Why your generator runs everything except the AC
Your generator can run your AC — it just can't start it. It's the most repeated outage story in Florida: the generator carries the fridge, the lights, the internet, then the compressor kicks in and the whole thing bogs down and trips. Starting a compressor takes far more power than running it, and closing that gap is exactly what a soft starter does.
Up front: we don't sell generators. This guide is about soft starters — 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 a real ~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 for you.
- Plan the transfer path with a licensed electrician. Interlock or transfer switch — never a "suicide cord."
The straight answer: 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 →