What are the Differences Between Passive and Active PoE?

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If your device uses 802.3af or 802.3at it is considered to use active POE.  What that means is that the PoE device (Camera/Radio/Telephone/etc.) will check the power coming in and if it doesn’t meet the device requirements it won’t power up.  802.3af/at does a handshake between the sending and receiving POE devices and won’t power up if the receiving device doesn’t provide the proper acknowledgment. 802.3 af/at PoE voltage will always be 44 to 57 volts DC.

-Passive POE usually refers to any device using POE to power that is not 802.3af/at.

-This includes things like cameras and radio antennas that run on 18-48V DC PoE.

-Passive POE does not do a handshake, so it is extremely important to know what POE voltage your device requires before plugging in the CAT5 cable and powering it up.

NOTE: If you connect the wrong voltage, you can easily burn up your device.