Why every panel needs a surge protective device and what contractors need to know

A surge protective device (SPD) diverts current spikes to ground and clamps surge voltages before they reach connected equipment, protecting circuits downstream of the panel. The 2020 NEC (Article 230.67) now requires an SPD to be installed at all dwelling unit services. For the 2023 code year, Articles 230.67 and 215.18 require SPDs to be installed at services and all feeder panels for dwelling units, dormitories, hotels and motels, and nursing home patient sleeping rooms.

For contractors, this means surge protection has moved from an optional upsell to a code requirement, and from a code requirement to a real customer conversation. Knowing how to explain, install, and inspect a surge protective device is now part of the job on almost every service change.

Why surge protective devices matter in modern panels

Today’s residential panels do more than distribute power. They support smart panels, breakers, home energy management systems (HEMS), EV charging, solar and battery storage integration, and connected HVAC and appliances. All technology that depends on clean, stable voltage to function correctly.

A surge is a brief burst of overcurrent and overvoltage, typically lasting less than a few microseconds. That short window can be enough to destroy sensitive electronics instantly or can degrade them slowly over repeated events.

According to the Electrical Safety Foundation International (ESFI), a typical building experiences over 150 power surges per month. The National Electrical Manufacturers Association (NEMA) estimates that 60–80% of those surges originate inside the home, from HVAC compressors, motor starts, or appliance cycling, rather than from external lightning.

A hardwired surge protective device installed at the service entrance, feeder panel, or disconnect provides an efficient way to protect appliances and electronics. That means an SPD installed at a panel will protect downstream circuits and connected devices from the panel bus to the outlet, not just what is plugged into one specific strip.

“What’s changed in the last five years isn’t surge protection technology—it’s what’s in and  downstream of the panel. Smart panels, EV chargers, heat pumps, solar inverters: all of it depends on protection from surge voltages and currents. Contractors who treat the SPD as a core part of the service, not an accessory, are specifying for the system their customer actually has today,” says Eric Marshall, Surge Protection Product Manager at Schneider Electric.

The NEC now requires surge protective devices

The National Electrical Code (NEC), published every three years by the National Fire Protection Association (NFPA), now requires surge protection in most residential services and an expanding list of commercial and multi-family applications.

2020 NEC—Article 230.67: All services supplying dwelling units require a Type 1 or Type 2 surge protective device. The requirement also applies when an existing service is replaced, making service changes a natural moment to specify an SPD.

2023 NEC—Articles 230.67 and 215.18: Expanded from dwelling unit services to include services for dormitory units, guest rooms and suites in hotels and motels, and patient sleeping rooms in nursing homes and limited-care facilities. In addition, Article 215.18 requires SPDs to be installed at feeder panels serving those same occupancy types. As a verification of an SPD’s ability to repeat its protective capabilities as defined in Article 100, SPDs must be listed with a minimum nominal discharge current (In) rating of 10 kA.

In multi-family buildings, the main service needs to be surge-protected as well as feeder load centers or panels located within individual dwelling units, per Article 215.18.  The NEC allows for SPDs to be installed within or adjacent to the panel being protected. Confirm placement with your local inspector before specifying.

Adoption varies by state. Some jurisdictions adopt new NEC editions within months of publication; others lag by one or two cycles. Even in states that have not yet adopted the 2023 edition, the equipment being protected has not become less sensitive. Surge protection remains a best practice regardless of local code status.

Contractors should confirm their state’s current NEC adoption status before quoting and should offer whole-home SPDs proactively on service changes where they are not yet required by law.

Common myths about surge protective devices

Myth 1: An SPD is a one-time-use device.

SPDs don’t “reach end of life due to the first lightning strike,” but they also don’t last forever. All MOV-based SPDs degrade gradually over their service life as they absorb surge events. How long an SPD lasts depends on the environment, kA rating, and installation quality. Some devices last a few years in harsh conditions, while others keep working after decades. Specifying SPDs with larger surge current capacities and protection status indicators is how contractors extend protection and give customers a clear replacement signal.

Myth 2: If the protection status indicator light is on, everything is fine.

The LED is a protection status indicator providing a visual status that power is present and surge protection is active. A quality surge protective device is designed to handle multiple surge events over its service life. In high-surge regions, annual inspection of the protection status indicator is recommended.

Myth 3: A power strip is enough.

A basic power strip protects only what is plugged directly into it, and many strips sold as “surge protection” offer no meaningful surge suppression at all. A whole-home surge protective device installed at the service and feeder panels protects every circuit simultaneously, which is the difference between protecting one outlet and protecting the entire electrical system at the source. If coaxial or telephone wires enter the location, they should also have protection installed. These entry points can also provide a surge entry path to damage equipment connected to those wires that isn’t protected by the panel-connected SPD.

Installing a surge protective device correctly

Even the best surge protective device will not perform properly if it is installed incorrectly. Field best practices:

• Keep conductor length as short and straight as possible
• Avoid sharp bends in SPD leads
• Install as close as possible to the service entrance
• Follow the manufacturer’s torque and wiring specifications

SPD lead length has a direct impact on let-through or clamped voltage during a surge event. Shorter leads mean better clamping performance and less residual voltage reaching downstream equipment.

Square D plug-on neutral (PoN) SPDs eliminate the wiring step entirely. They plug directly onto the neutral bar of a QO or Homeline load center using two-pole spaces, with no field wiring needed. That is one less install variable that can go wrong.

Inspection, ROI, and long-term value

A surge protective device is not a set-it-and-forget-it installation. In high-surge areas such as coastal regions, high-lightning zones, or sites with heavy motor loads, annual inspection of the SPD’s protection status indicator is recommended.

According to NEMA, the average home contains $15,000 worth of equipment vulnerable to power surges, and ESFI reports that a typical building experiences more than 150 surges per month.

A single surge event on a $5,000 HVAC system can easily exceed the cost of a whole-home SPD many times over. For the customer, an SPD can pay for itself the first time it absorbs a meaningful surge event.

For contractors, annual SPD inspection is a low-friction service offering that strengthens customer relationships, identifies end-of-life devices before they become customer problems, and converts one-and-done service calls into recurring touchpoints.

“Recommending annual surge protection inspection is one of the simplest ways to turn a single service call into a long-term customer relationship. The device protects the equipment downstream; the inspection is what protects the relationship,” says Eric Marshall.

Surge protective devices are foundational, not optional

As residential electrical systems become more connected and more AI-ready, every smart product the homeowner installs depends on clean, stable voltage at the panel. A whole-home surge protective device protects not only the panel hardware but also every dollar the homeowner has put into smart appliances, EV charging, solar and storage, and connected HVAC.

As your energy technology partner, Schneider Electric offers a full Square D surge protective device range, from plug-on neutral SPD to the universal HEPD series, which connects to any brand of residential load center.

This article is for informational purposes only and does not constitute professional electrical, legal, or code-compliance advice. Always consult your local authority having jurisdiction (AHJ) and the most current adopted NEC edition for your state before specifying or installing electrical equipment. Square D, Homeline, QO, and HEPD are trademarks of Schneider Electric.