The terms Fault Managed Power (FMP), Digital Electricity, and Class 4 are often used interchangeably in power delivery. They’re related, but not the same thing. For companies that source and install cable, knowing the difference between all three terms matters.
The Problem FMP Solves
For years, power distribution came down to two options: traditional electrical infrastructure or low-voltage power like Power over Ethernet (PoE). Traditional infrastructure was expensive and inflexible, and PoE was too weak for most applications. FMP closes that gap by delivering strong power without the cost and rigidity of traditional infrastructure.
FMP: The Concept
Standard, low-voltage classifications (Class 2 and Class 3) cap power output at the source. Instead, FMP continuously monitors the line for faults and cuts power off in milliseconds if something is wrong. That safety-first approach lets FMP deliver higher voltage and power than older, low-voltage standards can.
Digital Electricity: The Proof
Digital Electricity is Voltserver’s specific implementation of FMP. It sends power bursts (500 times per second), running a safety check between each one. If something goes wrong—like accidental human contact, a short circuit, or a ground fault—the system shuts down instead of sending another burst. DE was among the first proven FMP systems to prove that the concept actually works at scale.
Class 4: The Code Classification
Class 4 is the classification the 2023 National Electric Code (NEC) created for FMP systems. Rather than mandating a specific engineering approach, it limits how much energy a fault can deliver. This sets a safety outcome that every FMP system can achieve. As long as it meets the right requirements, any FMP system can qualify as Class 4, regardless of how it was built.
Comparing Class 2, Class 3, and Class 4
| Class 2 | Class 3 | Class 4 | |
| Power limit | Capped at the source | Capped at the source | Limited during fault events |
| Safety method | Limits the energy current | Limits the energy current | Active fault monitoring |
| Power delivered | Low (PoE range) | Medium | High (supports long-distance power runs) |
| Distance capability | Limited | Limited | Long distance without power loss |
| Installation | Simple, low-voltage rules | Simple, low-voltage rules | Once certified, it’s installed the same way as Class 2 and Class 3 |
| Use cases | PoE devices and sensors | Low-voltage equipment | Data centers, manufacturing, stadiums |
Note—Digital Electricity isn’t a separate classification, it’s a specific implementation that qualifies as Class 4.
Understanding the classification is one thing. Deploying it is another. Once a system qualifies as Class 4, the next question companies have to answer is: Who is qualified to install it?
Who Can Install FMP Systems?
A common question surrounding FMP systems is whether only certified electricians can work with them. According to the FMP Alliance, that decision is ultimately made by local jurisdictions.
“Your local building jurisdiction really determines what work a contractor is licensed to do,” Ronna E. Davis, secretary for the FMP Alliance, shared on LinkedIn. “This is based on safety and contractor qualifications.”
According to the National Fire Protection Association (NFPA), the 2023 NEC is currently in effect in 25 states, with adoption still expanding. Since the code is revised every three years, Class 4 recognition is only expected to grow. Davis encourages businesses to pay attention to these local jurisdictions, as they ultimately decide whether a licensed electrician is required or not.
From a technology standpoint, she says, FMP is a relatively safe technology to work with. Many businesses tend to wonder if their electrician needs to have the same safety training as those who work on systems that are more dangerous—Davis says no.
“The answer is technically no,” she explains. “But you do need a qualified electrical professional to install these systems. FMP systems need to be installed professionally, as it requires an advanced skill set.”
FMP is practical to deploy at scale because entry barriers are low, even though the technical rigor behind it is real. It’s worth stepping back to see how the pieces add up.
How FMP, Digital Electricity, and Class 4 Work Together
FMP is the concept, Digital Electricity is the proof, and Class 4 is the code that recognizes it. Companies are no longer forced to choose between strong and safe or between fast installation and long-distance reach. For anyone sourcing and installing cable, that’s the whole point.
