NEC Introduces New Standards in Surge Protection

The National Fire Protection Agency (NFPA) has released its updated revision (2023) of the National Electric Code (NEC). These changes ensure engineers and electricians stay compliant and maintain safety practices. The NFPA releases new changes and revisions every three years to keep up with the latest technologies and electrical components, and the list is extensive, especially when it comes to power and surge protection in residential, commercial and alternative energy systems.

As strange as it may sound, before the 2023 NEC release, the smallest branch circuit recognized by the NEC for power and lighting loads was just 15 amps! The NEC has now recognized branch circuits at 10 amps, making for a significant shift in the industry. This was probably due partly to manufacturers introducing more energy-efficient lighting systems over the last several years.

NEC Section 210.23, entitled "Permissible Loads, Multiple-Outlet Branch Circuits," permits 10-amp branch circuits to supply one or more of the following loads – lighting outlets, dwelling unit exhaust fans and gas fireplace units.

Regarding servicing and maintaining equipment, the NEC Section 110.17 states that all service and electrical maintenance must be performed by qualified individuals with the proper training. It also emphasizes the need to follow the original equipment manufacturer's instructions and any additional information provided in the equipment listing that's relevant to industry standards. This section is brand new and is essential as it also entails using specific replacement parts.

The latest code will have an impact on both old and new structures in the coming months and years as revisions for cable requirements, EV charging, lighting systems and surge protection will all need to be addressed. Older commercial buildings will have to update or replace existing infrastructure to maintain compliance, which could prove costly depending on the electrical systems. Newer dwellings will lessen that impact as most have adhered to the 2020 NEC codes, which outline the required electrical panels, outlets, surge protection and appliance guidelines.

Surge protection updates

The 2020 NEC codes offered several updates regarding surge protection, and the 2023 update further clarified recent changes. To better understand those revisions, let's look at how surge protection technology works.

These technologies are designed to safeguard electrical and electronic equipment from voltage spikes or surges, which can occur during lightning strikes, utility grid switching, or when high-powered electrical equipment is switched on or off. When a spike or surge occurs, protection technologies can divert excess voltage away from devices and appliances, preventing damage.

Some of those technologies include whole-structure surge protectors, which are installed at the main electrical service panel and can protect any devices connected to the entire building. There are also point-of-use surge protectors, which are plug-in systems designed to protect specific devices and equipment such as PCs, appliances, entertainment systems and more. These protectors work by utilizing components such as MOVs (metal oxide varistors) and gas discharge tubes that conduct excess voltage to the ground.

The 2023 NEC revisions for surge protection now require a Type 1 or Type 2 surge protection device for all services supplying a dwelling, or as the NEC states, “a unit.” These provide a complete and independent living facility for one or more persons and require surge protection devices (SPDs) located within the equipment or adjacent to it. To that end, Type 1 protectors must be placed on the load or service side of the electrical panel, while Type 2 are designed to be placed on the load side only.

A few differences exist between the NEC 2020 and 2023 surge protection requirements. For example, 2020 required SPDs in dwelling units that included multi-family units. NEC 2023 clarified this further to include dormitories, guest rooms and guest suites of hotels and motels, patient sleeping rooms in nursing homes and limited care facilities.

NEC 2023 also added section 409.70, which requires the placement of SPDs to be internal or immediately adjacent to control panels that support personnel protection. It also supports the manufacturer's instructions to keep SPD lead lengths short.

Types of surge protector technologies

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Figure 1. Example of a surge protector device designed to meet the NEC 2023 requirements

There are various Type 1 and Type 2 surge protector technologies that are designed for entire buildings or point-of-use protection. These can include surge-protected breakers, Type 1 single-phase surge protective devices, electric surge suppressors, outdoor transient voltage surge suppressors, control panel surge devices, single-phase meter-load surge protectors and more. There are also electrical components designed to protect against voltage spikes and power surges, such as TDK's ThermoFuse varistors.

Products in TDK's ThermoFuse® series come equipped with monitor outputs and integrated thermal protective components for overvoltage protection. The company's varistors are modified quadratic disk varistors, which connect in series with thermal protection. In the event of an overvoltage, an onboard fuse is activated and separates the varistor from the circuit, which prevents potential damage to any component or PCB equipped nearby. What's more, disconnection from the mains protects against a thermal runaway. They were also designed with flame-retardant materials to prevent fire penetration and damage to the components.

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Figure 2a & 2b. A side-by-side comparison of TDK's ThermoFuse varistors details related voltage ratings, surge protection parameters, energy absorption maximums and more. (Image credit: TDK)

The ThermoFuse series will offer two devices, with the first being the MT30 series (B72230M), which is designed for voltages from 150 VRMS to 750 VRMS, and provides a maximum surge current capability of 25 kA at a pulse form of 8/20 µs.  The second, yet to be released, is the *MT40 series (B72240M), which is designed for voltages from 150 VRMS to 550 VRMS, and provides a maximum surge current capability of 50 kA at a pulse form of 8/20 µs. Potential applications for the ThermoFuse series include photovoltaic inverters, industrial power supplies and inverters, outdoor lighting and telecommunications systems, and Type 1 & Type 2 SPD applications.

Final review of changes and conclusion

While surge protectors garner a large section of the NEC 2023 guide, there are also sections dedicated to additional entries and revisions, including definitions for ground-fault detector interrupters in Article 100, which states, "A device that provides protection for PV system DC circuits by detecting a ground fault and can interrupt the fault path in the DC circuit." This can be helpful for protecting DC circuitry in solar panels.

Surge protection is a widely denoted section within almost every NEC guide and will continue to be revised with new articles introduced as newer technologies are utilized every several years. The National Electric Code (NEC) is updated every three years and changed as necessary to increase safety standards. The changes made in the 2023 NEC relating to electrical surge protection offered more clarity to the changes originally added in NEC 2020.

According to a map from the NFPA, 27 states have adopted mandates outlined in the 2020 version of the NEC, while 12 have updated to the 2017 revision, one has adopted the 2014 version and two have gotten up to speed with the 2008 NEC guide. Four of 50 states have completed their 2023 update process, which has since gone into effect, including Idaho, Wyoming, Minnesota and Rhode Island. 12 others are in the updating stage, while some have completed updates to previous NEC revisions.

“As of July 1, 2023, four states have completed their 2023 NEC update process. Eight states currently using the 2020 NEC and five using the 2017 NEC have commenced the process of revising the statute or administrative rule through which the NEC is updated to reference the 2023 edition; two states currently using the 2017 NEC are in the process of updating to the 2020 NEC and one state currently using the 2008 NEC is in the process of updating to the 2020 edition,” states the NFPA on its website.  “Two states are using the 2014 or 2008 of the NEC and are not in the process of updating the edition currently in use.”

It's important to note that the NEC is not a US law, however, it is commonly mandated as state and local law. That said, the NEC codifies the requirements for safe electrical installations into a single, standardized source. The ‘authority having jurisdiction’ inspects for compliance with these minimum standards and is regionally adoptable for electrical best practices. This means states can adopt the code requirements they feel necessary for retrofitting or inclusion into new dwellings, which can be found on the International Association of Electrical Inspectors (IAEI) website via educational requirements.

Installing SPDs has additional advantages beyond the safety factors outlined in the NEC 2023 guide. Manufacturers and consumers are shifting to increasingly sensitive electronics in everyday appliances and devices. For example, the lifespan of electronic chips found in today's refrigerators, laundry equipment, entertainment centers, and even smart lighting can be extended when an SPD is introduced to combat power surges and voltage spikes. So, it's essential to follow the articles and standards set forth by each new revision of the NEC guide.

*The MT40 series is expected to be released in early 2024.

TDK Electronics