Can 28 AWG Patch Cords Support PoE?
Over the last few years, extra space inside rack wire managers is harder to come by. The reason? Many patch cords are taking up lots of room—especially with the increase in Category 6A cable use, which is a thicker cable (although it has decreased in diameter in recent years).
As a result, requests for patch cords with a smaller cross-sectional size (smaller diameter) have increased. Skinnier patch cords (like 28 AWG patch cords) help save space. If you've ever held one, you know how small they are in comparison to other options (they feel almost as thin as your headphone cord).
Compared to 24 AWG patch cords, 28 AWG patch cords are more than 50% smaller in diameter. They help reduce pathway congestion, generate room for equipment and make high-density, bulk patching easier.
Originally designed for use in data centers, 28 AWG patch cords are now being used for everyday patch cords because of the space savings they offer. As simple as it sounds to just use a 28 AWG patch cord instead of a 24 AWG patch cord to save space, making that switch can cause complications when Power over Ethernet (PoE) is involved.
Why Cable Diameter Matters in PoE Applications
With all types of devices now connecting to networks via PoE cable, from wireless access points to surveillance cameras, a new question about 28 AWG patch cords started to arise: Can they be used in PoE applications?
There are a few important factors to keep in mind. First, a thinner cable also means a smaller conductor (the cable component that allows the free flow of electric current).
Sending power through a cable via PoE using a smaller conductor means that more heat is generated – and extra heat must be compensated for.
Because of their smaller size, cables are also closer together when they’re in a bundle, making it even easier for heat to build up. Too much heat negatively impacts cable performance and can cause a cable’s temperature to exceed its jacket rating.
Can 28 AWG Patch Cords Be Used to Deliver Power?
Before February 2019, the short answer to "Can 28 AWG patch cords be used in PoE applications?" was "no." Today, however, the answer is "yes"! 28 AWG patch cords can now be used to support power delivery.
Per TSB-184-A-1, an addendum to TSB-184-A: 28 AWG in bundles of up to 12 can be used for PoE applications up to 30W.
In PoE applications using between 30W and 60W of power, spacing of 1.5 inches between bundles of 12 cables is recommended. (Most of the PoE use cases we've seen so far involve power levels below 30W.) Anything above 60W requires authorization from the authority having jurisdiction because 28 AWG isn't mentioned in the National Electrical Code at 60W.
If your project calls for a larger bundle size or power levels that are higher than 30W, Belden can offer guidance on how to safely and effectively approach these situations. Just send us a note to get started!
Über den Autor
Greg Funk began his career in 1984 as a distributed computer network analyst. Serving Belden for more than two decades, Greg was one of Belden's data center experts and a recognized speaker at industry seminars and events. He fulfilled a variety of functions and was a field application engineer providing network engineering sales support in his region.