Home Network Geekiness (Power over Ethernet)

About two and one-half years ago, I did some house wiring to facilitate home networking in our then recently purchased house built before the age of the internet. That involved using the attic as a central location due to the ease of running network cable for some ports and wireless access points. It also required that I get creative about surge protection and operating temperatures due to attic heat. Normally I do uninterruptible power supplies on all critical equipment. However for the attic temperatures, that equipment is a bit pricey to justify, so I left the equipment up there as surge protected only.

All normal consumer equipment maxes out at 40 degrees Celsius or 104 degrees Fahrenheit for operating temperatures. Things double or triple in price when you try to get 50C/122F or above equipment. For example, I can only find one unmanaged 5-port switch that handles 50C/122F. Fortunately, I’ve found a relatively inexpensive option that gives me uninterruptible networking in the attic: A Power over Ethernet 5-port gigabit switch that operates at 50C/122F.

Power over Ethernet (PoE) is a networking feature defined by the IEEE 802.3af and 802.3at standards. PoE lets Ethernet cables supply power to network devices over the existing data connection.
A 802.3at injector
PoE-capable devices can be power sourcing equipment (PSE), powered devices (PDs), or sometimes both. The device that transmits power is a PSE, while the device that is powered is a PD. Most PSEs are either network switches or PoE injectors intended for use with non-PoE switches.

The Netgear GS105PE is both a PD and a PSE, however it must be powered by 802.3af or 802.3at.  There is no power supply for this switch.  802.3at is known as PoE+.  The major difference between 802.3af (PoE) and 802.3at (PoE+) is that PoE+ PSEs can provide almost twice as much power over a single Ethernet cable.

Supplying the GS105PE with PoE+ gets you 19 watts of power budget for use on ports 1 and 2.  That is enough to power one PoE access point and another low power device with no worry about outlets, outages, nor spikes when I plug an 802.3at injector in to a UPS in air-conditioned living space!

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