Adding Low Voltage SPDs to the NEC®

Adding Low Voltage SPDs to the NEC®

This piece was originally published in the October 2018 issue of electroindustry.

Danny Abbate, Industry Director, Building Infrastructure Division, NEMA

The increased use of electrical equipment in residential, commercial, and industrial settings necessitates protection from external surge sources (like lightning) and internal surges generated by the operation of contactors, relays, breakers, switching of capacitor banks, discharge of inductive devices, or starting and stopping of any electrical load. A surge protective device (SPD) lessens power surges by diverting or limiting surge current and is capable of repeating these functions as specified.

Currently, the National Electrical Code® (NEC) requires SPDs on equipment that protects electronics, including:

  • emergency systems—a listed SPD shall be installed in or on all emergency switchboards and panelboards;
  • elevators, escalators, moving walks, and chairlifts;
  • modular data centers;
  • wind electric systems;
  • industrial machinery; and
  • fire pump controllers.

SPDs are a cost-effective solution to prevent downtime, improve system and data reliability, and eliminate equipment damage caused by transients and surges for both power and signal lines. They are suitable for any facility or load (1,000 volts and below).

Proposals are being developed within NEMA’s Low Voltage Surge Protective Devices Section to add requirements to the NEC to address the recognized need for surge protection in residential dwellings to protect sensitive electronics and systems found in most modern appliances, safety devices (e.g., arc-fault and ground-fault circuit interrupters), and smoke alarms.

NEMA’s Surge Protection Institute offers guidance materials and practical resources designed for engineers, contractors, and inspectors at

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