Great advice - Thank you I will add them in.
Can you advice a part number for the 600V diodes if you have used similar before?
Presumably there will be a small voltage drop over the diode too?
I would use this type of diode, you could pick any other diode provided it's rating is above max current draw in fault conditions, this one just happens to available?
http://www.ebay.ie/itm/WIND-TURBINE-SOL ... 3a60e3f482
And then use this type of 20mm fuse holder
http://www.ebay.ie/itm/20mm-PCB-Mount-F ... 53f96008ee
and solder the diode to one side of the fuse holder, then you will have a fused the dc supply from power supply + steering diode to prevent one power supply fault effecting the other?
Expect about 0.6volt drop across the diode ?
I would equal DC voltage on both power supplies then you will have shared current draw from each supply, not that it makes much difference as the normal current demand will be very low for the CCR?
Also setup and test on a old routerboard first using the 2.1mm DC input jack and when all is ok transfer to CCR.
Forgot to ask but is it only just one device (CCR) you will be powering with dc supply or do you have other devices also requiring dc supply at this location?