Whenever possible, I opt for PoE. It’s a damn shame it’s limited to a niche userbase given its myriad advantages.

Do you buy Ethernet cables of different colors and say "Yellow is reserved for PoE, all yellow cables should be assumed to have power on them"? Or do you slap a "48V" label on both ends of the cables you're going to use for PoE and the label is what warns you that this cable should only go into the PoE receiver, and not into an unpowered device? Or do you just not label your PoE cables any differently, and trust that the injector will never malfunction at the same time that you plug the PoE cable into the wrong device?

> The above figure shows a PoE injector with auto negotiation, a safety and compatibility feature that ensures power is delivered only when the connected device can accept it. Before supplying power, the injector initiates a handshake with the PD to detect its PoE capability and determine the appropriate power level.

If PoE requires negotiation, and the device requires PoE for power.. how does it perform the handshake without being powered/booted first?

I designed and built my first POE system in 2004, at my own house as a dogfooding POC, and that system stills works to this day. Since that time I have built and installed many more without issue that continue to move along doing what they were intended to do, protect life and property via recording activity privately. My own home footage has been called upon several times by law enforcement and was critical in convicting at least one home break in crew.

The benefit of install is simple to comprehend for those with significant experience in the electrical field, run one small wire for data and power and ensure the POE supply is on a battery - done. Additionally I add those using WiFi for security are laughed at daily as losses pile up, web search MLB player home break-ins, as running a hardline cannot be jammed but many foolishly put all their assets solely behind WiFi security. Also these surveillance systems require no external cloud by design so no one is watching remotely, unlike the Fed and State viewing your Ring cameras for years and now which recently partnered with Flocker. No one cares more about you than you so if someone is selling you security ask yourself what it is you are actually paying for.

In closing, as we move into a new era of technological efficiency forced by rising energy prices and costly electrician labor hours, one is going to witness an uptake of POE adoption in more and more nontraditional places. It is already happening and its moment will come as more recognize the cost benefit to this greatly simplified power delivery method with integrated battery backup.

What you cannot see matters most!

- PoE endpoints should have isolation barriers, factor this into cost and size estimates

- Don't skimp on TVS

- ideal diode full bridge rectifiers are really cool and you should use them (in more power entries than just PoE)

I have it to run a couple of MikroTik devices in awkward places and not having to run wall warts and flimsy DC cables around the place is very handy.

My next switch upgrade will be a proper PoE+ one, but it’s not justified yet.

It feels magical to have the PoE injector tucked in a cupboard with the optical network terminal, and outside Narnia, the router has only one cable going to it. Also, the Ubiquiti PoE injectors are particularly satisfying. Powered by standard AC cables, and a nice simple design. Now that I've experienced this magic, I'm not going back!

However, as much as I love the hAP ac², it only accepts passive PoE. I don't love passive PoE - it scares me! Unfortunately, it seems like most (all?) Mikrotik routers only accept passive PoE.

Does anyone know of a good alternative when it comes time to replace my router? I would have liked it to be Ubiquiti, but I don't usually read positive things about them around here.

For example, my Chromecast gets power and wired ethernet through its USB C port. (I have an official Chromecast power brick that I plug an ethernet port into.)

I have a Ring home security system. I would like to get an offline home CCTV that only records when the alarm is set (either in Home or Away).

A quick internet search does not show an API. I'm not sure Ring has a device that I could wire a relay (if that's the right thing) to.

2. How does PoE compare to Powerline Networking?

PoE (Power over Ethernet) sends both DC power and data through the same twisted-pair Ethernet cable, allowing devices like IP cameras, wireless access points, and VoIP phones to run without separate power lines. The power is delivered by Power Sourcing Equipment (PSE) — either an endspan (built-in PoE switch) or a midspan (PoE injector placed between a non-PoE switch and the device). The powered device (PD) negotiates power via detection and classification before voltage is applied, preventing damage to non-PoE gear. IEEE 802.3af (Type 1) provides up to 15.4 W at the source, 802.3at/PoE+ (Type 2) up to 25.5 W delivered, and 802.3bt (Type 3/4) extends that to roughly 60–90 W using all four wire pairs. Engineers need to understand not just wiring, but also cable category limits, pair usage, power losses over distance, and heat dissipation — especially at higher power levels. Modern PoE designs must consider standards compliance, thermal management, and efficiency, as power density rises with new generations of PoE technology.