The Coming Transformation: Why Every Electrician Should Pay Attention to Class 4 Wiring

Introduction: A New Class of Power Is Here

If you've come across terms like Digital Electricity, Fault-Managed Power, UL 1400, or NEC Article 726, you're not alone. What began as a specialized technology is now officially acknowledged in the 2023 National Electrical Code, and it's poised to revolutionize power distribution.

For electricians, this is more than just a buzzword or a manufacturer's gimmick. Class 4 wiring, also known as Fault-Managed Power Systems (FMPS), bridges the gap between the convenience of low-voltage and the capacity of high-voltage. It's set to change the way we install, troubleshoot, and even price electrical work.

What Is Class 4 Wiring?

For many years, we've worked within three NEC circuit classifications: Class 1, 2, and 3. Class 1 deals with standard line-voltage circuits, while Class 2 and 3 are for low-voltage, power-limited systems such as PoE, lighting controls, or communications. These systems limit energy levels for safety, which also restricts the distance and amount of power you can deliver.

Class 4 wiring transforms everything. Instead of restricting voltage or current, it actively manages the power through real-time fault monitoring. A Class 4 circuit continuously checks for line-to-line, line-to-ground, or touch faults. If an issue arises, it almost instantly halts energy delivery.This "fault-managed" behavior allows you to transmit hundreds or even thousands of watts safely over thousands of feet of cable. In practice, this offers the reach of line voltage with the safety characteristics of low voltage.

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How It Works: Power That Thinks

Traditional power systems deliver a continuous current through conductors, with a breaker or fuse responding after a fault occurs. Class 4 adopts a different strategy.

It transmits energy packets that are continuously verified between the transmitter and receiver. If a fault, short, or contact is detected, the transmitter instantly halts power transmission. This circuit responds in microseconds, much faster than any mechanical breaker.

This “digital power” functionality is what companies like VoltServer refer to as Digital Electricity™. It is safer, more intelligent, and capable of transmitting significant power over long distances without the need for traditional conduit-heavy infrastructure.

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Backed by the 2023 NEC and UL Standards

Class 4 wiring has transitioned from experimental to being part of the code.

• NEC 2023 Article 726 officially defines Class 4 (Fault-Managed) circuits, detailing performance requirements, voltage limits (up to approximately 450 V AC/DC), and approved installation methods.

• UL 1400-1 establishes the safety standards for Class 4 transmitters and receivers.

• UL 1400-2 specifies the construction of cabling and connectors for fault-managed systems.

Together, these documents offer the legal and safety framework for contractors to confidently design, permit, and install Class 4 systems.

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Why Electricians Should Care

This isn’t merely an enhancement of current systems—it’s a transformation in our approach to electrical work. Here’s why it’s important for every electrician:

1. New Project Scopes and Bid Structures

Class 4 systems can often eliminate the need for conduit runs and heavy-gauge wire, allowing projects to be completed with reduced material and labor. You can use hybrid power-and-data cables to connect remote endpoints—such as access points, lighting, sensors, cameras, and displays—without the expense and complexity of multiple AC circuits.

2. Extended Reach and Flexibility

Traditional low-voltage systems are limited to about 300 feet. Class 4 can extend power over a thousand feet or more, enabling you to power remote loads, outdoor poles, or building wings from a central power source.

3. Safety with Power

Fault-managed systems make high-energy distribution safer for both installation and maintenance. Electricians can handle these systems without the same risk of shock associated with line voltage.

4. Training and Tools

Electricians who know how to test, terminate, and commission Class 4 systems will have an advantage. As more general contractors and owners embrace fault-managed designs, trained crews will be more valuable and secure more jobs.

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Real-World Projects: Class 4 in Action

Hard Rock Stadium, Miami

One of the first large-scale implementations occurred at Hard Rock Stadium, where VoltServer’s Digital Electricity system powered remote radio heads across the stadium’s distributed antenna network. Due to long distances and limited installation spaces, traditional AC distribution was impractical. However, Class 4 wiring enabled high power delivery over lightweight cables with real-time fault protection.

Smart Buildings and Campuses

Contemporary facilities such as hotels, universities, and office campuses are starting to adopt fault-managed power for lighting, security, and networked devices. These systems offer safe, centralized DC power with fewer panels, reduced conduits, and quicker deployment times.

Other Early Adopters

Indoor agriculture operations, EV infrastructure projects, and telecommunications networks are also adopting Class 4 for its extended reach and efficiency. Companies like Panduit, Belden, Proterial Cable America, and Remee Wire & Cable now manufacture UL-listed Class 4 components for integration into current systems.

The Companies Leading the Way

• VoltServer — Innovator of Digital Electricity and a key contributor to the NEC Article 726 framework. Their technology is utilized in stadiums, smart buildings, and data networks.

• Panduit — Provides UL-certified Fault-Managed Power Systems (FMPS) with transmitter, receiver, and cable packages for commercial use.

• Belden — Develops Digital Electricity cabling systems for long-distance, high-power, low-risk installations.

• Proterial Cable America & Remee — Create hybrid copper/fiber cable families listed under UL 1400-2 for Class 4 applications.

• The FMP Alliance — An industry group focused on educating electricians, integrators, and AHJs about best practices for Class 4 implementation.

How Electricians Can Prepare

Now is the time to prepare. Here’s how to stay ahead:

• Study the Standards: Review NEC Article 726 and UL 1400-1/-2. Familiarize yourself with the safety requirements, listing rules, and installation variations.

• Consult Distributors: Inquire about the Class 4-listed cables and transmitters they offer. Many leading suppliers now have compatible hardware in stock.

• Train Your Team: Practical experience is crucial. Practice terminating connectors, running cable, and testing circuits.

• Invest in Testing Equipment: Acquire instruments capable of verifying Class 4 operation, including voltage, packet integrity, and fault response.

• Coordinate with AHJs: As this is new, inspectors might be cautious. Provide datasheets, UL listings, and diagrams to demonstrate compliance.

Challenges to Expect

New technologies always present learning challenges. Not every area has implemented the 2023 NEC yet. Inspectors will have inquiries. Equipment ecosystems can be proprietary, and precise field terminations are necessary. However, these challenges are temporary. As your teams gain experience, Class 4 installations will become quicker and more efficient than traditional AC setups.

The Future of Job Sites

In a few years, job sites will transform. Instead of installing heavy conduit to each endpoint, electricians will use smart hybrid cables. Power and data will be transmitted together, simplifying infrastructure. Maintenance will transition from reactive to proactive—fault-managed systems can identify issues before they lead to downtime.

Class 4 technology will seamlessly integrate with energy storage, DC microgrids, and renewable energy generation, leading to smarter, more efficient buildings. As these systems converge, electricians will evolve from installers to power integrators, managing data, energy, and automation as an interconnected ecosystem.

Conclusion: Adaptation is Key for Electricians

Class 4 wiring is not a future concept—it’s already in place, included in codes and implemented in major facilities nationwide. It offers higher power, longer distances, and safer operations, while reducing materials and labor.

Contractors who grasp and adopt this change will lead the next wave of electrical work. Those who don’t will find themselves competing with outdated methods. The trade is evolving, with Class 4 wiring at its core.

In the next article of this series, we’ll examine energy storage systems and how fault-managed power integrates with DC microgrids and on-site batteries—continuing the modernization of the electrical industry.