Hi
C282...
a seperate service room(s)with a 2 hr fire seperation from the rest of the building or a seperate building or enclosure.

Don't forget if you are installing in vancouver the testing had to be done by an ASTT registered technician.
( i.e. on start up the 1 hour operational test, the 4 hour full load test and the 1 hour LTP test. .....also the yearly 2 hour full load test )

The new installations I have come across, seem to have both generator/ATS in one room and in seperate rooms., all are diesel sets.

strange the sharing fuel.
C282 6.3.7 states the fuel tank and fuel used for an emegency generating set shall be reserved exclusively for the generator set.

don't forget to check the BC fire code / building code and NFPA 37 in addition to C282
cheers
Jerry