Cummins QuietConnect RS20AC 20kW with 200A ATS vs Generac Guardian 20kW (7039)
Both units carry the same best-fuel running rating: 20,000 W. The Cummins QuietConnect RS20AC 20kW with 200A ATS is the quieter of the two (65 dBA vs 67 dBA — though manufacturers measure noise at different loads and distances).
| Cummins QuietConnect RS20AC 20kW with 200A ATS | Generac Guardian 20kW (7039) | |
|---|---|---|
| Type | home-standby | home-standby |
| Fuel | natural-gas, propane | natural-gas, propane |
| Running watts (gas / LP for standby) | 20000 W | 20000 W |
| Running watts (propane) | 20000 W | 20000 W |
| Running watts (natural gas) | 18000 W | 18000 W |
| Noise level | 65 dBA | 67 dBA |
| Output voltage | 120/240V | 120/240V |
| Automatic transfer switch included | Yes | Yes |
| Main-line circuit breaker | 100 A | 90 A |
| Start type | automatic | automatic |
| Engine | Cummins QSJ999G | Generac G-Force 1000 |
| Engine displacement | 999 cc | 999 cc |
| NG use at half load | 172 ft³/h | 204 ft³/h |
| Propane use at half load | 1.81 gal/h | 2.37 gal/h |
| Weight | 596 lb | 448 lb |
| Warranty | 5 yr | 5 yr |
Frequently asked questions
Which costs less to run, the Cummins QuietConnect RS20AC 20kW with 200A ATS or the Generac Guardian 20kW (7039)?
Estimated fuel for 24 hours at about 50% load: $62 on natural gas for the Cummins QuietConnect RS20AC 20kW with 200A ATS vs $73 on natural gas for the Generac Guardian 20kW (7039), at national average prices. These are spec-sheet-derived estimates — the assumptions are on the methodology page, and different fuels make this a cost comparison, not an efficiency ranking.
Where do these specifications come from?
Every record on BackupAtlas is hand-curated from manufacturer documentation and spec sheets, and each generator page links to its source document.