How to Use a Portable Generator

1. Placement First, Always

This is the step that kills people when it is done wrong, so it comes before everything else including reading the rest of this page.

A portable generator runs outdoors only. Not in a garage, not in a garage with the door open, not in a carport, not in a breezeway, not in a shed, not on a covered porch, and not under a deck. Carbon monoxide is colourless, odourless, heavier than the air you are breathing in the sense that it lingers, and it accumulates in enclosed and semi-enclosed spaces faster than people expect. An open garage door does not make a garage safe.

Keep it well away from the building and from any opening. The commonly cited minimum is around twenty feet from the house, with the exhaust directed away, and no doors, windows, vents or air intakes within that radius. Pay particular attention to things you might not think of as openings: a dryer vent, a bathroom extractor, a window air conditioner, a basement hopper window.

Fit working carbon monoxide alarms inside the house, on every level and near sleeping areas, and test them before storm season rather than during it. Many newer generators have a CO shutoff sensor built in, which is a genuine safety advance and is not a reason to place the machine any closer.

Then think about the surface and the weather. Level, firm ground, so the oil sits where the dipstick expects it. Out of standing water. If it is raining, a purpose-made running cover or an open-sided canopy with generous clearance on all sides, never a tarpaulin draped over it, which traps heat and can melt or ignite. Our guides on where to place a generator outside and running one in the rain cover both in detail.

2. Before You Pull the Cord

Four checks, none taking longer than a minute, that prevent the common first-day failures.

Oil

Check the level on level ground before every start. New generators frequently ship without oil, and running one dry for even a short period destroys it. Most have a low-oil shutdown that will refuse to start, which is the sensor doing its job and is often misread as a faulty machine.

Fuel

Fresh fuel, ideally with stabiliser if it has been stored. Gasoline degrades in a few months and stale fuel is the single most common reason a generator will not start after a year in the shed. Check the fuel valve is open, and if the unit has a choke, that it is set for a cold start.

Nothing Connected

Start the generator with no load at all. Unplug everything, and if it has circuit breakers on the panel, leave them off. Starting under load is hard on the alternator and can stall the engine, and it exposes whatever is plugged in to the voltage and frequency fluctuation of a starting engine.

Air Filter and Surroundings

Glance at the air filter, especially if the machine has been stored or used in dust. Clear the area around the generator so air can move freely on every side, and check that the exhaust is not pointing at anything flammable or at a wall that will reflect fumes back.

If this is the first run of a brand new generator, read the break-in section of the manual. Many specify a light load for the first few hours and an early oil change at 20 to 30 hours, and following that genuinely affects how long the engine lasts.

3. Starting It

The sequence is the same across almost every recoil-start portable, with small variations for electric start and inverter models.

Open the fuel valve. Set the choke to closed or start position if the engine is cold; if it has been running in the last half hour, leave the choke open or part-way. Switch the engine switch to on. Then pull the recoil handle: draw it slowly until you feel resistance, then pull firmly and smoothly through. Do not yank from a slack cord, and do not let the handle snap back — guide it in.

Once it fires, let it run for a few seconds and then open the choke progressively as the engine warms. Going straight to full choke-off on a cold engine usually stalls it. Then let it run at no load for two to three minutes to warm up and settle to a steady speed before you connect anything.

On an electric-start model the sequence is the same with a key or button in place of the cord, and the same warm-up applies. On an inverter generator, check whether eco mode should be off for starting; many want it off until the load is connected, because eco mode idles the engine and can make starting a large load harder.

If it will not start, the order of likely causes is: fuel valve closed, stale fuel, choke wrong for the temperature, low oil shutdown triggered, and spark plug fouled. That covers the large majority. A generator that runs but produces no power is a different fault entirely, and our guide on a generator that runs but has no output covers it.

Let it settle. A generator that has just started is not yet at stable voltage and frequency, and electronics connected during that window are exposed to exactly the kind of fluctuation they dislike. Two to three minutes costs nothing.

4. Adding Loads, Largest First

This is the part people improvise and it is where equipment gets damaged.

Connect loads one at a time, largest starting draw first, letting each one settle before adding the next. The reason is inrush: motors draw several times their running current for the first second or two, and a fridge compressor or a well pump starting onto a generator already near capacity will either trip the breaker or drag the voltage down enough to harm other things connected.

So the order is: the biggest motor load first, then the next, then resistive loads like heaters and kettles, then electronics last. If your load list includes a sump pump, a fridge and a freezer, start the pump first, let it settle, then the fridge, then the freezer, spacing them out.

Keep total running load comfortably below the generator's running watts figure, not its starting or peak figure. Sitting at 50 to 75 percent leaves headroom for inrush when a compressor kicks in unexpectedly, runs the engine in its comfortable range, and stretches fuel considerably. Our generator wattage chart lists typical draws for planning.

Use the right cords. Heavy-gauge outdoor-rated extension cords, in good condition, with intact ground pins, sized for the load and the distance. An undersized cord drops voltage over its length, which makes motors run hot and can damage them, and it is a fire risk in itself. Our guide on generator extension cord sizing covers gauges and lengths.

And never plug the generator into a wall outlet to power the house. Backfeeding bypasses every protective device, can kill utility line workers, and is illegal essentially everywhere. If you want house circuits powered, that means a transfer switch or an interlock, which our comparison of the two covers.

5. While It Runs

A generator running well needs very little attention, and the little it needs prevents the expensive problems.

Listen to it. A steady note is a healthy generator. Surging, hunting up and down, or a sudden change in pitch when nothing has been plugged in usually means fuel delivery, a dirty carburettor or a load problem, and is worth investigating rather than ignoring.

Check the oil at every refuel. The machine is already shut down and cooling at that point, so it costs nothing, and it is the single check that prevents engine destruction over a long outage. Our guide on continuous runtime covers why oil rather than fuel is the real constraint.

Keep the area clear. No fuel containers next to the machine, nothing flammable near the exhaust, nothing leaning against it, and enough space on all sides for air to move. A generator that has been running for hours has a very hot exhaust and people burn themselves on it routinely.

Do not refuel it running or hot. Shut down, wait several minutes for the exhaust and engine to cool, then refuel. Petrol on a hot muffler ignites, and this is the leading cause of generator fires during outages.

Watch the load if circumstances change. A sump pump cycling on while the kettle is boiling can take a generator over its limit and trip a breaker, which in the middle of a storm means the pump stops. Think about what might start unexpectedly rather than just what is on now.

6. Shutting Down Properly

The reverse of the start-up sequence, and skipping it is how alternators and appliances get damaged.

Disconnect the loads first, one at a time, before stopping the engine. Turn appliances off at their own switches, then unplug them, then switch the generator's breakers off. Killing the engine with everything still connected drops voltage and frequency through the floor as it spins down, and that is exactly the condition that harms motors and electronics.

Let it run for a minute or two at no load before stopping. This lets the engine cool evenly and the alternator settle, and on a hard-working machine it makes a genuine difference to longevity.

Then stop the engine with the engine switch. If you are storing it for more than a few weeks, close the fuel valve first and let the engine run until it stops on its own, which empties the carburettor and prevents the varnish and gumming that make a stored generator hard to start next time. This single habit prevents most storage starting problems.

Let it cool fully before covering it or moving it into a shed. A hot generator under a cover is a fire risk, and it is also how condensation gets trapped against the metal.

If you are between blocks in a multi-day outage rather than finishing, the same sequence applies each time: loads off, run a minute, stop. The stops are also your opportunity to check oil and top up fuel, so they are not lost time.

7. After the Outage

What you do in the hour after the power comes back determines whether the generator starts next time.

Deal with the fuel. Either run the carburettor dry by closing the fuel valve and letting the engine stop on its own, or fill the tank completely and add stabiliser. Both approaches work and they solve the problem in opposite ways: one removes the fuel, the other removes the air space where condensation and oxidation happen. A half-full tank with untreated fuel is the worst of both.

Change the oil if you accumulated meaningful hours. An outage can easily consume a full service interval, and dirty oil sitting in a stored engine for a year is worse than dirty oil in a running one. This is also the moment to note the hours in a log if your machine has an hour meter.

Clean it and check it over. Wipe off dust and debris, check the air filter, look for anything that has vibrated loose, and check the cords for damage while you are coiling them. Generators accumulate small problems during hard use and they are far easier to find now than during the next storm.

Store it somewhere dry, covered once cool, with the fuel dealt with and the cords and oil kept alongside it. Our guide on storing a portable generator covers the off-season routine properly.

Then exercise it. A generator started and run under a modest load for fifteen to twenty minutes every month or two is dramatically more likely to start when you need it than one left untouched for a year. Put it in the calendar, because this is the maintenance step everyone agrees with and nobody does.