More Power to You

IEEE802.3bt provides more versatility and cost efficiency

• By Ronnie Pennington
• Dec 01, 2019

Many of you may remember the show “Home Improvement” from the 1990s with Tim the Tool Man, who was played by comedian Tim Allen. In most episodes, Tim pursued his continual quest to supplement everyday appliances with “more power” often with reckless abandonment, but always in a humorous and almost slapstick manner. Today’s professional security industry seems to have adopted the “more power” mantra by taking a much more pragmatic approach, as edge devices continue to become more complex and are pushed to new physical distances to extend the reach of security, access and surveillance networks. The adoption of the new IEEE802.3bt PoE standard clearly supports this on-going trend.

Now often referred to as 4PPoE or 4-Pair PoE, IEEE802.3bt provides up to 90W over all four pairs of wire in a structured cable to evenly distribute power. This allows IEEE802.3bt to be deployed for two distinct types of installation applications. The first is to power new PoE products with bigger features, faster motors and more capabilities. The second, and perhaps more significant, is to provide 12VDC and 24VDC to non-PoE compatible devices, such as maglocks or strikes, using new PoE-driven power supply solutions.

802.3BT Midspan/Injectors Pave the Way

We are already starting to see more manufacturers explore the use of 802.3bt beyond LED lighting for a variety of access and surveillance devices.

In preparation for these next generation products, new PoE injectors, such as Altronix NetWay 802.3BT (4PPoE) Series Managed Midspans, are already available. Capable of delivering up to 90W per port (480W total on 4 port models), these new midspans provide power for the latest power-hungry illuminators and multi-sensor PTZ cameras that conform to the new IEEE standard.

New PoE Driven Power Supplies

Using IEEE802.3bt injectors/midspans to provide power to PoEdriven power supplies is a game changer as it significantly reduces the overall cost to deploy access control and myriad security devices by eliminating the need for a licensed electrician.

One immediate mainstream application is deploying electrified locks and strikes. New PoE-driven power supplies like the Tango1B from Altronix allows for a PoE input of 15.4W, 30W, or the new 4PPoE 90W and converts it to a useable 75W of available power. While there are PoE adapters that convert to 12VDC or 24VDC, the available power is limited. With 75W available, an installer can have the ability to power an entire access control system, including the panels, locks, readers, request to exits devices and charging batteries all with a single Cat 6 cable.

For example, based on calculations using Mercury controllers, 75W can potentially power a conventional eight-door access control system. If the 75W capacity is too close for comfort and you prefer to have reserve power built into the system, you can reduce power consumption by installing a midspan injector or PoE switch that has battery backup.

This eliminates the need for battery backup on the PoE-driven power supply and alleviates 10W. If that is not the route you want to take, limit the PoE-driven power supply to 4-6 doors, and use two PoE-driven power supplies with 12VDC devices on one power supply and the 24VDC devices on the other. The cost to add the second PoE-driven power supply will certainly be much less than the cost of an electrician to provide power at the installation location.

This method of powering an access control system will eliminate the need to schedule a certified electrician to wire the power supply, and run a dedicated conduit to the electrical panel. It also makes installation and system maintenance easier. The category cable used for power can run in the same cable trays and paths as other network cabling as well as the access control cable.

When servicing the system, there would be no high voltage inside the enclosure making it safe to unplug the Ethernet cable from the PoE driven power supply. Once the cable is plugged back in, the handshake is performed with the midspan/injector and 802.3bt PoE is sent back to power the system.

The new IEEE802.3bt 4PPoE standard provides a host of benefits and allows for a new generation of high-powered security and surveillance devices to be deployed with extreme efficiency at the edge. More power to all of the system designers, integrators and endusers out there.

This article originally appeared in the November/December 2019 issue of Security Today.