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48V network switches and Ubiquiti 802.3AF adapter

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WU2S's picture
48V network switches and Ubiquiti 802.3AF adapter
For those considering long Ethernet runs between a PoE injector or switch and the Ubiquiti node, here is another option worth considering. On long runs, it is more efficient to power at a higher voltage, so you can use a Switch such as the Netgear GS108PEv3 or the Toughswitch TS-9-Pro at 48V. The key to success is to use a Ubiquiti Instant 802.3AF outdoor 48V PoE adapter at the node end of the cable. I recently tried this adapter with both types of switches and it works well. The Netgear switch is auto-sensing (true 802.3af) and the Toughswitch is passive PoE (not auto-sensing).

Randy WU2S
These devices can certainly

These devices can certainly be useful if integrating into an existing power distribution switch.

Though I want to caution that I believe you loose the ability to remotely trigger the remote reset with these devices.

While hopefully that will not be necessary to utilize it may be better to use passive 24v instead so that you can remotely reset the device from the ground should it ever be necessary (forgotten password for example.)

It is good to have options however and encourage each deployment to decide what's best for their own needs. I can think of many situations where these can be useful and that loss of reset is not significant.

k1ky's picture
Reset Options
Thank you for mentioning the reset issue.  A work-around fix would be to insert a UBNT power injector in line when the reset is needed.  I have indeed benefitted from the "remote reset"  when I accidentally installed a unit 140 feet on a tower that had the wrong programming installed.  I had the unit labeled, but I had not installed the AREDN firmware AND it was purchased used and had "other" programming with a foreign password on it.  The ability to perform a remote reset saved our bacon on that installation as I was able to re-flash the unit after it had been reset to factory fresh.
The 802.3af injector would

The 802.3af injector would have to be at ground level I belive (I don't have one to confirm) as I can't see it passing passive power and reset through the 802.3af adapter.

there is a distance where the 16v out of these adapters wouldn't be viable. 

They are designed for 48v (very low loss) to go up the feed and convert to 16v at the device (this is a nice high voltage above the minimum but below the chip frying maximum) 

I believe the 16v POE's use to be recommended to 100feet and then 24v POE's were recommended by WIFI wisps. This would apply to the 802.3af converters as well.

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