Why your generator runs everything except the AC
It's the most repeated outage story in Florida: the generator carries the fridge, the lights, the internet — then the AC compressor kicks in and the whole thing bogs down and trips. The generator isn't too small to run your AC. It's too small to start it. Those are wildly different numbers, and the gap between them is exactly what a soft starter closes.
Up front: we don't sell generators and never will. This guide exists because soft starters — which we do stock — are the half of this pairing most people have never heard of.
The two numbers on your data plate
Open your condenser's electrical data plate and find:
- RLA (rated load amps) — what the compressor pulls while running. A typical 3-ton unit: roughly 14–18 A at 240 V, call it ~3.5–4.5 kW with the fan.
- LRA (locked rotor amps) — the startup inrush, typically 5–6× RLA. That same 3-ton unit: 70–90 A, a momentary ~17–22 kW demand.
A generator must survive the LRA moment, not just the RLA cruise. That's why "my AC only needs 4,000 watts" meets reality as "my 8,000-watt generator stalls anyway."
The correction that fixes most bad math
A common misreading: "a soft starter cuts startup current by 30%." No — a good one cuts it to roughly 30% of LRA, sometimes lower. An 85 A LRA becoming ~25–30 A is a ~65–70% reduction. Manufacturers' own ratings are in this range (Micro-Air rates the EasyStart Flex at up to 75% reduction), and the Flex's Bluetooth app lets you watch your actual number instead of trusting a brochure.
Worked example
| Unit | 3-ton single-stage condenser, 16 A RLA / 83 A LRA at 240 V |
| Startup demand, stock | ~83 A × 240 V ≈ 20 kW momentary — stalls anything but a large standby unit |
| Startup with soft starter | ~25–28 A × 240 V ≈ 6–6.7 kW momentary |
| Running demand | ~16 A × 240 V ≈ 3.8 kW + air-handler fan |
| Practical result | A mid-size portable inverter generator with 240 V output and honest ~7 kW surge headroom is now in the game — leaving margin for the fridge and lights |
Illustrative numbers for education — your data plate rules. Margins matter: generators age, heat derates output, and other loads share the bus. Size with headroom, and have a licensed electrician handle any interlock/transfer wiring — backfeeding a panel improperly is how outages become tragedies.
Checklist before you spend anything
- Variable-speed condenser? It already soft-starts; a soft starter adds nothing. (Check your model number with us if unsure.)
- 240 V output on the generator? Central AC needs it; many portables are 120 V only.
- Photograph the data plate. RLA + LRA decide the soft starter model — send it with a question on any product page and we'll size it free.
- Plan the transfer path with a licensed electrician. Interlock or transfer switch — never a "suicide cord."
The honest pitch: a soft starter is one of the few sub-$400 parts that changes what an outage feels like in a Florida summer. It's also unnecessary for plenty of homes — inverter condensers, standby-generator owners with big headroom. Ask us which side you're on before buying: soft starter lineup →