Identify Essential Systems and Equipment - What do you need to keep your business operating? These may include heating, ventilation, and air conditioning systems; industrial equipment and major appliances, such as refrigerators and freezers; lights (interior and exterior), computers, and other office equipment; pumps, including sump pumps, sprinkler system pumps, and well water pumps; and alarm systems. Some of these systems and equipment may have to operate continuously, while others may be needed only during normal business hours.

Choose the Generator's Fuel Source - Backup generators are typically powered by either diesel fuel or natural gas, and both have associated advantages and disadvantages. Speak with your utility company or an expirienced electrician, engineer, and/or sales consultant who knows exactly what kind of generator may be needed based on the building's specifications. Fuel sources may present additional safety and permitting issues.

Choose the Generator's Size - Generators must be sized to either handle the full electric load of the facility, or with an automated or manual transfer switch that sheds enough of the facility's electric load to prevent the backup generator from overloading. You will need more power to restart systems and equipment when the power fails than to continue operating them after startup.

Determine Any Utility Requirements or Building Codes - Before you buy a generator, ask your utility company and local building departments if they have regulations that govern the use of emergency power equipment. Specifically check the requiremnts for the use of automatic or manual transfer switches or mechanical disconnecting means to ensure the safety of power company personnel working to restore power. Generators should be installed by qualified technicians in accordance with utility company regulations and local and national building and electric codes.