If you’ve ever huddled through a thunderstorm, lights flickering, fridge humming uncertainly, and that quiet anxiety about power outages creeping in, you’ve probably wondered: Can I actually use my emergency power supply (EPS) while a storm is still raging outside? As someone who’s spent the last seven years working for an emergency power supply company—talking to homeowners, small business owners, and even first responders about how to stay powered safely—I get this question all the time. It’s not just a random worry, either. Thunderstorms cause more than 100,000 power outages in the U.S. alone each year, and half of those events happen while lightning is still striking nearby. So the answer isn’t a simple yes or no—it depends on a few key factors, and I’ve seen way too many people make mistakes that put their safety, their gear, or their EPS at risk. Let’s break this down like we do for every customer who calls our support line. Emergency Power Supply
First, let’s get one thing straight: Thunderstorms and electricity don’t mix. The biggest threat during a storm isn’t just the lightning that hits a power line miles away—it’s the surge that travels through that line to your home or business. A lightning strike can create a power surge hundreds of times stronger than your home’s normal voltage, and that surge doesn’t care if your main power is off or if you’re running on an EPS. That’s the core of this question, and it’s where most people go wrong.
Now, not all emergency power supplies are the same. If you’re talking about a portable gas-powered generator you picked up at a hardware store, the answer is almost always no—you shouldn’t run it during an active thunderstorm. I’ve had a customer tell me last summer that he fired up his portable generator to keep his sump pump running during a storm, only for lightning to strike a line 200 yards from his house and send a surge back through the generator’s wiring, melting his control panel and frying his sump pump. That’s a real story, and it’s why our team drills this into every sales pitch. Portable gas generators are ungrounded, open-frame machines by design (for ventilation), so they offer zero protection against surge events from lightning. Even if you plug them into a transfer switch (which is non-negotiable for portable gens), they’re still exposed to surges that can damage both the generator and anything you power with it.
But what about the other type of emergency power supply—standby generators, or even the modern lithium-ion portable EPS units that are designed for home backup? That’s where the lines get blurry, and it’s not a one-size-fits-all answer. Let’s start with standby generators, which are permanently installed outside your home, wired directly into your electrical panel, and grounded to your home’s main grounding system. Our company installs these for a lot of our residential customers, and we always tell them: If you have a standby generator that’s properly installed, grounded, and has a built-in surge protector, it’s safe to run during a thunderstorm—with one big caveat. The only time you shouldn’t run it is if lightning is actively striking within 200 feet of your home. That’s the rule we get from electrical safety experts, and it’s a distance that gives the ground time to absorb the surge energy before it reaches your generator.
Wait, but why is that different from a portable generator? Because standby generators are hardwired to your home’s grounding system, which includes metal rods driven 8 to 10 feet into the ground. That grounding system is the same one your main electrical panel uses to divert excess voltage safely into the earth. A portable generator, by contrast, relies on its own small grounding prong or a temporary rod you might stick in the dirt—and if that rod gets wet (which it will during a storm), that’s a different risk, but still not enough to match the protection of a permanent home ground.
Now, the newer lithium-ion portable EPS units—those compact, wheeled units that look like large power banks for your whole house—are a different beast altogether. A lot of our customers ask these days about these, since they’re quieter and easier to store than gas generators. I had a small café owner call me last month panicking because a storm knocked out her power, and she wanted to run her refrigeration unit and point-of-sale system on her portable EPS while the lightning was still going. We walked her through the safety checks first: Did the EPS have a built-in surge protector? Was it positioned at least 10 feet from the side of her building, away from windows and doorways? Was it plugged into a surge-protected outlet, not just directly into the unit? If all those boxes are checked, it’s safe to run. But if it’s just a basic portable power station without surge protection, and she’d plugged the fridge directly into it during a storm, she could’ve ended up with a broken fridge and a risk of electrical shock if the unit got hit by a nearby surge.
Let’s talk about the risks here, because that’s what matters most. First, electrical shock: If lightning strikes somewhere near your property, it can create a step potential in the ground—meaning the voltage between two points a few feet apart is high enough to give you a shock if you’re standing on the wet ground near your generator or EPS. That’s why we always tell customers to stay at least 10 feet away from the unit when it’s running during a storm, and never touch it with wet hands. Second, equipment damage: Even if you don’t get shocked, a surge can fry anything from your TV to your HVAC system to your garage door opener. I’ve seen a customer’s whole home theater ruined because he ran his portable generator during a storm without surge protection—cost him over $2,000 in repairs. Third, for gas-powered generators specifically: Carbon monoxide poisoning. A lot of people don’t realize that even if you think the storm is “over,” you might still have CO buildup near your home, especially if you run the generator in a garage or under an overhang. That’s a whole separate risk, but it’s amplified when people are distracted by a storm and forget basic safety rules.
Wait, but what about the myth that you should never use any EPS during a thunderstorm? I get that myth a lot, from customers who read old forum posts online. That myth comes from the early days of generators, when almost all units were ungrounded portable models with no surge protection. Today’s technology has changed that. Our standby generators, for example, come pre-wired with an integrated surge suppression system that can divert up to 100,000 amps of surge current—way more than what a typical lightning strike near a home would produce. We test every single unit before it leaves our warehouse, and we require our installers to test the grounding system on site to make sure it’s up to code.
But let’s not forget the “what if” scenarios that come with storms. What if the storm is so bad that the power lines themselves get damaged? What if a tree falls on the line right next to your house? Running an EPS in that case is even more important, because you might be without power for hours or days. But you still have to follow the rules: Keep the unit grounded, keep it away from the building, and don’t plug things into it that you don’t need. Our commercial customers—like grocery stores, hospitals, and data centers—run their standby generators all the time during thunderstorms, because they can’t afford to lose power. The only time they shut down the EPS is when lightning is actively striking within a 100-foot radius, per their site safety protocols.
Another thing I always tell people is to test their EPS before the storm hits. I can’t stress that enough. Last year, a customer called us at 2 a.m. during a storm saying his generator wouldn’t start, and his sump pump was about to fail. We got a technician out there in 45 minutes, but it turned out he hadn’t tested the generator in over a year, and the fuel had gone bad. If he’d tested it a week before the storm, he could’ve added fresh fuel and avoided the whole problem. Same with portable EPS units: Check the battery level, make sure the surge protector is working, test the outlets a few days before bad weather is forecast.
Let’s also talk about when you should absolutely not run an emergency power supply during a thunderstorm. First, if you’re using a portable gas generator that doesn’t have a transfer switch. Plugging a portable generator directly into a wall outlet is not only dangerous—it’s illegal in most places, because it can backfeed power into the main grid and electrocute line workers who are trying to fix the outage. Second, if you can see lightning or hear thunder within 5 miles of your location, and your unit doesn’t have a dedicated surge protection system. Third, if you’re running the generator or EPS in an enclosed space, like a garage, basement, or even on a covered porch. Even with ventilation, enclosed spaces trap carbon monoxide, and they also increase the risk of surge damage if the unit is too close to your building. Fourth, if you have a medical device that requires power—like a oxygen concentrator or a heart monitor—don’t rely on a portable EPS during a storm, unless you’ve tested it with your device and have a backup plan. Medical devices are sensitive, and a surge could damage them, so we always recommend having a fully charged battery backup for medical equipment separate from your general EPS.
I know this all sounds like a lot of rules, but it’s simple when you break it down. The core takeaway is: Modern emergency power supplies can be safely used during thunderstorms, but only if they’re installed or operated correctly, with proper grounding and surge protection, and you follow basic safety guidelines. Too many people see a storm coming and panic, grab the first generator they have, and start it up without checking anything. That’s when mistakes happen.
As someone who’s been in this business for years, I’ve seen the good, the bad, and the ugly when it comes to emergency power during storms. I’ve helped a family keep their baby’s isolette running during a tornado outage, and I’ve helped another customer replace a portable generator that was damaged by a surge because he didn’t know the basics. That’s why our team is always available to talk to customers, whether they’re buying their first EPS or they’ve had one for 10 years. We don’t just sell units—we give guidance, because safety is non-negotiable.
If you’re preparing for storm season, or you have questions about whether your current EPS is safe to use during a thunderstorm, don’t guess. Reach out to our team to connect for a procurement consultation. We can help you assess your needs, make sure your system is up to code, and give you clear guidelines for using it safely when the next storm rolls in.
Explosion-proof Emergency Lights References:
- Electrical Safety Foundation International. (2022). Lightning and Electrical Safety. Retrieved from ESFI.org
- National Fire Protection Association. (2021). Portable Generator Safety Guidelines. Retrieved from NFPA.org
- International Association of Electrical Inspectors. (2020). Standby Generator Installation and Safety Standards. Retrieved from IAEI.org
- Occupational Safety and Health Administration. (2023). Carbon Monoxide Hazards from Portable Generators. Retrieved from OSHA.gov
Zhongshan Tuoming Lighting Technology Co., Ltd.
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