38 kW generator
For example, the Generac RG03824, a 38 kW standby generator, delivers 38,000 W with propane. On natural gas, output is about 33,820 W, while other models rate a little differently. Powered by natural gas, the unit supports homes up to 5,000 sq ft that include 3-ton central air.
The installed price of a natural gas 38 kW model begins at $22,300 in Arkansas and rises to $25,400 in Oregon. Labor costs by state come from BLS wages for May 2025.
Would a 38 kW unit meet your home's needs? Choose the size with three questions, including the AC or well pump start.
What a 38 kW generator runs
| Loads running together | Running | Peak at a motor start | Natural gas | Propane |
|---|---|---|---|---|
| Essentials | 4.5 kW | 5.6 kW | runs | runs |
| Essentials and a 1 hp well pump | 6.5 kW | 8.5 kW | runs | runs |
| Essentials and a 2-ton central AC | 7.0 kW | 9.0 kW | runs | runs |
| Essentials and a 3-ton central AC | 8.0 kW | 10.5 kW | runs | runs |
| Essentials and a 4-ton central AC | 9.5 kW | 12.5 kW | runs | runs |
The essentials list includes the furnace blower, router, TV, lights, microwave, a 1/2 hp sump pump, freezer and fridge. For the "runs" figure, your running load stays below 80% of the rating. Coverage also includes the largest motor start.
| Whole house load | Natural gas or propane |
|---|---|
| No central air | up to 5,000 sq ft |
| Central AC, 3 ton | up to 5,000 sq ft |
| Central AC, 4 ton | up to 5,000 sq ft |
Whole house rows follow the NEC 220.83 rules, including 3 VA per sq ft for lights and outlets. Kitchen and laundry circuits and gas heat are also included. Electric ranges, dryers and water heaters are excluded. Review your home.
Hourly fuel use
| Load | Natural gas | Gas cost | Propane | Propane cost |
|---|---|---|---|---|
| 25% | 164 cu ft | $3.59 | 1.75 gal | $4.78 |
| 50% | 255 cu ft | $5.59 | 2.90 gal | $7.92 |
| 75% | 346 cu ft | $7.58 | 4.05 gal | $11.06 |
| 100% | 437 cu ft | $9.58 | 5.20 gal | $14.20 |
Generac's fuel table for the RG03824 gives half and full load figures. Values at 25% and 75% come from readings between those points. These costs are based on EIA US average prices.
Propane tank run time
| Tank | 25% load | 50% load | Full load |
|---|---|---|---|
| 120 gal | 55 h | 33 h | 18 h |
| 250 gal | 114 h | 69 h | 38 h |
| 500 gal | 229 h | 138 h | 77 h |
| 1,000 gal | 457 h | 276 h | 154 h |
Tanks fill to 80%.
Installation price
| Line, 38 kW | Natural gas | Propane | Basis |
|---|---|---|---|
| Generator and transfer switch | $18,500 | $18,500 | estimate, sold through dealers |
| Electrician: switch, wiring, start-up | $4,200 to $7,700 | $4,200 to $7,700 | published install ranges based on a wage set to the US average of $34.37 an hour (BLS) |
| Fuel line | $500 to $2,000 | $800 to $2,500 | The gas line runs from the meter; the propane line runs from the tank. |
| Pad and permit | $300 to $1,200 | $300 to $1,200 | composite pad or slab, local fees |
| Installed | $23,500 to $29,400 | $23,800 to $29,900 | propane leaves out the tank |
Whole house generator cost by state.
Generator sizes: 32 kW model 48 kW model All size options