PoE Offers Benefits For Security Gear

• By Steven Titch
• Nov 21, 2008

As organizations look to increase the number of cameras and access control terminals within their security infrastructure, power-over-Ethernet (PoE) switches and midspans are getting more and more attention as a cost-effective way to extend power to remote devices.

The emergence of switches and midspans that conform to the latest PoE standard, 802.3at, has only heightened interest further. The new standard, which boosts POE power delivery down a Category 5 Ethernet cable to about 25.5 watts, provides the capacity that can be used to support the requirements of most cameras and access devices.

The result is that a number of PoE equipment makers, including Microsemi Corp., D-Link, Lantronix, PCSC and GarrettCom, brands long familiar in the telecom and networking sector, see new growth for PoE applications in security.

“The main applications for PoE have been phones and wireless access points,” says Daniel Feldman, director of marketing for telecom products at Microsemi. “Increasingly it’s been cameras and now access control devices.”

Microsemi, founded in 1960, is known largely as a manufacturer of high-reliability semiconductors for the defense and aerospace industry. The Irvine, Calif.-based company acquired its line of PoE switches and midspans with its purchase of Israel’s PowerDsine for $245 million in 2006. Microsemi is now a major OEM supplier of PoE equipment to a number of leading IP camera vendors, counting players such as Axis Communications as customers.

Using PoE, a single Category 5 cable provides both data and power eliminating the need for a separate wire to power the end devices, Feldman says. Security cameras and access control terminals, such as card readers and door locks, can be installed without the additional expense of contracting an electrician to install AC outlets where the equipment is deployed. This, of course, gives users more options as to the location of cameras and access devices.

A PoE switch is essentially a box integrated or collocated with an Ethernet switch. A PoE midspan, as the name suggests, resides between the Ethernet switch and the terminal equipment, delivering data, along with power, from switch to powered devices. PoE relies on four of the eight wires in Cat 5 or higher cable to transmit a DC current of 350 milliamps at 48 volts over a length of 300 feet. Electric power is acquired from a typical AC source, converted and transmitted. Before relying electricity to a device, a switch or midspan will determine if the end device accepts PoE, preventing any chance of an electric burnout. “You only deliver power if the device can receive power.” Feldman says.

The new P 802.3at standard, also known as PoE Plus, doubles the power from the older 802.3af standard. The at standard’s 25-watt power budget means more equipment can be placed on one connection. A card reader typically requires 3 watts, a door lock 6 watts, and camera 13 to 25 watts (see “New Standard Boosts PoE,” Network-Centric Security, October 2008).

When considering a PoE solution, users must take the overall power budget into account. Additional HVAC may be needed to dissipate heat from the power equipment. Users also must consider the additional amount of UPS backup required, Feldman says.

For switches, PoE adds between $10 and $50 per port, Feldman says. For midspans, the variation is between $30 and $50 he adds. This cost can be balanced against the need to extend power to the desired location, and the additional utility the user can derive by adding PoE to an existing Ethernet switch. “In 90 percent of the cases, the midspan is cheaper,” he adds.