←back to thread

Power over Ethernet (PoE) basics and beyond

(www.edn.com)
257 points voxadam | 1 comments | 16 Oct 25 14:09 UTC | HN request time: 0.802s | source
Show context
skopje ◴[22 Oct 25 00:53 UTC] No.45663732[source]▶
PoE is awesome. My custom home security system is all CCTV PoE with a gstreamer backend running on four-core fanless linux box. Way to go. Complete control. No batteries, no wares spying on me, no personal data getting scraped by big guys. (Cloud connectivity sucks because I have segmented mp4s and jogging through them hurts but I only care for events after they happen, not while they happen.)
replies(6): >>45663770 #>>45664711 #>>45664915 #>>45665099 #>>45665193 #>>45667449 #
dheera ◴[22 Oct 25 05:11 UTC] No.45665099[source]▶
Except when it isn't awesome. There are multiple PoE standards. Passive PoE, active PoE, PoE+, PoE++, PoE+++, 802.11af, 802.11at, 802.foo, blah blah.

If they had just stuck with 12VDC and buildings had 12VDC wall sockets everywhere, everything would have been fantastic.

I also had a PoE HAT for a RPi that smoked it. Never doing PoE again. 48V and 3.3V electronics probably don't belong within 10cm of each other.

replies(7): >>45665150 #>>45665155 #>>45665251 #>>45665484 #>>45665487 #>>45670739 #>>45673430 #
1. throw0101c ◴[22 Oct 25 18:45 UTC] No.45673430[source]▶
> Except when it isn't awesome. There are multiple PoE standards.

There are three: IEEE 802.11af, at, and bt.

af can deliver up to 12W at the powered device (PD), at delivers up to 25 W, and bt either 51W (Type 3) or 71W (Type 4):

* https://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_i...

Any device you purchase should list the IEEE standard it supports and how much power it may draw.