The BC547B has Vcbo=50V, Vceo=45V, Vebo=6V, where-as the BC548 in original circuit has Vcbo=30V, Vceo=30V, Vebo=5V, rest of the parameters being pretty same as per datasheet (hFE:220-450). 1HP Water pump (220VAC, 800W) - One thought is to use higher current....