systems, and 708.24(E) for critical operations power systems must have the short-circuit current rating of the transfer equipment—based on the specific overcurrent protective device and settings protecting the transfer equipment—field-marked on the transfer equipment exterior. The EC is responsible for determining the fault current at that location and field-marking the transfer equipment. The transfer switch must have a short-circuit current rating at least as high as the amount of available fault at that point in the system.
All these changes are critical for successful system operation.