NFPA Members and AHJs can use the Technical Questions tab to post queries on NEC document information webpage.

Author(s): Derek Vigstol. Published on January 2, 2018.

In Compliance | NFPA 70

How the NEC addresses fire hazards associated with Power Over Ethernet equipment


If you’d told me 15 years ago that we would soon have lighting that could learn a building owner’s habits to reach optimal efficiency, I’m not sure I would’ve believed it. If you’d described an emerging technology that enabled lighting to sense varying conditions within a building and seamlessly integrate with the building automation system to return everything to the optimal use of energy and the optimal conditions for occupants, I probably would’ve reminded you of the flying cars we predicted in the 1950s.

But I would have been dead wrong. This technology isn’t merely emerging—it’s here in a big way, and it’s evolving daily in the form of Power over Ethernet, or PoE.

Power over Ethernet equipment utilizes communications cables to both supply power and transmit data, allowing the built environment to become “smart” through what has come to be known as the Internet of Things. PoE isn’t exactly new technology—it’s been used for years for equipment like telephones and security cameras. However, electrical equipment has become much more energy efficient, and there is growing pressure to build systems networks within buildings that owners or facility managers can use to keep the buildings running more efficiently. As a result, PoE technology is leaving the confines of the communication world and expanding into areas that until recently seemed as far off as flying cars.

Integrating these systems into buildings, particularly existing buildings, and identifying the related hazards can present key challenges for PoE stakeholders. But NFPA 70®, National Electrical Code® (NEC®), can help. Essentially, the NEC is a big book of rules that protects us from shock, arc flash, and fires. Since PoE is able to operate at low voltages, sometimes within the 12- to 24-volt range, shock and arc flash tend to be less of a concern when approaching requirements within the NEC. This isn’t to say that there’s no possibility of shock, but it is less likely to be an issue at such low voltage.

There are two important points to consider when assessing the fire risks associated with the installation of PoE equipment: the threat of the equipment starting a fire, and the threat it poses during a fire. With this in mind, it’s easier to understand why the related NEC requirements have developed the way they have. PoE cables are often bundled in a manner similar to other communications cables, and as more power is introduced on these cables, heat dissipation can become an issue. The 2017 NEC includes limitations on how much power PoE cables can carry before they need to be treated as Class 2 or 3 circuits. Article 840 contains a new section in Part VI that requires section 725.144 to be followed when the power supplied to equipment on communications cable exceeds 60W. This requires that PoE cables follow Parts I and III of Article 725 and that they are installed in the same manner as any other Class 2 or 3 circuit. Power above 60W also calls for adherence to the requirements of 300.11 or the general NEC requirement for ensuring that cables and raceways are secured in place and properly supported, potentially limiting PoE cable over 60W from being installed in large bundles where proper heat dissipation can be an issue.

The Fire Protection Research Foundation has also joined the discussion and has assembled a team that will work to find answers and make recommendations on how to appropriately regulate this growing industry. Rules and regulations should effectively minimize the hazards but also need to allow innovation to drive us into the future. Answering questions about electrical shock hazards, fire ignition issues, flame spread characteristics, what the addition to a building’s fuel load might look like, and what products of combustion might be added will help us effectively protect the world from potential hazards, and be done in a way that allows this technology to grow.

Who knows—maybe someday soon PoE will make possible my dream of a refrigerator that learns my cooking habits and automates my grocery buying so I never have to come up with a list or brave another grocery store line an hour before the big game. Hey, a guy can hope.

DEREK VIGSTOL is NFPA technical lead of Electrical Tech Services.