A low-voltage surge protective device (SPD) limits transient voltages by diverting or limiting surge current.
are a cost-effective solution to prevent downtime, improve system and
data reliability, and eliminate equipment damage caused by transient
voltages and surges for power and signal lines. They are suitable for
any facility or load 1,000 volts and below.
An SPD is typically
installed in a power distribution panel, process control system,
communications system, or other heavy-duty industrial systems to protect
against electrical surges and voltage spikes, including those caused by
lightning. Scaled-down versions of these devices are sometimes
installed in residential service entrance electrical panels.
Per the National Electrical Code® (NEC) and American National Standards Institute (ANSI) / Underwriters Laboratories (UL) Standard 1449, SPDs are designated as:
1: Permanently connected to protect insulation levels of the electrical
system against external surges caused by lightning or utility capacitor
- Type 2: Permanently connected to protect the
sensitive electronics and microprocessor-based loads against residual
lightning energy, motor-generated surges, and other internally generated
- Type 3: Point-of-utilization devices that include cord-connected, direct plug-in, and receptacle-type SPDs
NEMA Members provide education and outreach activities for commercial, industrial, and residential users through the NEMA Surge Protection Institute.