Storm outages in central NC are not rare. Tropical remnants and ice storms knock out power across Stanly County, Union County, and Cabarrus County every year. A properly sized standby generator with an automatic transfer switch means you go through an outage the same way you go through a normal day.

Getting to that outcome requires choosing the right generator. Most homeowners undersize because they focus on the cost number. Some oversize because a contractor told them to go big. The right approach is to actually calculate the load.

How generator sizing works

Generator capacity is measured in kilowatts (kW). To size a generator for your home, you need to add up the running wattage of everything you want the generator to power during an outage, and then account for the starting surge of large motors (HVAC compressors, well pumps, sump pumps).

Here is what typical loads look like for a 2,500 square foot home in the Charlotte corridor:

• Central HVAC (3-ton unit): 3,500W running, 8,000W starting surge
• Refrigerator: 200W running, 600W start
• Well pump (if applicable): 750W running, 2,000W start
• Lights, TV, outlets: 1,500 to 2,500W combined
• Electric water heater (if electric): 4,500W

A whole-home calculation for that house typically lands between 14kW and 22kW depending on whether you want to power the electric water heater and dryer as well. A 16kW or 20kW generator with a load management module is the most common residential installation in Union County.

The reason the starting surge matters is that a motor draws three to five times its running wattage for the first second or two as it spins up. If you size only for running wattage, the generator can stall the moment the HVAC compressor kicks on. That is why a 3,500W air handler needs roughly 8,000W of headroom available at the moment it starts. We build that surge into the calculation so the unit never gets caught flat-footed when the largest motor in the house cycles.

Partial-home vs. whole-home coverage

A smaller generator, in the 7kW to 12kW range, can cover essential loads only: HVAC, refrigerator, selected outlets, and lighting. The installation uses a transfer switch that selects which circuits carry generator power. Everything not on the selected circuits stays off during an outage.

A whole-home generator powers every circuit in the house as if nothing happened. The transfer switch (automatic, meaning you do not have to throw it manually) senses the utility outage and transfers your load to the generator within seconds.

For homes in Weddington, Concord, and similar suburban areas with municipal natural gas, a whole-home system with a 20kW Generac or Kohler unit is a very common choice. The generator runs on gas from the street and never runs out of fuel.

Propane vs. natural gas

If your home has natural gas service from Piedmont Natural Gas or another local utility, that is the simplest fuel source. The generator taps the existing line (with a properly sized gas meter if needed) and runs indefinitely as long as the utility supply is up.

The detail most installs get wrong is the gas line sizing. A 20kW generator at full load burns roughly 300 to 350 cubic feet of natural gas per hour, which is around 300,000 BTU per hour. To feed that, the unit needs a dedicated 1-inch gas line in most runs, and the regulator at the meter has to deliver the right pressure under load. If the line is undersized or shared with the furnace and water heater, the generator starves for fuel and trips out the moment the HVAC adds load. We spec the line for the worst-case draw, not the average, and coordinate any meter or regulator upgrade with Piedmont Natural Gas before the install date so the pressure is there when the generator needs it.

If you are on propane already for cooking or heating, running the generator off the existing propane tank works well as long as the tank is large enough. A 20kW generator at full load consumes roughly 3.4 gallons of propane per hour, so a unit running six to eight hours per day across an extended outage will burn 80 to 100 gallons per week. A 500-gallon tank, filled to its usable 80 percent (about 400 gallons), gives you a reasonable minimum for extended outage coverage in a rural NC setting. For homes well outside the Charlotte corridor in Stanly County, a 1,000-gallon tank removes the worry entirely.

If you have neither gas nor propane, propane is usually the better choice over diesel for residential standby use. Diesel tanks require more maintenance, and diesel generators are louder and more expensive to maintain.

The automatic transfer switch

The ATS is what makes a standby generator useful. Without an ATS, you have to manually transfer your load from utility to generator, which means going outside and throwing a switch in the rain or dark. An ATS senses the utility outage automatically and completes the transfer in seconds without any action on your part.

For most residential units the transfer time is 7 to 10 seconds. That is the window from when the utility drops to when the generator has started, come up to speed, and the switch has handed your load over. Most residential installs use an open transition switch, which breaks the connection to the utility before it makes the connection to the generator. That brief gap is what you feel as the few seconds of darkness during a transfer. Closed transition switches, which overlap the two sources for a fraction of a second so there is no interruption, exist but cost more and are reserved for installs where even a momentary blink is a problem.

On larger whole-home jobs, the ATS pairs with a load shedding module. When the generator is running and a big load like the HVAC compressor starts, the module temporarily drops a lower-priority circuit (often a second air conditioner, an electric range, or a dryer) so the generator never exceeds its rated output. This lets a 20kW unit cover a home that would otherwise need 26kW, without ever overloading the generator. The shed circuit comes right back online the moment the surge clears.

The ATS also prevents backfeed onto the utility lines, which is a safety requirement and a legal requirement in NC. We do not install generators without proper ATS isolation from the utility.

The permit and inspection process in NC counties

A standby generator install is a permitted electrical job in North Carolina, and the permit office is local to the county. Stanly County, Union County, and Cabarrus County each run their own permit office with their own submittal forms and inspection scheduling, so the paperwork and timeline differ slightly depending on where the home sits. We pull the electrical permit under our NC license before any work starts, and the ATS portion specifically has to be installed by a licensed electrician for the permit to clear.

The inspection covers the ATS wiring and utility isolation, the grounding and bonding, the gas connection, the generator pad and its clearances, and the breaker or disconnect that ties the generator into the panel. The inspector confirms there is no path for the generator to backfeed the utility lines. Once the electrical inspection passes, the system is permitted and can run live. If the install also requires a gas meter or regulator upgrade, that gets coordinated with Piedmont Natural Gas on a separate track, and we line up the gas work and the electrical inspection so the project is not waiting on one to finish the other.

Generator brands we install and why

We install Generac, Kohler, and Briggs standby units. All three make solid residential generators, and the right choice usually comes down to the size you need, the noise you can live with, and the warranty you want behind it. Generac has the widest range of residential sizes and the largest dealer network in the Charlotte corridor, which matters for parts and service down the road. Kohler runs quieter at comparable sizes, with many units rated in the low-to-mid 60-decibel range at normal operating load, which is roughly the sound of a conversation a few feet away. For a home in Weddington or Concord on a tighter lot near a neighbor, that quieter rating is often the deciding factor.

All three offer mobile link monitoring, which sends a text or app notification to your phone whenever the generator runs, including its weekly self-test cycle, so you know the unit is healthy before an outage ever hits. On the warranty side, the standard coverage is 5 years, with a paid step up to 10-year extended coverage available on most models. For a home that depends on the generator through every storm season, the 10-year option is usually worth it. We walk through the trade-offs on a load review before recommending a specific unit, because the best brand is the one that fits your load, your lot, and how long you plan to stay in the house.

If you are ready to talk through generator options for your home in Union County, Stanly County, or the Charlotte metro, call 310 Construction at (704) 575-9463 or use the contact page. We do a load review before recommending any equipment.