What is Class 4 Power, and How Does it Differ from PoE?

The National Electric Code (NEC) recently introduced a new class of power that has the potential to change commercial IT infrastructure. Known as “Class 4” power, this is a low-voltage option similar to PoE that can deliver up to twenty times the electricity over longer distances.

The introduction of Class 4 power is worth discussing further. Especially when compared to the power delivery of Power over Ethernet (PoE), Class 4 has some major advantages that businesses may be able to leverage. Let’s dig into the technology and how it can help businesses leverage power distribution advantages in the future.

The 4 Classes of Power

To understand the significance of class 4, it is essential to have basic definitions of each of the 4 classes of power, as defined by the NEC. Each type of circuit differs based on both its electrical usage and how that usage applies to larger electrical infrastructure. Before Article 726 of the NEC, which officially introduced Class 4, the other three classes included:

Class 1 circuits that meet the following requirements:

  • Class 1 Power-Limited Circuits are supplied from a source that has a rated output of not more than 30 volts and 1000 volt-amperes.
  • Class 1 Remote-Control and Signaling Circuits shall not exceed 600 volts. The power output source shall not be required to be limited.

Class 2 Circuits utilize a step-down transformer rated at 40 volt-amperes or less to deliver a power rating not to exceed 100 volt amperes.

Class 3 Circuits are used if the power demand for circuits over 30V exceeds 1.5VA, but remains under 100VA.

To learn more about Class 2 and 3 circuit limitations, please see the 2023 NEC Chapter 9, tables 11(A) and 11 (B).

How Is Class 4 Power Better?

Class 4 brings a different nuance to the classification ecosystem. It can carry up to 450V but does so in a way that’s as safe to handle and install as Class 2. The result is a system that can run at 100W for more than a mile, or as high as 1,000W over 1,000 feet¹.

This potential length makes Class 4 wiring especially beneficial compared to most contemporary PoE applications, which can only run power reliably for about 100 meters (or 328 feet) without needing additional power supplies along the line. PoE achieves that process via constant monitoring for voltage spikes, drops, and other electrical issues.

Class 4 Power as a Fault-Managed System

Class 4 is the first class of power defined in the NEC that also serves as a fault-managed power system (FMPS). This means it can continually monitor the line for potential faults, while at the same time controlling the current to ensure that energy usage remains as limited as it needs to be.

A FMPS includes a transmitter, which creates the power circuit from the source, along with a stand-alone or integrated receiver, which converts it to the exact power the load device needs to function.

Because of that dynamically limited energy, the risks of electrical shocks or fire are dramatically reduced. Even though Class 4 power is unlike other classes in that it doesn’t limit power, its ability to manage the energy current more specifically means that installation and facilities become drastically safer in the process.

The Benefits of Class 4 Power for Commercial IT Infrastructure

One of the major benefits of Class 4 power is its safety profile. Class 4 power utilizes a power source with a peak voltage output of not more than 450 V DC line to line, or 225 V line to ground. More specifically, Class 4 achieves these benefits through packetized power delivery, digital electricity, and hybrid cabling material.

Packetized Power Delivery

The fault-managed system of Class 4 power is only possible because of the way this system packages individual energy units. The transmitter sends hundreds of these packets every second while monitoring for faults on an ongoing basis. Any type of fault, such as a short circuit or the wrong wire, can cause the transmitter to immediately pause transmission of the Power package.

Because fault detection and prevention are almost immediate, Class 4 power has a substantially reduced risk of shock compared to Class 1, 2, or 3 power systems². The integrated failsafe of Class 4, enabled by packetized power delivery, will always terminate the connection before sending power to a faulted cable or connection.

It’s impossible to overstate the degree to which this innovation can impact the workforce and workplace safety. Power delivery, especially across long distances, becomes safer, reducing the risk of fire and electrical shock.  

Digital Electricity

The transmitter/receiver system of Class 4 power also enables it to support different types of power, including both AC and DC. The electricity gets converted or remains in a DC stream during transmission before the receiver transforms it to whatever the output unit needs. This increases flexibility, especially in complex power infrastructures.

A Hybrid Solution of Copper and Fiber

Part of the power of Class 4 comes from the fact that, unlike most other previous alternatives, this wiring system utilizes neither copper nor fiber exclusively. Instead, it’s made up of both materials.

Hybrid copper/fiber cables are commonly seen in PoE applications where the combination allows for the delivery of both power and data. However, the power portion of PoE is inherently location-limited. This limitation does not apply to hybrid construction used in Class 4 cables.

Though current applications focus on power only without data capabilities, this increases the distance to which the cable can deliver electricity by a factor of 8 compared to ethernet. And because of its flexible materials, hybrid Class 4 cabling can follow the same raised floor Gridd® Adaptive Cabling Distribution® system pathways that ethernet and existing fiber cables already follow.

In Conclusion

Clearly, Class 4 power has the potential to transform the way you think about power delivery, compared to existing PoE options. The rise of smart buildings has made strong electrical and IT infrastructure an absolute must, and Class 4 power is here to deliver.

Despite its increased safety due to its constant monitoring feature, most jurisdictions still require a master electrician to install Class 4 wiring. Nonetheless, this new power class presents a unique opportunity to provide power to devices of all types more safely and efficiently. And, with further innovations surely to come, along with access flooring pathways like Gridd®, that flexibility will only increase in the near and long term.


  1. https://www.descomm.com/articles/National-Electrical-Code-(NEC)-Releases-New-Class-4-Fault-Managed-Power-Category
  2. https://www.belden.com/blogs/smart-building/class-4-power-and-differences-between-circuit-classes

Get real time updates directly on you device, subscribe now.

Leave A Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More