National Electrical Code, 2023 Edition

NFPA 70®, National Electrical Code® (NEC®), sets the foundation for electrical safety in residential, commercial, and industrial occupancies around the world. The latest NEC 2023 Sections detail the requirement of surge protection devices (SPDs) in specific applications.

Article 242 provides the general requirements, installation requirements, and connection requirements for overvoltage protection and overvoltage protective devices. Part II covers surge-protective devices permanently installed on premises wiring systems of not more than 1 kV, nominal. Part III covers surge arresters permanently installed on premises wiring systems over 1 kV, nominal.

The 2020 NEC introduced a new requirement in Section 230.67 to have a Type 1 or Type 2 surge protective device (SPD) for dwelling unit services. Additionally, an SPD is required when an existing service is replaced.

Section 230.67 (A) – Dwellings
All services supplying the following occupancies shall be provided with a surge-protective device (SPD)

Modern appliances and safety devices such as GFI outlets, smoke alarms, and other equipment are vulnerable to surges, and their damage or failure to operate is compromised without proper surge protection.

In the 2023 NEC, surge protection is now required for services supplying the following specific dwelling types:

• Dwelling units
• Dormitory units
• Guest rooms and guest suites of hotels and motels
• Areas of nursing homes and limited-care facilities used exclusively as patient sleeping rooms

Similar code language was added in Section 215.15 for feeders, and Section 225.42 which covers outside branch circuits and feeders.

Code Exception 230.67 (B): SPD is not required at service entrance panel if you install an SPD at the downstream sub-panels towards the load.

Also, the 2023 NEC has added the to this article the part (E) Ratings, “SPDs shall have a nominal discharge current rating (In) of not less than 10kA.”

Additional Explanation of Type 1 and Type 2 Surge Protective Devices:

• Type 1 devices are typically intended to be installed before the main breaker in the load center.
• Type 2 devices are installed after the main breaker in the load center.
• Type 1 SPDs are intended for installation between the secondary of the service transformer (utility) and the line side of the service equipment overcurrent device, as well as the load side — including watt-hour meter socket enclosures — and are intended to be installed without an external overcurrent protective device.
• Type 1 devices are dual rated for Type 2 applications as well, providing the highest ratings available for installation at the service entrance.
• Type 2 SPDs are intended for installation on the load side of the service equipment overcurrent device, including SPDs located at the branch panel.

Existing requirements

• Section 708.20 – Critical Operations Power Panels: Surge protection devices shall be provided at all facility voltage distribution levels for critical operation power systems (COPS).
• Section 645.18 – Critical Operations Data Systems: Surge protection shall be provided for Critical Operations Data Systems.
• Section 620.51 (E) – Emergency Systems: Where any of the disconnecting means in 620.51 has been designated as supplying an emergency system load, surge protection shall be provided.
• Section 700.8 – Emergency Systems Power Panels: A listed SPD shall be installed in or on all emergency systems switchboards and panel boards.
• Section 670.6 – Industrial Machinery: Industrial machinery with safety interlock circuits shall have surge protection installed.
• Section 694.7 (D) – Wind Power Generation: A surge protection device shall be installed between a wind electric system and any loads served by the premise electrical system.
• Section 695.15 – Fire Pumps: A listed surge protection device shall be installed in or on the fire pump controller.