Hello anyone…
I have recently purchased a powerbox. I am supplying power to it via PoE. I have three SXT units attached to it. I cannot get the SXT units to stay powered on. In the Interface/PoE window I can see the unit power up with 1amp and 23.3 volts it then very quickly cycles to “short circuit”. It does this for 2 of the 3 units. One unit is not getting power at all. I am using shield Cat6 cable. Anyone with a clue as to what is happing your guidance would be greatly appreciated.
/interface ethernet poe settings
set ether1-poe-in-long-cable=yes
That should be changed to default I think.
I am going to head back up there on Saturday and will post on how that setting worked. Thank you for taking the time to help! 
This helped us out tons and I am greatly appreciative of your post. We had lab tested 3 different units and once up on a small tower all had failed. We were baffled and about to go back to ubiquiti edgepoints. So glad we read this before we did it 100% solved our issue. I agree this should be a default setting. Cheers!!! 