Due to increasing traffic in Sydney's suburban network at the beginning of the century, the NSWGR introduced the C30 as a class of 4-6-4T tank locomotives with a high adhesive weight and relatively small drivers for rapid acceleration. Beyer, Peacock & Co. built 95 between 1903 and 1917 and the NSWGR built 50 more in their own Eveleigh Railway Workshops.

When the Sydney suburban network was electrified in the late twenties, many locomotives became superfluous. For use on country branch lines, 77 were rebuilt into the 4-6-0 class C30T tender locomotives between 1928 and 1933. For this the rear frames were shortened, the water tanks were removed and tender of older withdrawn locomotives were added. Between 1940 and 1957, 28 of these were superheated and received larger cylinders and extended smokeboxes.

Soon the C30T was widely distributed around branch lines in the state. The original C30 tank locomotives were now used on the remaining non-electrified lines around Sydney and on branch lines without turntables. Later they were also used as shunters. All locomotives of the original and the rebuilt classes were withdrawn between 1957 and 1973. Five C30 are still existing, of which 3112 is being under overhaul. From the C30T seven have survived, with 3001 in an operational state and 3016 under overhaul.