Hi Mikrotik. Would like to use RB1100Dx4 in a telecoms rack with supplied -48V telecoms power.
In the past we needed to isolate CCR1009’s for instance as they were standard negative ground.
Is it possible to provide more info about grounding compatibility on RB1100Dx4’s.
Datasheet (https://i.mt.lv/routerboard/files/RB1100Dx4_dude_edition-170613110855.pdf) not much help here.
Thank you
I am interested to know this as well.
I cannot see the usual transformer/opto-isolater arrangement required for DC-DC isolation, but they could be hiding under the 2.5" mounting bracket…
There is no special grounding connector, but you can ground the unit at the PCB mounting screws inside the case.
Hi Normis,
Is the RB1100AHx4 a positive ground, or negative ground ?
and is the DC input isolated ?
Neither is connected to ground. The DC is isolated.
About what is hiding under the mount plates
Oh look, there they are! 
Thank you Normis.
“What is old, is new again” 
The RB1100AHx4 power design looks very similar to RB532a, RB600 and RB800.
Nice work!