For a very long time, Ubiquiti has been using 24v passive PoE on their legacy airMAX and EdgeMax product lines. This is a proprietary power standard that is not compatible with the 802.3af/at PoE standard used by most other networking equipment.

In this blog post, I'll explain why Ubiquiti uses 24v passive PoE, and why it's still used on some of their products today.

What is 24v passive PoE?

24v passive PoE is a method of delivering power over Ethernet cables. It works by sending 24 volts of DC power over the unused pairs of an Ethernet cable. This is different to the 802.3af/at PoE standard, which uses a negotiation process to determine the power requirements of the device before delivering power.

The term "passive" refers to the fact that there is no negotiation process. The power is simply delivered at 24 volts, regardless of whether the device is compatible with this standard.

Why does Ubiquiti use 24v passive PoE?

Ubiquiti started using 24v passive PoE on their airMAX product line many years ago, before the 802.3af/at PoE standard was widely adopted. At the time, 24v passive PoE was a cost-effective way to deliver power to their devices without the need for a complex negotiation process.

Ubiquiti continued to use 24v passive PoE on their EdgeMax product line, which is designed for more advanced networking use cases. The EdgeMax product line includes routers, switches, and access points that are designed for use in small to medium-sized businesses.

Is 24v passive PoE still used today?

Yes, 24v passive PoE is still used on some of Ubiquiti's products today. However, Ubiquiti has been transitioning to the 802.3af/at PoE standard on their newer products, such as the UniFi and UISP product lines.

If you're using a Ubiquiti product that requires 24v passive PoE, you'll need to use a compatible PoE injector or switch. Ubiquiti sells a range of 24v passive PoE injectors and switches that are compatible with their products.

It's also worth noting that some third-party PoE injectors and switches are compatible with 24v passive PoE, so you may be able to find a compatible device from another manufacturer.