The rain was coming down sideways on I-75 when I pulled off for fuel. Half a dozen cars were already stacked at the pumps, hazard lights blinking. Every one of them was pointed at a station that was completely, embarrassingly dark. The canopy was out. The price sign was out. The only thing lit was a little battery-powered EXIT sign over the door, glowing like a punchline.
Think about that for a second. A gas station. A place that literally sells the fuel that powers generators. And when the grid went down, it couldn’t sell a single drop — because nothing there could pump it without electricity. The irony wrote itself. I sat in that line for twenty minutes before I gave up.
That night stuck with me. Because gas stations are one of the most misunderstood backup-power loads I know. Everybody thinks: pumps, a few kilowatts, done. Honestly? The pumps are the easy part. Everything else is where station owners get burned.
Walk a station like an electrician and the load list gets long fast. Each fuel dispenser is fed by a pump motor — usually a submersible turbine pump down in the tank, drawing roughly 1.5 to 3 kW per product line when running. Six dispensers, figure maybe 8 to 12 kW of pumping load if several are running at once. That’s the number everybody quotes.
Then comes the rest of the store. Canopy lighting — those bright white panels that make the station visible from half a mile away — can pull 5 to 10 kW on an older metal-halide canopy, less if it’s been converted to LED. The POS registers and card readers are small, a few hundred watts, but they are non-negotiable: no card readers, no sales. The automatic tank gauging system and its leak-detection alarms legally have to keep running in most jurisdictions — that’s the law, not a nicety. Add the cooler and freezer cases, the coffee machines, the ice machine, the air compressor, the back-office HVAC, and the car wash if there is one. A car wash alone can be a 30 to 60 amp motor load, and its inrush current at startup is the thing that trips undersized breakers.
Here’s the thing nobody tells the station owner: the dispenser motors are polite loads. The car wash, the HVAC compressor, and the refrigeration are not. Size for the polite loads and the impolite ones will let you know about it the first hot afternoon after a storm.
Rough numbers, from stations I’ve actually worked on. A small station — four to six dispensers, no car wash, a modest convenience store — usually lands somewhere around 30 to 60 kVA once you totalize everything honestly. Add a car wash and you’re typically looking at 60 to 100 kVA, sometimes more if the store is big.
Those are ballpark figures, not quotes. The real answer always comes from an honest load list with motor starting currents included. A submersible pump that draws 2 kW running can pull three to five times that for a fraction of a second at startup. Multiply that across six dispensers all firing up after a transfer, and a “30 kVA will cover it” guess turns into a generator that stalls on the first inrush. (The step-by-step sizing process is the same one I walk through in my generator sizing guide — the steps are identical, only the load list changes.)
After the brutal hurricane seasons of 2004 and 2005, Florida looked at the same dark-station problem I’d seen on I-75 and did something about it. The state wrote it into law: gas stations on designated evacuation routes have to be generator-ready — prewired, with a transfer switch installed, so a portable generator can be rolled up and plugged in when a storm is coming.
Not “have a generator sitting there.” Just be ready for one. That’s a smart distinction, and it’s one more places should copy. A transfer switch costs a fraction of a permanent genset, it doesn’t need exercise runs or fuel maintenance, and it turns a two-day outage from a catastrophe into a logistics errand. I’ve told station owners in hurricane country the same thing: the switch is the cheap part. Buy the switch now, rent or buy the generator when the forecast says so.
The switch also matters for a reason most owners never think about until an inspector shows up: an automatic transfer switch is what keeps your generator from backfeeding the dead grid. Backfeeding kills linemen. No inspector will ever forgive it, and neither will a utility.
Here’s a detail that trips up first-timers. Most of the stations on any given highway sell gasoline. A diesel standby generator needs diesel. If the station doesn’t retail diesel, the generator’s fuel has to come from somewhere else — a separate aboveground day tank or a bulk tank, with its own containment, its own vents, its own maintenance.
And before anyone gets clever: you can’t just plumb the generator into the station’s underground gasoline tanks and call it a fuel supply. Gasoline in a diesel engine is a fast way to own a very expensive paperweight. Even at a station that does sell diesel, the generator should have its own dedicated supply arrangement — clean fuel, filtered, and tested — not a jury-rigged line off the retail plumbing. Fuel quality kills more standby generators than any other single cause, and I’ve seen the filter bowls to prove it.
I’ve walked enough of these sites to have a greatest-hits list. It barely changes.
1. Sizing for the pumps and forgetting the store. The owner does the math on six dispensers, buys a 25 kVA set, and then the first outage arrives: the car wash breaker trips, the coolers warm up, the card readers die. Size the whole station or don’t bother.
2. A generator that has never carried a real load. The set gets its weekly exercise run — unloaded, ten minutes, everything looks fine on the controller screen. Then the storm comes and the first thing it learns about the station’s actual load is the inrush current. A green exercise log is not proof of readiness. If the generator has never run the station, it hasn’t been tested.
3. Putting the generator where it doesn’t belong. Gas stations have classified hazardous areas — around dispensers, tank vents, fill points. The rules (NEC Article 514 in the US) exist because fuel vapor plus ignition is exactly as bad as it sounds. I’ve seen generator sets and their fuel tanks shoehorned into spots that made me nervous: vented toward the canopy, cable runs crossing classified zones. The generator belongs outside the classified areas, with proper setbacks, and its exhaust pointed away from everything that sells fuel.
Look, I get it. A gas station is a thin-margin business. A standby generator is a five-figure purchase that sits there doing nothing 99 percent of the time. It’s the easiest line item in the world to cut.
But here’s what I tell owners, and I mean it: the generator at a gas station isn’t backup power. It’s inventory protection. During an extended outage, the station with power becomes the only station — every car in a five-mile radius with a quarter tank is coming to you. The revenue from one bad storm week can pay for the generator. The stations that stayed lit during the last big outage in their area all tell the same story. The dark ones tell another one.
And the cheapest version of this whole conversation is the Florida model. Prewire the transfer switch. Do it during any electrical renovation, when the electrician is already there and the incremental cost is small. Then, when the forecast turns ugly, the generator is a phone call away instead of a rewiring project away. If you want a second opinion on the load list, talk to us — we’d rather size it right than size it twice.
I still think about that line of cars on I-75, hazards blinking in the rain, pointed at a building full of fuel it couldn’t buy. Don’t be that station.
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