Heat Rise In Power Over Ethernet (PoE) Applications: Why Cable Choice Matters

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September 16, 2016 at 5:25 pm  •  Posted in Data Communications, Safety  •  0 Comments

From wireless access points to HDBaseT technology, Power over Ethernet (PoE) has taken the world by storm. Highly sophisticated equipment contributes to an increasingly convenient and connected world, but it also demands more power.

When paired with specialized equipment, Ethernet-powered IP cameras can easily suck up 60 watts. HDBaseT technology, an even greater power hog, transmits up to 100 watts of power through a single LAN cable. And that’s just the tip of the iceberg.

In applications approaching 100 watts or greater, temperature rise is a concern. And minimally compliant Category 5e cables can’t always handle the heat.

Article Contents:
In high-wattage applications, cable choice matters. Contractors need to think about what they’ll be powering today, and in three, five, or 10 years down the road. When it comes to cabling, things are about to heat up. Here’s what contractors need to know about cable choice in Power over Ethernet applications.

The Limitations Of Cat 5e Cables

In high-powered PoE applications, especially in long runs, contractors need cables that can go up to a certain wattage without exceeding the temperature rating.

When you power up a Cat 5e cable to 100 watts of power or greater, the temperature rise can be significant—especially in tough environments like conduits or raceways under other cables. In high-power PoE applications, traditional Category 5e cables just don’t cut it.

To illustrate this concept, General Cable powered a traditional Cat 5e cable, a 22-gauge Category 6, and a GenSPEED 10 MTP Category 6A cable up to 100 watts. Here’s what happened at different levels of heat generation:

Changing Code & Requirements

Limited Power (LP) Certification For PoE

To measure how much power a cable can handle, UL recently came up with a new listing criteria for PoE performance.

To address the concern of heat rise, UL rolled out a Limited Power (LP) Certification to help installers choose the right cables for Power over Ethernet applications. Cables that bear the “-LP” designation have been tested and proven to perform in tough installation scenarios without going beyond the temperature rating of the cable.

“UL’s Limited Power (LP) Certification for PoE gives the contractor, the installer, and the end user confidence. No matter what environment the cable is installed in—whether it’s open air, cable tray, a three-cable bundle or a 200-cable bundle—they’re not going to have to worry about performance issues related to heat rise in PoE applications,” said Matt Gentile, Product Manager at General Cable.

“General Cable is the first company to obtain LP listings and bring UL LP-listed cables to market, and we’re very proud of that,” he added.

National Electrical Code

Limited Power (LP) Certification underscores the importance of choosing the right cable for PoE applications. So much so that National Electrical Code now includes LP cables as an aid to certify performance in high-power applications.

In the recently revised 2017 National Electrical Code, LP cables are represented as an alternative to using complex ampacity tables.

“I’m so pleased that LP-listed cables are included in the 2017 National Electrical Code. For the first time, the NEC is addressing how much power to put over a category cable,” Matt told Graybar.

“Up until now, you could basically put unlimited power through a category cable, which is a big safety risk. The LP listing simplifies the design process, improves safety, and eliminates guesswork. This is a positive step for customer safety and the industry as a whole.”

Cables That Keep Their Cool: GenSPEED® LP-Listed Cables From General Cable

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When the watts start climbing, will that Cat 5e cable stack up? Better not chance it. General Cable’s LP-listed cables are the ideal solution for Power over Ethernet applications because they’re certified by UL to withstand 100 watts and beyond.

When your application calls for industry-leading data and power capabilities, GenSPEED 10 MTP with EfficienC Max Technology delivers. With an LP listing of 0.7 amps, these Category 6A cables can power up to 140 watts without getting hot under the collar. It’s the ideal solution for power-hungry PoE applications.

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Sources & Credits
CISCO: The Internet of Things—How the Next Evolution of the Internet Is Changing Everything
UL: Limited Power (LP) Certification for Power-over-Ethernet applications
National Fire Protection Association: NFPA 70: National Electrical Code (NEC) Handbook, 2017 Edition

 

Todd Reed, National Market ManagerAbout The Author
Todd Reed, National Market Manager

As National Market Manager at Graybar, Todd’s goal is to find the best products and solutions to help contractors work more efficiently, stay safe on the job, and win more productive and profitable business.

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