--- title: "Why your cameras reboot at night: PoE budgets explained" description: The most common fault in camera systems installed by someone else is not the cameras. It is the switch that powers them. date: 2026-08-18 updated: 2026-08-18 tags: [cameras, networking, troubleshooting] url: "https://relaypoint.ca/blog/poe-budgets-explained" author: RelayPoint Technologies --- Power over Ethernet is simple in principle: the network switch sends power down the same cable that carries the video. Every switch has a total power budget, and every camera draws a share of it. When the cameras collectively ask for more than the switch can give, the switch starts shedding ports, usually at night when infrared illuminators kick in and draw the most current. ## How to check yours - Find the switch model and look up its **PoE budget** in watts. - Add up the *maximum* draw of every camera, not the typical draw. Infrared and pan-tilt cameras spike. - Leave 20 percent headroom. :::tip Rule of thumb Eight 4K cameras with IR want roughly 100 W at night. A "PoE" switch with a 65 W budget will power five of them. ::: If the total is over, the fix is usually a bigger switch or a second one, not new cameras. We check this on every system we install and on every system we are asked to look at.
**What you'll notice** Cameras dropping offline after dark, NVR showing "video loss", devices rebooting in a loop. **What it isn't** Bad cameras, bad cable (usually), or the NVR. Check power first.