A generator should be sized from the equipment that must operate, not from house size or a generic wattage band. Write down the exact loads, their voltage, and whether they need additional power at startup.

Build the load list

Use appliance nameplates and manuals to record running and starting demand for the refrigerator, freezer, sump pump, furnace blower, well pump, medical equipment, communications, lighting, and any other essential load. Decide which items must run simultaneously. Leave design margin rather than selecting a generator whose output exactly equals the arithmetic total.

Check whether any required load uses 240 volts. A 120-volt-only generator cannot supply it. For medical or life-support equipment, use the equipment maker’s backup guidance and a professionally designed emergency plan.

Choose the connection method

Individual appliances can use correctly rated outdoor extension cords when the generator and appliance instructions allow it. Match conductor size, length, plug, and weather rating to the load.

Selected household circuits require a listed transfer switch or interlock, inlet, and installation appropriate to the electrical system. Use a qualified electrician. Never energize household wiring by connecting a generator through a receptacle.

Plan the operating location first

Fuel-burning generators produce carbon monoxide. CPSC says to operate a portable generator outside only, at least 20 feet from the house, with the exhaust directed away from the home and any other building someone could enter, and with windows and other openings in the exhaust path kept closed. CPSC also says never to run one inside a home, garage, basement, crawlspace, or shed.

Storage and operation are separate plans: pick the outdoor run spot, and how the cords or inlet cable reach it, before you buy. CPSC also recommends battery-operated CO alarms, or CO alarms with battery backup, on each level and outside separate sleeping areas.

Fuel, weather, and maintenance

Choose fuel only after checking storage rules, availability, runtime, and the exact generator’s output on that fuel. Follow the manual for refueling, weather protection, oil, filters, battery care, exercise, and long-term storage. Do not refuel a hot or running unit.

Sources and limits

This checklist does not pick a wattage for a particular home. The load inventory and the installation decide that.