A few summers ago, I watched a stretch of businesses on a Brooklyn commercial strip lose their air conditioning within days of each other during the same heat wave. Not a blackout. The lights stayed on, the registers worked, the signs stayed lit. The AC units just stopped keeping up, one after another, on some of the hottest days of the year, on a block where half the shops were serving food or standing full of customers who had walked in specifically to get out of the heat.
Every business owner I talked to that week assumed their unit had failed. Most of them were wrong.
Every summer, when demand for electricity spikes during extreme heat, Con Edison reduces voltage across parts of New York City on purpose. It is not a malfunction and it is not a secret. ConEd has done it for years, and it happened repeatedly again this past July, cutting voltage by 5 to 8 percent in parts of Brooklyn, Queens, the Bronx, and Westchester to protect grid equipment from overheating and to prevent a smaller problem from becoming a full outage.
From the utility's side, it works. A voltage reduction keeps the broader system online while crews handle repairs in the areas under the most stress. From the inside of your business, it can look and feel like your own equipment is failing, even when it is functioning exactly as designed for the power it is actually receiving.
⚡ Worth knowing: ConEd manages the city through 65 separate underground electrical networks, each dedicated to a specific neighborhood. A voltage reduction in one network has no effect on another, which is why one commercial strip can lose cooling capacity while a block ten minutes away never notices anything happened.
Air conditioning is one of the more voltage-sensitive systems in a commercial space, because the compressor is a motor, and motors do not respond gracefully to running on less voltage than they were built for. When the voltage drops, a motor tries to make up the difference by drawing more current to produce the same output. That extra current shows up as heat, as nuisance breaker trips, as a compressor that hums and struggles to start, or as a unit that runs constantly without ever quite reaching the temperature it is set to.
Most HVAC equipment is only built to tolerate a swing of roughly 10 percent from its rated voltage before performance and reliability start to suffer. An 8 percent reduction from the utility does not sound dramatic on paper. Stacked on top of an older building's wiring, a long run from the panel, or a service that was already running close to the edge of what your equipment needs, it is often enough to push a system past the point where it can keep up.
This is why the failure often looks identical to a bad compressor or a refrigerant problem. The equipment is not lying to you. It is doing exactly what underpowered equipment does. The cause just is not sitting inside the unit.
For a retail shop, losing cooling on the hottest day of the summer means customers who walk in, feel the heat, and walk right back out. For a restaurant, it means a dining room nobody wants to sit in during your best weather-driven traffic of the year, on top of the food safety risk of a walk-in cooler pulling from the same undersized service. For any business with staff on the floor, it becomes a safety and retention issue on top of a comfort one. None of that shows up as a line item. It shows up as a slower week you can't fully explain, right when the calendar says it should have been one of your busiest.
If this keeps happening to your business specifically during heat waves, and not during ordinary weeks, that pattern is worth paying attention to. It points toward a supply problem rather than a worn-out unit, and supply problems have a real, well-established fix: a buck-boost transformer.
In plain terms, a buck-boost transformer is a small transformer installed between the incoming power and your equipment that corrects the voltage before it reaches your AC, either bringing a low voltage back up closer to what the equipment actually needs, or bringing a high voltage back down. It does not generate power or replace ConEd's service. It corrects the number so your equipment is running on what it was designed for, instead of whatever the grid happens to be delivering that afternoon.
⚠️ This is not a DIY fix. Sizing a buck-boost transformer correctly depends on your actual load and your equipment's amperage, and the wiring configuration changes depending on whether you need to raise or lower the voltage. Wired incorrectly, it can make the problem worse instead of better. This is a job for a licensed electrician, not a weekend project.
Before you spend money on anything, the first step is confirming what is actually happening. Have a technician measure your incoming voltage during a high-demand period, ideally on a hot afternoon when the strain is real, not on a mild Tuesday morning when everything looks fine. A guess dressed up as a diagnosis costs you twice: once for the wrong fix, and again next summer when the same problem shows up on schedule.
The heat wave is not the surprising part. It happens every summer. Whether your business is ready for what it does to your power supply is the part still worth figuring out now, before the next one arrives.