Home generators: types, sizing and safety rules

If you live in a house, especially in a rural area where outages sometimes last days, a generator is the surest way to have unlimited power as long as you have fuel. But generators are also a common cause of carbon monoxide poisoning and electrical accidents during outages. Before buying one, it’s worth knowing how to choose and use it.

Types of generator

Type	Pros	Cons	Best for
Inverter	Quiet, stable power, low fuel use	Pricier per kW, usually under 4 kW	Electronics, boilers, fridge
Conventional (with AVR)	Cheap, high output	Noisy, less stable power	Pumps, tools, large appliances
Standby with auto start	Starts by itself in an outage, powers the whole house	Expensive, professional installation	Large houses, medical devices

Fuel: gasoline is most common but degrades within months. Diesel keeps longer and is safer to store. Propane or dual-fuel generators have the advantage that the gas bottle keeps for years.

How to size it

1. List the appliances you want to run at the same time.
2. Add up their running wattage (from the label).
3. For motor-driven appliances (fridge, pump, compressor), add the starting surge, two to three times the running power.
4. Add a 20 to 25% margin.

Example: fridge (150 W, 450 W to start), gas boiler (120 W), 5 LED bulbs (50 W), router and phones (50 W), TV (80 W). Running total: 450 W; when the fridge starts, about 750 W. A 1 to 2 kW generator is enough. Add a 1,000 W submersible pump (2,500 W to start) and you need 4 to 5 kW.

Safety: the rules that save lives

Never run a generator inside your home, garage, basement, shed or under a closed porch, not even with the door open. Keep it outdoors, several meters from doors, windows and air intakes, with the exhaust pointing away from the house. Fit carbon monoxide alarms indoors.

• Connecting to your home’s wiring must be done only through a transfer switch (manual or automatic) installed by a licensed electrician. Otherwise, generator power can feed back into the grid and electrocute the line workers fixing it. Without a transfer switch, use heavy-duty outdoor extension cords straight from the generator to the appliances.
• Grounding: follow the manufacturer’s instructions.
• Rain and snow: don’t run it in water or uncovered in the rain without an open shelter designed for generators.
• Refueling: switch off the generator and let it cool before adding fuel. Gasoline spilled on a hot engine can ignite.
• Noise: conventional generators are very loud. Respect quiet hours and your neighbors.

Maintenance

• Start it once a month for 15 to 20 minutes with a small load.
• Change the oil after the first hours of running-in, then per the manual.
• Drain the carburetor or use fuel stabilizer if it stands unused for long.
• Keep spare oil, a spark plug and an air filter on hand.

Generator or power station?

	Generator	Power station
Energy available	Unlimited, as long as you have fuel	Limited by the battery, rechargeable
Indoor use	Never	Yes
Noise	High (inverters less so)	Almost none
Maintenance	Oil, fuel, monthly start	Almost none
Best for	Houses, long outages, big appliances	Apartments, short and medium outages

For apartments the choice is clear: a portable power station. For houses, the ideal combination is a station for night-time and essentials, plus a generator to recharge it and run the big appliances.