Industry Article

Best in Class: Class 4 Power Benefits and Applications

Learn more about the Class 4 power capabilities and how this new circuitry can enable innovative technologies.

There’s been much talk of late about the National Fire Protection Association’s (NFPA) addition of a new class of power (Class 4) to the National Electrical Code (NEC) and its potential for powering the technology of the future. For years, power demands across industries have been rising, and engineers, innovators, and inventors have been itching for a way to meet those rising demands safely. Class 4 circuitry offers that alternative, and its potential impact cannot be overstated. 

With the 2023 edition of the NEC and Underwriters Laboratories (UL) guidance on the technology, the promise of Class 4 power is already being explored across industries. Although the road to widespread Class 4 deployments will come with potential challenges, power engineers are already working to address concerns and ready the technology to make Class 4 deployments a reality in the near future.


A New Approach in Class 4 

Although the NFPA updates the NEC every few years, the addition of Class 4 to the manual represents a significant departure from previous wiring methods. Since the organization began outlining power classes, the foundational principle driving electrical installation regulations has been to limit circuits’ maximum power and voltage capacities. Classes 1, 2, and 3 rely on this approach to help ensure safety and mitigate the risk of property or system damage.  

While limiting power and voltage capacities has effectively reduced the risk of harm and damage, it has also limited potential innovation. For decades, the 100 VA limitations of Class 2 and Class 3 circuitry have put technologies that require large loads at high voltages out of reach. With Class 4 power architecture, those designs may now become a reality.


Fault-Managed Power Systems

Class 4 is built around fault-managed power systems (FMPS) instead of simply limiting currents and voltages. FMPS technology monitors for interruptions hundreds (or thousands) of times each second and can differentiate between loads and human interference; respond to line-to-line and line-to-ground faults; identify series and parallel arcs; and recognize line-to-line and series-resistive faults. The systems are designed to limit current flow during a fault condition rather than limiting the power available in the circuit altogether, cutting the power to the circuit in milliseconds to seconds (depending on the fault current).


Class 4 Potential Adopters 

With Class 4 given the NFPA’s official nod, engineers, inventors, and industrial designers are looking forward to exploring its myriad applications. Let’s take a closer look at three industries that are likely to be early drivers of Class 4 adoption:


The telecoms sector will likely benefit from Class 4 power as it pursues the expansion of 5G networks. Communications service providers (CSPs) are constantly seeking solutions that can help ease financial, efficiency, and logistical burdens—and that is true with the 5G buildout as well as they work to power their 5G small cells and other networking equipment.

Class 4 can help as its unique properties allow it to deliver larger loads over longer distances than its predecessors safely. That will enable telecommunications service providers to deploy indoor and/or outdoor distributed antenna systems (DAS), fixed wireless access (FWA) systems, and private networks for enterprise use within office buildings and for commercial use by the public. For FWA deployments, utilizing centralized Class 4 power distribution paired with fiber may help hasten the installation of 4G and 5G small cells to increase capacity and coverage rapidly.

Networking and Data Centers 

The same can be said for data center design. These facilities (shown in Figure 1) use a remarkable amount of power, and demand is only growing. As data centers become larger and their applications become more mission-critical, operators and architects must determine how to increase their efficiency and deliver large enough loads to keep the facilities running at full capacity.


Data centers that opt to use Class 4 power architectures may be better positioned to increase efficiency.

Figure 1: Data centers that opt to use Class 4 power architectures may be better positioned to increase efficiency.


As such, engineers have been discussing the benefits of transitioning data center facilities to DC power. Leveraging DC power more broadly in these facilities could improve energy efficiency by eliminating conversion steps, allowing operators to power servers, storage equipment, and networking equipment more efficiently and reliably. Class 4 may bring operators one step closer to this reality as its design can support direct currents more easily than other wiring methods – without the need for conduit. 

As the push toward DC-powered data centers continues, FMPS could help operators embrace the change more quickly in both brown- and greenfield deployments. For example, data centers that use Class 4 architecture will be better positioned to deploy LED lighting without needing AC-to-DC conversion. Furthermore, data center loads (e.g., servers, storage, and networking equipment) can be DC-powered without rectification, leading to both capex and opex savings.

Furthermore, the FMPS-based safety features could help reduce risk to those working with high-powered equipment, negating the need for certified technicians and specialized accessories such as high-voltage DC power outlets and connectors.

Commercial Buildings 

Class 4 power’s capabilities make it a compelling choice for large-scale buildings like stadiums, airports, and academic and healthcare campuses. These buildings are expansive, have massive energy demands, and in many cases, need to be “always on.” 

The ability to reliably and safely transmit high voltages and currents across long distances will allow architects and planners to reimagine their approach to designing these landmark buildings. If used to support LED lighting and on-premises networking equipment, Class 4 could boost efficiency in the same ways it might work in data centers. 

Furthermore, as discussed above, Class 4 could do more than change building designs when used to support DAS and FWA at the building level. It could also facilitate more satisfying experiences for visitors by supporting the widespread use of “smart building” technology (shown in Figure 2). 


Class 4 power could help support the widespread use of smart building technology.

Figure 2: Class 4 power could help support the widespread use of smart building technology.


Challenges Facing NEC Class 4 

Challenges to these deployments will surely arise, as they often do when new models emerge. Topping the list will be knowledge gaps. Electricians, engineers, architects, and other decision-makers will need time to learn how to use Class 4 power. Limited equipment availability may also present a barrier to adoption. Manufacturers and designers will face a similar learning curve as they work to develop and manufacture the solutions needed to build high-voltage, fault-managed circuits at scale.

Still, these concerns are minor compared to the innovative technologies Class 4 power could enable. As the novelty of the NEC’s newest power class wears off, speculations about possible applications will give way to tangible solutions that may revolutionize how we power tomorrow’s cities, communication networks, and gathering places.