The accuracy table for the sb-9632 can be found in the manual on page 41 at the link below.
http://forums.ni.com/t5/Real-Time-Measurement-and/Powering-sbRIO-with-a-DC-DC-converter/m-p/2336818#...
The same manual addresses ground connections on page 15 which may address your concerns about blowing any fuses.
Dave C.
Applications Engineer
National Instruments
