Technical transparency
Calculator methodology and generator sources
SMG Method 1.0 · Catalog 2026-09-19
SizeMyGenerator produces a homeowner planning class for a residential optional-standby system. It is not a product selection, installation design, code approval, AHJ approval, manufacturer endorsement, or site-specific engineering.
What the calculator checks
The calculator develops an estimated running demand, applies the selected headroom, checks one controlling expected motor or compressor starting event, and then finds the smallest validated catalog class that passes both continuous and starting checks for the selected fuel. A result identifies the tightest check and displays material adjustments.
Running loads
General dwelling loads use the calculator’s documented 2023 NEC optional-dwelling planning implementation. Nameplate-derived volts and amps are treated as apparent power for this screen. Heating and cooling alternatives are evaluated as scenarios rather than all being added together. The result’s expandable load details show what was included, managed, or not included.
Motor and compressor starts
The peak check replaces the selected motor’s running contribution with its starting contribution; it does not count both. Direct nameplate LRA, manufacturer data, or qualified measured values are preferred. When the interface uses a sourced screening estimate, the result labels it as estimated. One controlling start is modeled, so outage-recovery concurrency and equipment-specific voltage response still require professional review.
Location, load management, and soft starts
Elevation and temperature adjustments come from the environmental rule assigned to each validated generator row. Load-management credit is applied only to loads the homeowner marks as controlled by an applicable installed system. Soft-start treatment uses either an explicitly entered post-soft-start current or the stated planning reduction; actual installed performance must be confirmed.
Validated catalog selection
Only active rows in the canonical provenance ledger can reach the runtime selector. Each row identifies its manufacturer configuration, fuel-specific continuous output, the numeric starting-capacity definition used for comparison, environmental rule, source document, and verification date. Rows without adequate primary-source support are suppressed instead of being retained with a warning.
Generator source register
The following recommendation-eligible rows were last verified on 2026-09-19. Ratings shown are for the listed 120/240 V single-phase configuration.
| Class / model | Continuous LP / NG | Starting basis | Source |
|---|---|---|---|
| 26 kW · G007290/G007291Guardian, 120/240 V, single phase, 3,600 RPM | 108.3 A / 93.8 A26 kW LP / 22.5 kW NG | 230 Amanufacturer published LRA at 240V | G007290/G007291current at verification · verified 2026-09-19 |
| 22 kW · RG02224Protector QS, 120/240 V, single phase, 1,800 RPM | 92 A / 92 A22 kW LP / 22 kW NG | 135 Asurge amps at 0.4 PF 30 percent voltage dip | A0005999721Rev. B 04/10/2025 · verified 2026-09-19 |
| 25 kW · RG025Protector, 120/240 V, single phase, 3,600 RPM | 104 A / 104 A25 kW LP / 25 kW NG | 170 Asurge amps at below 0.4 PF 30 percent voltage dip | 0L0037SBY-N03/09/2022 · verified 2026-09-19 |
| 27 kW · RG02724Protector QS, 120/240 V, single phase, 1,800 RPM | 113 A / 104 A27 kW LP / 25 kW NG | 170 Asurge amps at 0.4 PF 30 percent voltage dip | A0005999721Rev. B 04/10/2025 · verified 2026-09-19 |
| 30 kW · RG030Protector, 120/240 V, single phase, 3,600 RPM | 125 A / 125 A30 kW LP / 30 kW NG | 180 Asurge amps at below 0.4 PF 30 percent voltage dip | 0L0037SBY-N03/09/2022 · verified 2026-09-19 |
| 32 kW · RG03224Protector QS, 120/240 V, single phase, 1,800 RPM | 133 A / 133 A32 kW LP / 32 kW NG | 180 Asurge amps at 0.4 PF 30 percent voltage dip | A0005999721Rev. B 04/10/2025 · verified 2026-09-19 |
| 36 kW · RG036Protector, 120/240 V, single phase, 3,600 RPM | 150 A / 150 A36 kW LP / 36 kW NG | 240 Asurge amps at below 0.4 PF 30 percent voltage dip | 0L0037SBY-N03/09/2022 · verified 2026-09-19 |
| 38 kW · RG03824Protector QS, 120/240 V, single phase, 1,800 RPM | 158 A / 158 A38 kW LP / 38 kW NG | 180 Asurge amps at 0.4 PF 30 percent voltage dip | A0005999721Rev. B 04/10/2025 · verified 2026-09-19 |
| 45 kW · RG045Protector, 120/240 V, single phase, 3,600 RPM | 188 A / 188 A45 kW LP / 45 kW NG | 240 Asurge amps at below 0.4 PF 30 percent voltage dip | 0L0037SBY-N03/09/2022 · verified 2026-09-19 |
| 48 kW · RG048Protector, 120/240 V, single phase, 1,800 RPM | 200 A / 200 A48 kW LP / 48 kW NG | 300 Asurge amps at below 0.4 PF 30 percent voltage dip | A0000373704Rev. E 09/25/2020 · verified 2026-09-19 |
| 60 kW · RG060Protector, 120/240 V, single phase, 3,600 RPM | 250 A / 250 A60 kW LP / 60 kW NG | 320 Asurge amps at below 0.4 PF 30 percent voltage dip | 0L0037SBY-N03/09/2022 · verified 2026-09-19 |
| 60 kW · RG060Protector, 120/240 V, single phase, 1,800 RPM | 250 A / 250 A60 kW LP / 60 kW NG | 413 Asurge amps at below 0.4 PF 30 percent voltage dip | A0000373704Rev. E 09/25/2020 · verified 2026-09-19 |
| 80 kW · RG080Protector, 120/240 V, single phase, 1,800 RPM | 312 A / 333 A75 kW LP / 80 kW NG | 600 Asurge amps at below 0.4 PF 30 percent voltage dip | A0000373704Rev. E 09/25/2020 · verified 2026-09-19 |
| 100 kW · RG10090Protector, 120/240 V, single phase, 1,800 RPM | 400 A / 400 A96 kW LP / 96 kW NG | 854 Asurge amps at below 0.4 PF 30 percent voltage dip | A0001454434Rev. J 03/24/2025 · verified 2026-09-19 |
| 130 kW · RG13090Protector, 120/240 V, single phase, 1,800 RPM | 542 A / 542 A130 kW LP / 130 kW NG | 900 Asurge amps at below 0.4 PF 30 percent voltage dip | A0002505135Rev. D 08/30/2024 · verified 2026-09-19 |
| 150 kW · RG15090Protector, 120/240 V, single phase, 1,800 RPM | 558 A / 600 A134 kW LP / 144 kW NG | 900 Asurge amps at below 0.4 PF 30 percent voltage dip | A0002505135Rev. D 08/30/2024 · verified 2026-09-19 |
Major limitations and professional handoff
- Actual 120/240 V panel-leg balance, neutral loading, fuel delivery, transfer equipment, conductor sizing, and local requirements are not designed here.
- Model-specific transient response, voltage/frequency limits, heat-pump defrost and staging, and sensitive-equipment compatibility remain installation checks.
- Final equipment and electrical design should be verified by a qualified electrician or generator professional using the copied result and actual equipment data.
Version history
- Method 1.0
- Initial public reproducible-result contract: running demand, continuous requirement, peak check, tightest check, material adjustments, and load basis.
- Catalog 2026-09-19
- Initial public validated provenance snapshot. Unsupported small air-cooled rows were suppressed; current RG13090 and RG15090 values were reconciled.