The National Electrical Code® (NEC) includes several code requirements related to surge protective devices.  The specific requirements depend on your state’s code adoption year. 

According to the NFPA, as of February 1, 2023, the 2020 NEC is in effect in twenty-five states, the 2017 NEC is in effect in seventeen, the 2014 NEC is in effect in two states and the 2008 NEC is in effect in two states.  As of that same date, five states have begun the process to update from the 2020 to the 2023 edition.

To determine the current edition of the NEC being used in your state, see the NEC in effect map.

Summary: The 2020 NEC featured a new article related to surge protection.  Article 230.67 now requires all services supplying dwelling units to be provided with a surge protective device (SPD), as an integral part of equipment or located immediately adjacent. The SPD must be a Type 1 or Type 2 SPD. This requirement applies to residential service equipment being replaced as well.

Read the full code below:

Service Equipment – General
230.67 Surge Protection.

(A) Surge-Protective Device.

All services supplying dwelling units shall be provided with a surge-protective device (SPD).

(B) Location.

The SPD shall be an integral part of the service equipment or shall be located immediately adjacent thereto.

Exception: The SPD shall not be required to be located in the service equipment as required in (B) if located at each next level distribution equipment downstream toward the load.

(C) Type.

The SPD shall be a Type 1 or Type 2 SPD.

(D) Replacement.

Where service equipment is replaced, all of the requirements of this section shall apply.

* As per the NEC, a dwelling unit is a single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation.

Summary:  The 2023 NEC expands upon Article 230.67 in the 2020 NEC. Whereas the 2020 NEC required SPDs in “dwelling units”, the 2023 NEC added dormitory units, guest rooms and guest suites of hotels and motels, as well as areas of nursing homes and limited-care facilities used exclusively as patient sleeping rooms to areas requiring an SPD.

Read the full code below:

Service Equipment – General
230.67 Surge Protection.

(A) Surge-Protective Device.

All services supplying the following occupancies shall be provided with a surge-protective device (SPD):

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

(B) Location.

The SPD shall be an integral part of the service equipment or shall be located immediately adjacent thereto.

Exception: 

The SPD shall not be required to be located at the service equipment as required in 230.67(B) if located at each next level distribution equipment downstream toward the load.

(C) Type.

The SPD shall be a Type 1 or Type 2 SPD.

(D) Replacement.

Where service equipment is replaced, all of the requirements of this section shall apply.

(E) Ratings.

SPDs shall have a nominal discharge current rating (ln) of not less than 10kA.

There are several other places surge protective devices are referenced in the National Electrical Code, with references to the 2023 NEC below:

Other locations requiring surge protection…

• 409.70 – Industrial Control Panels
  • Safety circuits for personnel protection that are subject to damage from surge events shall have surge protection installed within or immediately adjacent to the control panel.
• 551.72(E) – RV Park Distribution Systems (allowed, but not mandatory)
  • The use of listed surge protective devices shall be permitted.
  • Informational Note: Use of multiple autotransformers on the load side of RV pedestals, supplied by a single feeder, can result in increased current on the RV park or campground distribution system.
• 620.51(E) – Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts, and Stairway Chairlifts
  • Where any of the disconnecting means in 620.51 has been designated as supplying an emergency system load, a legally required system load, or a critical operation power system load, a listed SPD shall be installed.
• 645.18 – Critical Operations Data Systems
  • A listed surge-protective device (SPD) shall be installed for critical operations data systems in accordance with Part II of Article 242.
• 694.7(D) – Wind Electric Systems
  • A listed surge protective device shall be installed between a wind electric system and any loads served by the premises electrical system. The SPD shall be permitted to be a Type 3 SPD on the circuit serving a wind electric system or a Type 2 SPD located anywhere on the load side of the service disconnect. SPDs shall be installed in accordance with Part II of Article 242.
• 695.15 – Fire Pumps
  • A listed surge protective device (SPD) shall be installed in or on the fire pump controller.
  • Informational Note: See UL 1449-2021, Standard for Surge Protective Devices, for proper application of SPD types.
  • Exception: Surge-protective devices shall not be required in or on a fire pump controller for diesel fire pumps.
• 700.8 Emergency System Switchgear, Switchboards, and Panelboards
  • A listed SPD shall be installed in or on all emergency system switchgear, switchboards, and panelboards.
• 708.20(D) – Critical Operations Power Systems
  • Surge protection devices shall be provided at all facility distribution voltage levels.
• 760.33 – Fire Alarm Control Panels
  • A listed surge-protective device (SPD) shall be installed on the supply side of a fire alarm control panel in accordance with Part II of Article 242.

Article 242 of the 2023 NEC describes where each SPD type can be installed…

242.13 Type 1 SPDs

Type 1 SPDs shall be installed in accordance with 242.13(A) and (B).

(A) Installation

Type 1 SPDs shall be permitted to be connected in accordance with one of the following:

•(1) To the supply side of the service disconnect as permitted in 230.82(4)

•(2) As specified in 242.14

(B) At the Service

When installed at services, Type 1 SPDs shall be connected to one of the following:

•(1) Grounded service conductor

•(2) Grounding electrode conductor

•(3) Grounding electrode for the service

•(4) Equipment grounding terminal in the service equipment

242.14 Type 2 SPDs

Type 2 SPDs shall be installed in accordance with 242.14(A) through (C).

(A) Service-Supplied Building or Structure

Type 2 SPDs shall be connected anywhere on the load side of a service disconnect overcurrent device required in 230.91 unless installed in accordance with 230.82(8).

(B) Feeder-Supplied Building or Structure

Type 2 SPDs shall be connected at the building or structure anywhere on the load side of the first overcurrent device at the building or structure.

(C) Separately Derived System

The SPD shall be connected on the load side of the first overcurrent device in a separately derived system.

242.16 Type 3 SPDs

Type 3 SPDs shall be permitted to be installed on the load side of branch-circuit overcurrent protection up to the equipment served. If included in the manufacturer’s instructions, the Type 3 SPD connection shall be a minimum 10 m (30 ft) of conductor distance from the service or separately derived system disconnect.