PoE, Power over Ethernet – What it means for Access Control Systems

In the computer industry, acronyms are standard fare.  One acronym in particular, PoE, or power over ethernet, is already having a huge impact on the physical security side of building management.

Power over ethernet is regulated by IEEE standards 802.3af or 802.3at Type 1 and by 802.3at Type 2 or PoE+.  This specification allows for a maximum power consumption at the device of 12.95W (350mA) for standard or 25.5W (600mA) for PoE+ along with transferring data over a Cat5 or Cat6 cable.  

What this allows, the ability to run a single, cost-effective cable to the opening to power and communicate with your system controller, electric lock, credential reader, request to exit, and door position switch. There are even manufacturers making PoE electric latch retraction retrofit kits for exit devices.

Additionally, the side benefit of PoE, is the reduced power consumption of the system as a whole.  I did a recent study for a building that is going for Net Zero energy consumption credits, that under typical system design practices, would consume around 26A of 110V line power.  By switching to a PoE based system and modifying the hardware slightly, I was able to get the system down to about 8A of 110V line power or 31% of the original requirements.

What are the downsides besides limited power at the device?  The IEEE standard only allows for a maximum of 100 meter cable length from the switch to the device.  Most modern buildings are designed with data cabling in mind, but this will require pre planning of your installation with cable lengths.  Another is the delicate nature of Cat5 and Cat6 cabling when installing.  The installers need to be trained on proper cable pulling techniques to minimize cable strain during installation.

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