How to Use a Portable Generator Safely During an Emergency

Being without power can be a minor inconvenience, a major disruption or even a life-threatening emergency. One of the best and easiest ways to keep the lights on — as well as the fridge, air conditioning and television — is to get a portable generator. They’re not as expensive as whole-home generators (or replacing a fridge and deep freezer full of food), and they can be a lifesaver when you’re looking at days on end without power.

I’m a licensed electrician, and when I was working in the field, we constantly used portable generators. We powered job trailers, tools, and heaters for those cold Minnesota winters. But generators can be dangerous if they’re not used safely, so knowing what you’re doing is important. Below, I’ll explain how to use a generator correctly so you can get on with your life when the power goes down.

How To Use a Portable Generator Safely

Today’s portable generators have multiple safety controls like overload protection and low-oil sensors, but a generator is only as safe as you make it. Operator error causes more injuries than defective generators by a wide margin, so stay safe by following these portable emergency generator rules:

Keep It Outside and Far Away

Carbon monoxide (CO) is a colorless, odorless gas produced by combustion engines like the one in your generator. In high concentrations, it can kill you in minutes. Even at lower levels, CO can cause headaches, nausea, disorientation and neurological symptoms. To avoid these dangers, keep a running generator at least 20 feet from your home, especially any open windows or doors.

Every construction site I ever worked on required CO monitoring whenever we used generators or worked in poorly ventilated spaces, like manholes. No matter the concentration, you’ll never know CO is present until it’s too late, so even if you keep your generator out in the driveway, have a few carbon monoxide detectors on hand to monitor your home for deadly gas.

Place it on Level Ground

Most portable emergency generators don’t have oil pumps; instead, they rely on splash lubrication systems. As the crankshaft rotates, an extension on the connecting rod between the piston and crankshaft splashes oil up into the cylinder. If you place your generator on a slope, the oil will pool to one side, preventing even distribution. This can result in overheating and engine failure.

A generator with a low-oil sensor shuts itself off if it detects a low oil level, which can be triggered if it sits at an odd angle. If you have no choice but to set up your generator on a slope, prop up the downhill side on blocks to avoid power disruption.

Use Fresh Gas Only

It doesn’t take long, a few months or less, for gasoline to break down and cause starting problems in small engines like the one in your generator. Gummy, stale gas clogs up carburetors. Today’s gasoline often contains ethanol, which attracts moisture that causes corrosion. Generator manufacturers recommend using fresh gas with an added stabilizer, so don’t skip it. Keep the ethanol content to 10% or less.

Propane doesn’t have the same storage limitations as gasoline, so if you have a propane generator or a dual-fuel like mine, keeping a full propane tank around for years is OK. The tank itself will be the limiting factor, so check for an expiration date stamped on the metal if you’re refilling the same tank repeatedly.

Choose the Proper Extension Cords

Running a generator requires extension cords unless you install a manual transfer switch next to your electrical panel. Extension cords can be weak links in electrical installations, especially if you buy the wrong ones. Look for heavy-duty, outdoor-rated cords with three prongs. Never use a cheap, 2-prong indoor cord, and make sure the size is appropriate for what you’re plugging in.

Most of the time, 12-gauge extension cords will work fine if you’re running your fridge, small window A/C and computer chargers. Never go smaller, and look in your generator manual for specific appliance recommendations. It’s also important that the cords not be excessively long (max 100 feet), or you get what’s called “voltage drop.” Your stuff may cut out or struggle, and you could even damage your appliances.

Let It Cool Down Before Refueling

When filling your generator with gas, shut it down and allow it to cool for at least 30 minutes. Generators get hot, and gas cans are notoriously awkward to pour (or maybe that’s just me). Fires could occur if you spill gasoline on your generator or a spark catches the fumes coming from the can.

After you’ve filled the tank, don’t place the gas can right next to the generator. Today’s approved gasoline storage containers are often plastic. If the hot exhaust or metal parts of your generator melt through the plastic gas can, you’ll have a huge, ignitable mess on your hands.

Store Gasoline Safely

Gasoline must be stored in approved containers, so two 5-gallon cans must be kept ready for an emergency. It’s worth having two, so you can fill one while the other is being used. If there’s a run on gas, like there was here in my Texas neighborhood the last time we had a major power outage, you’ll be covered. For easier, safer pouring, consider spending a little more on high-quality steel gas cans with trigger control valves.

Keep gas cans away from boilers, water heaters and other appliances with pilot lights.

Never Backfeed Your Generator

Backfeeding happens when electrical current flows in the opposite direction than it’s supposed to. Instead of power flowing into your home, it flows “back” to the electrical grid. People can do this intentionally and properly, like when selling back solar-generated power to a utility, or unintentionally and improperly, by connecting a portable generator to house electrical wiring.

Extension cords have male and female ends, but sometimes people rig up male-male cords to connect a generator receptacle to a house receptacle and feed electricity to the entire house. This is illegal. Because the current flow isn’t properly isolated from the electrical grid, an electrical worker fixing a downed power line or other problems after a storm can be electrocuted.

As an apprentice working inside 277-volt switchgear, I was shocked by a back-fed circuit even though we had locked out the power. I was lucky to only go to the emergency room. Backfeeding kills electrical workers. Don’t do it.

Keep It Covered

Water and electricity don’t mix, whether you’re using a hair dryer in the bathroom or operating a portable generator in your yard. It only takes a few milliamps of electrical current to injure or even kill a person, so never operate a generator in the rain, or touch it with wet hands. Build a temporary canopy if weather conditions aren’t favorable, but keep it outside and 20 feet away from your home. Don’t bring the generator inside, under a carport or in your garage, even with the doors open.

FAQs

How long can a house run on a backup generator?

A generator will run as long as it has fuel and it doesn’t break down. Portable generators have an estimated lifespan of 2,000 to 3,000 hours, but well-maintained, high-quality generators can last much longer.

What is the difference between a backup generator and an emergency generator?

The terms backup, emergency and standby generators are often used interchangeably, but in the electrical industry, emergency and standby are generally used to describe permanently-installed, whole-building generators that switch on automatically when the power goes down. “Backup” is a general term that can describe any number of generators, portable or stationary.