Final answer:
A G2 certification holder can work on gas-fired equipment with a maximum input of 400,000 BTU/h.
Step-by-step explanation:
The holder of a G2 certification may install and service gas-fired equipment with inputs up to 400,000 BTU/h. This question relates to the types of equipment an individual with a G2 certification is qualified to work on, and understanding the BTU (British Thermal Unit) input limit is crucial for safety and compliance with regulations regarding the installation and servicing of these types of equipment.