Will high-power PoE burn up a Cat 5e cable?

Back in the days when Ethernet cable only carried network traffic, the twisted pairs in the cable only had to handle a few hundred milliwatts at most. New Power-over-Ethernet specs now distribute up to 90 watts-worth of DC to loads through these same twisted pairs. If you wonder how ordinary network cable behaves when it handles this much power, take a look at the results of our informal tests.
www.powerelectronictips.com/h...

[@grumpysandwich]

haha that cable started smoking at the end and the look on the presenter's faces :D

[@wisteela]

I thought that was from the load resister.

[@Super_Lizard]

Awesome, thank you so much for doing this test. I have wondered about this for a while. I agree with you if it doesn't show up in a couple hours your safe.

[@redderek]

When working on the IEEE 802.3at standard board for PoE to 90W, we looked at heat dissipation. Not only for single cable, but for cable bundle as well. This was also looked at a length of 100m cable. No issues were found. Using CAT5E is not an issue for high power PoE. Key is to keep current under 2A. There is a voltage drop over the 100m cable and thus the end voltage, at 2A does drop around 15V and thus lower power at the far end of a 100m cable as compared to using a length much shorter.
The 802.3at standard committee did run this type of test and much more by running bundles and the 100m length. This is a nice video, but barely touches the work that the standard committed performed while working on the 802.3at standard. The team looked at power loss, temperature rise, data interference (at maximum data rate), and many other aspects of the CAT5e cable. Rest assured that 803.3at would not have passed if those on the committee did not feel it was sufficient. Members included Cisco and other companies involved in both data transmissions and power distribution.

[@yigitkaygusuz4502]

hi, 26awg cat5e can handle 12v 2a with poe?

[@redderek]

@@yigitkaygusuz4502 yes. It is the current capability, not voltage. You can do 20V as well. High power POE is operating at 48V

[@johnjacobjinglehimerschmid3555]

Do you know if there's a calculator out there that you can put in various data points like length of run, required A at the end of run and or req voltage at end of run and it would calculate max length? input voltage, input current data?

[@redderek]

@@johnjacobjinglehimerschmid3555 yes. I wrote one regarding wire size and current. It calculates voltage drop. Pretty easy to make in a spreadsheet. There's are tables that provide resistance per length based on wire size. Do not forget to double the drop because of the return length.

[@drbiosgmailacc5191]

@redderek Hi, will Cat5e CCA (not solid copper) be able to handle 48v 2A?