HV Switchgear - Internal Earth Bar

HV Switchgear (IEC 62271-1, 62271-200): The size of the internal earth bus (the bar running through the entire switchgear lineup) differs from the size indicated in the type test report. Is this acceptable? Is the busbar size specified in the type test report applicable only to the main busbars and not to the earth bus? If the manufacturer provides calculations demonstrating that the earth bus size is adequate for the specified fault current and duration, can this be accepted? For example, if the short-time withstand current/duration is 25 kA for 1 second, the adiabatic equation indicates a required conductor size of approximately 175 sq.mm. In this case, would providing a 200 sq.mm earth bus (40 × 5 mm) be acceptable?