Class 4 power: Coming soon to tech near you

Article By : Raj Radjassamy

Class 4 power releases engineers from old power limitations, enabling new power architectures for data centers, mobile networks, and other power-hungry technologies.

For decades, the guiding principle of safe electrical installation has been to mitigate risks by limiting a circuit’s maximum power and voltage. However, with the power demands of modern computing, robotics, and communications equipment consistently rising, putting limitations on circuitry’s capacity is increasingly limiting innovation.

In response to the need for higher-power options for in-building applications and to support critical infrastructure, the national fire protection association (NFPA) is planning to define a new class of power in the coming months, and it takes a different approach to mitigating the risks at higher power. The addition of Class 4 circuitry to the national electrical code (NEC) is slated to take place early next year, and Underwriters Laboratories (UL) is working to develop safety testing guidelines for new installations.

With two of the most prominent electrical safety organizations on board and with the rollout of Class 4 power throughout the U.S., innovation across sectors is poised to take off as the strict limits on the maximum load capacity fall away.

Limiting power limits potential risks … and rewards

The potential of Class 4 power to transform power architectures cannot be understated. However, the context in which the technology will be introduced is important to understand its potential impact. Classes 1, 2, and 3 circuits have all been defined in the NEC for some time now. Each class has its own limitations on output current, voltage, range, and wiring specifications, but the idea behind them all is the same: limiting power limits the risk of fire and shock to humans.

Although the NEC classification includes three options, Class 2 has emerged as the most common alternative to traditional wiring methods for environments in which electricity might pose a significant risk. This is due to Class 2’s focus on mitigating both fire and shock rather than one or the other. Per NEC guidelines, Class 2 circuits are those that are wired between the load side of a Class 2 power source and connected equipment. They must use in-wall rated wiring for permanent installation, be wired to power sources with ratings of less than 100 volt-amps (VA) and voltages not exceeding 60 volts (V) DC and be installed in dry environments in non-hazardous locations (Figure 1).

Figure 1 A Master in server clamp crimps electrical contacts.

The above-described specifications are very effective at protecting human life and property, but they come with certain caveats. Most notably, they limit the distance power can travel before the voltage drops below the minimum input voltage of the load. Power distributed via Class 2 circuitry can only cover distances of approximately 500 to 5,000 feet, depending on the load, operating voltage level, and more importantly, the wire size (AWG) used in the deployment. That’s a significant constraint on electrical engineers and infrastructure designers. Limiting capacity in this way means that certain applications have been out of reach, and that’s a growing problem as data centers, mobile networks, and other power-hungry technologies are becoming mission-critical to progress.

How class 4 does it differently

Where Classes 1, 2, and 3 relied on throttled capacities to mitigate electrocution and fire risk, Class 4 power takes an alternative approach. Rather than limiting power to reduce risk, Class 4 circuits use fault-managed power systems (FMPS) to help ensure the safety of those who work with and around them. These systems leverage advanced technology to continuously monitor for faults that could pose risks to people and property while delivering large loads at a maximum voltage of 450 V.

FMPS’ advanced sensing, monitoring, and control capabilities can identify a wide range of faults. The technology at work behind the scenes checks for problems hundreds (or even thousands) of times each second and can differentiate between different kinds of faults to react accordingly. FMPS’ fault-detecting technology 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. If any faults occur, the FMPS technology shuts down the circuit, effectively eliminating the risk of shock and fire.

Class 4 circuitry can be configured for point-to-point or bus topology, making it flexible for use across many applications. Point-to-point configurations connect a single power source to a single powered device using at least one cable pair, while bus configurations can connect a power source to multiple devices with one or more cable pairs, making the latter effective for 5G and telecommunications uses. Regardless of which topology a Class 4 circuit leverages and the equipment’s intended end-use, all circuitry within the class leverages similar FMPS mechanisms.

How Class 4 Will Power 5G

The need for a way to safely deliver larger loads reliably and over longer distances has become more apparent as technology has advanced. While the limitations of Class 2 circuitry may have been frustrating to power engineers in days past, it’s now impeding the progress of innovation—and Class 4 circuitry being introduced to the NEC represents a moment filled with potential for industries across sectors. Soon, it may be the default design for mission-critical systems like power distribution infrastructure, distributed antenna systems, passive optical networks, and systems that use PoE switches (Figure 2).

Figure 2 Different bright colors electric wires installed on the constructions of industrial building.

5G networks and related technologies, in particular, will benefit from the use of bus-configured FMPS circuits. As communication service providers (CSPs) have pushed to expand their networks at a break-neck pace to meet the growing demand for 5G connections, the complexity of powering the equipment that runs them has emerged as a significant obstacle. 5G small cell radios have higher power demands than those used for previous generations and need to be deployed on a wide scale. As such, CSPs and power engineers have been looking for a more efficient, cost-effective, and customizable power solution to accommodate 5G networks’ unique needs.

Integrating Class 4 circuitry into these plans provides a solution as these designs can offer power for a diverse range of high-frequency radios. An FMPS could, theoretically, use one high-capacity power supply to power all the necessary equipment in a building. And it may be able to do it while still safe guarding all the safety requirements related to high voltage circuitry. These capabilities could bring 5G’s most exciting and advanced use cases—like self-driving cars, wireless broadband, edge computing, and more—to life.

Power is just the beginning

Solving 5G’s power problems is just one example of how FMPS will facilitate innovation. Although the technology has been in development for some time now, the full range of its applications has yet to be discovered. As the FMPS technology matures, more and more sectors are likely to adopt this approach to drive innovation within their industries.

It has the potential to fundamentally change how engineers and architects design power infrastructure, and it’s likely to be integrated into large, power-hungry facilities like stadiums, hotels airports, and more. While power engineers and electricians will likely be the first to see changes, its impacts will soon be felt across industries—from retail to travel, entertainment, and beyond.


This article was originally published on EDN.

Raj Radjassamy, director, product management for 5G solutions, ABB Power Conversion.


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