Impact of 2017 NEC on Remote Powering
Clay Kobernick, supplier relations manager at Anixter, discusses recent changes to NFPA 70, the National Electrical Code (NEC), as well as changes to remote powering standards such as IEEE 802.3bt, and considerations to keep in mind if you are deploying a new remote powering system in a building.
Read our TECHbrief on remote powering methods to learn more about this topic.
Hi, I’m Clay Kobernick. I’d like to share some recent changes to NFPA 70, the National Electrical Code, and talk about what these changes mean if you’re looking to deploy a new remote powering system in a building.
The 2017 edition of the National Electrical Code addresses the delivery of low-watt power over a communications structured cabling system. Specifically, it sets a threshold of 60 watts for power supplied over communications cable as defined in Article 800 of the code. Above 60 watts, it points to a new ampacity table for traditional four-pair LAN cabling. This table also provides bundle size requirements for cables used in remote powering applications.
These changes all have to do with heat generation of cable bundles within the structured cabling system, which is important because remote powering standards, such as IEEE 802.3 Power-over-Ethernet and HDBaseT standards, are also changing.
For example, the newest proposed IEEE standard for PoE known as the 802.3bt significantly increases the power that can be delivered to a device. The 2009 IEEE 802.3at standard of about 25 watts allowed for enough wattage to power access points, cameras and some types of lighting. The proposed IEEE 802.3bt standard allows for upwards of 70 watts to be delivered to the end device, which will enable a number of new applications in commercial buildings, factory floor environments, and the transportation sector. However, the various standards committees within the industry are still debating whether higher power levels can be supported on communications cabling without compromising performance and safety.
From a safety standpoint, end users and installers need to be aware of the heat generation that comes with more power being delivered over communications cables. The 2017 National Electrical Code addresses cable heating and the four main heat dissipation factors: the wire gauge, the cable construction, the materials and the installation.
If you’re looking to deploy a remote powering system such as PoE or another Class 2 system in a building, do your research and talk to experts to understand how the 2017 National Electrical Code applies to your power scheme. We also recommend that you work with the authority having jurisdiction from the beginning of the process to help ensure compliance.
To learn more, talk to your Anixter representative and download our TECH brief on remote powering.