Welcome to Networking — Episode 04
PoE Power Levels and Heat
August 14, 2026 · 5:25
Prefer YouTube? Watch this episode on the channel — comments and questions live there.
About this episode
On a full length Type 4 run, ninety watts leave the switch and about seventy one arrive at the device. The missing nineteen watts do not disappear. They become heat in the cable along the whole run. Now multiply that by every powered run in the same bundle.
This is the short one, and it is the episode that changes what you order. PoE levels from 802.3af through 802.3bt, where the heat comes from, why the center of a bundle is the worst place in it, and why an uninsulated ceiling in August is part of the calculation.
The design response is small, and it is cheap, as long as you make it before installation rather than after.
Chapters
The same chapters as on YouTube, so you can find your place in either player.
- 0:00 Heat in a network cable
- 0:30 What PoE delivers now
- 0:52 The four power levels, and the missing watts
- 1:41 Why bundles warm at the center
- 1:59 An uninsulated ceiling in August
- 2:14 Heat, resistance, and more heat
- 2:48 The bundle guidance
- 3:22 Planning for PoE from day one
- 3:49 The rack side corollary
- 4:09 What this asks of you
- 5:00 Outro