For this storm-outage scenario, plan around 1,325 W of continuous running capacity and 1,860 W of AC starting capacity. These targets cover the modeled 1/3 HP sump pump, refrigerator and lighting loads. They are screening values, not a product-specific compatibility result.
The decisive constraint is motor startup. The scheduled running load reaches 1,060 W, while the modeled refrigerator start raises total demand to 1,860 W. Before choosing a generator, verify that its continuous and surge ratings meet these targets. Also confirm that its voltage, frequency and receptacles match your actual pump and refrigerator; those electrical details are not supplied in this scenario.
Loads and priorities in this outage plan
The default plan includes:
- A 1/3 HP sump pump as the critical load. It cannot be shed in this scenario.
- A standard top-freezer refrigerator as another important household load.
- Four LED bulbs as secondary lighting.
- Two phone chargers as secondary loads.
At the scheduled peak, the operating loads are Sump pump 800 W, Refrigerator 200 W, LED light bulb ×4 60 W, totaling 1,060 W. The phone chargers are included in the plan but are not operating at that particular scheduled peak. If every listed AC load operated at once, the running total would be 1,090 W. No DC loads are included.
Protect the sump-pump capacity first. If the actual generator has limited margin, reduce or reschedule the lights and phone charging. Whether the refrigerator must remain available is an outage-priority decision, but removing it changes this scenario and requires a new calculation. Do not remove the pump merely to make a smaller generator appear suitable.
Why startup sets the larger requirement
Running and starting watts represent different demands:
- Running watts are the power equipment needs while operating normally.
- Starting watts include the brief additional demand when a motor starts.
In the modeled event, 1,060 W is already operating when Refrigerator adds 800 W while starting. That produces the total 1,860 W AC starting estimate.
For continuous operation, the engine divides the 1,060 W scheduled envelope by this scenario's 0.80 planning factor, producing the 1,325 W running-capacity target. This headroom policy is specific to the bound scenario; it is not a universal generator-sizing rule.
The model assumes one motor starts at a time. It does not establish that a generator rated for 1,860 W can handle the pump and refrigerator starting simultaneously. Surge duration, automatic restart timing, waveform tolerance and voltage drop could change actual starting performance.
Storm duty changes energy use, not this demand estimate
Generator capacity is measured in watts (W). Energy accumulated over time is measured in watt-hours (Wh) or kilowatt-hours (kWh). The default schedule uses approximately 4.55 kWh and 9.1 kWh over 48 h. These energy estimates do not replace the running- and starting-watt targets, and they do not predict fuel use or generator runtime.
The registered cases illustrate how different outage schedules and inputs can change energy use:
| Registered case | Energy per day | Energy over 48 hours | Displayed running target | Displayed starting estimate |
|---|---|---|---|---|
| Lean | 4.44 kWh | 8.89 kWh over 48 h | 1,325 W | 1,860 W |
| Base | 4.55 kWh | 9.1 kWh over 48 h | 1,325 W | 1,860 W |
| High-demand | 6.78 kWh | 13.55 kWh over 48 h | 1,325 W | 1,860 W |
Lean, base and high-demand are separately registered cases in which several inputs may differ. We therefore treat them as case comparisons, not as a controlled test that changes only pump duty. All three retain the same displayed demand targets even though their energy totals differ.
The pump schedule represents an assumed storm-inflow and cycling pattern. It is not a flood forecast or a measurement of your pump. The modeled reference day is repeated across the 48-hour horizon as a planning simplification, and the schedule is not validated electrical dispatch.
What to verify before choosing or connecting a generator
Use the calculated targets as a screening step, then check the actual equipment:
- Read the pump nameplate. Look for voltage, current in amperes, frequency in hertz, horsepower and any listed running or startup information. The label may be on the pump body, power-cord tag or control documentation.
- Check the refrigerator label or model documentation. Replace the scenario defaults when matching model-specific running or starting information is available.
- Read both generator ratings. Compare the continuous or running rating with 1,325 W, and compare the surge or starting rating with 1,860 W. A surge rating alone does not establish adequate continuous capacity.
- Confirm electrical compatibility. Match the equipment voltage and frequency to the generator's labeled output, and confirm that the required receptacles are available. This page cannot determine compatibility because those details are unknown.
- Account for automatic cycling. The sump pump and refrigerator can restart without manual scheduling. This estimate covers one modeled motor start at a time, not every coincident-start sequence.
- Follow equipment instructions. Permanent generator connections, transfer equipment and household wiring are outside this calculation. Use a qualified electrician for permanent connections.
If a value is unknown, do not enter zero or treat the missing value as a pass. Keep it marked unknown until you find the nameplate, obtain documentation for the matching model or get the value from the manufacturer.
No candidate generator rating was entered, so the engine cannot issue a continuous-capacity or startup pass/fail result. The displayed result of no unserved energy also does not prove compatibility because the scenario has no generator running or surge limit to enforce.
Check and enter your equipment ratings
Start with the pump's actual nameplate or matching model documentation, and replace the planning defaults when better information is available. Do the same for the refrigerator. Then enter the candidate generator's continuous and surge ratings. Keep the result unknown until both generator ratings and the required electrical compatibility have been checked.
For more detail, use our guides to review sump-pump watts, refrigerator watts and the difference between running and starting power.