Using Unifi POE injector (bundled with the AP) in a POE switch...

[MrWu]

Hi;

 

A wierd question;

 

I know that UniFi's AP isn't compatible with native 48V POE switches, but for testing I'm putting some UniFi APs in a room near an exisiting POE Test switch (I haven't got enough of the UniFi's instant POE injectors for that room)

 

Has anyone tried plugging an UniFi AP eith the external power brick injector (that came standard with the Unifi) into a POE 48V switch..would it have harmful effects?

 

Cheers

[Domino]

If you disable POE on the port its connected to you shouldn't have an issue...

[m25man]

The 802.af standard tests the connected device before delivering 48v, if your load (such as the data port on a Unifi brick) doesn't ask for 48v it will never get it.

In theory your quite safe to connect anything to your switch it will only supply 48v if the device is compatible.

 

Beware of the Unifi instant AF adapters, they overheat and self destruct despite this being well known there are still large quantities of defective units floating around and no easy way of identifying the bad ones from the good ones.

Make sure you have spares on standby.

[MrWu]

Thanks.

 

Just tried it today with the Netgear GS724TPS switch, indeed M25man is correct on the web admin console does not register output voltages on the POE ports where the injector is plugged into.

 

The 9 APs have been running since lunchtime and so far all is well.

[DarrenG]

Aye as mentioned if the switch is 802.3af then you will be fine, no need to disable PoE on the port. That said I would tend to do it anyway but then I am overly cautious!

[DarrenG]

M25 is that the same for both the indoor and outdoor instants? I've not heard about this before so handy to know.

[m25man]

M25 is that the same for both the indoor and outdoor instants? I've not heard about this before so handy to know.

I have only seen it on the indoor units, Q14 gets so hot it desolders itself from the PCB.

The outdoor unit has a larger casing and moulded fly lead whilst I have not seen these suffer the same demise they are seldom used internally due to the size and fly lead.

A modified version of the internal has supposedly been released but I have yet to find one in the wild, everyone of the internals I have had/seen has suffered the same fate.

 

The Unifi instants seem incapable of switching an 802.af supply to the correct Class loading, so the .af input negotiates the switch to output an 802.af output and then just takes the max load offered by the switch only to shunt it down to 18v.

The result is one very hot regulator tranny.

 

The first you know of an issue is when the controller starts to log regular disconnects of the AP. The defective Instant AF adapters develop a brown spot of molten plastic on the label side and will burn your fingers if touched!

I have removed all of the instant AF adapters from service now and replaced them with either the regular passive units or bespoke 24v midspans.

 

I have no doubt that 30 feet up a mast the externals will run cool enough not to experience a problem but I'm a bit worried about burying the internals under 6" of fibreglass insulation sandwiched to a compressed cardboard ceiling tile!

[DarrenG]

Thanks M25Man, very useful to know