What can a 30 amp generator hookup run?
A 30 A generator inlet (usually an L14-30 on 240 V, sometimes a TT-30 on 120 V) is the common size for portable generators. The cable and breaker set the ceiling; the generator's own rating may be lower.
The ceiling, from amps times volts
| Circuit | Maximum (A × V) | Continuous (80%) |
|---|---|---|
| 30 A at 120 V (one leg) | 3,600 W | 2,880 W |
| 30 A at 240 V (both legs) | 7,200 W | 5,760 W |
Continuous loads are kept to 80% of the breaker rating (NEC 210.19(A) and 215.2(A) for loads over 3 hours). The generator itself must also be rated for the watts you draw. A 240 V circuit feeds two 120 V legs that must be balanced when you split loads between them.
Typical appliances against that ceiling
| Appliance | Typical running | Typical start-up | On 30 A, 120 V only | On 30 A, 240 V |
|---|---|---|---|---|
| Refrigerator (full size) | 150 W | 1,200 W | yes | yes |
| Chest freezer | 100 W | 800 W | yes | yes |
| Microwave (1,000 W cooking) | 1,500 W | 1,500 W | yes | yes |
| Coffee maker | 1,000 W | 1,000 W | yes | yes |
| Electric kettle | 1,500 W | 1,500 W | yes | yes |
| Electric range or oven | 3,000 W | 3,000 W | needs 240 V | yes |
| Gas furnace blower fan | 500 W | 1,500 W | yes | yes |
| Window AC (8,000 BTU) | 700 W | 2,000 W | yes | yes |
| Central AC (3 ton) | 3,500 W | 9,000 W | needs 240 V | runs, but start-up too high |
| Electric space heater | 1,500 W | 1,500 W | yes | yes |
| Box or ceiling fan | 60 W | 60 W | yes | yes |
| Electric blanket | 100 W | 100 W | yes | yes |
| Sump pump (1/3 HP) | 800 W | 2,400 W | yes | yes |
| Well pump (1/2 HP) | 1,000 W | 3,000 W | needs 240 V | yes |
| CPAP (humidifier off) | 40 W | 40 W | yes | yes |
| CPAP with heated humidifier | 90 W | 90 W | yes | yes |
| Oxygen concentrator | 300 W | 600 W | yes | yes |
| Wi-Fi router and modem | 20 W | 20 W | yes | yes |
| Satellite internet dish | 75 W | 75 W | yes | yes |
| Laptop | 60 W | 60 W | yes | yes |
| Desktop PC and monitor | 250 W | 250 W | yes | yes |
| TV (55 inch LED) | 100 W | 100 W | yes | yes |
| Phone charging (4 phones) | 20 W | 20 W | yes | yes |
| LED lights (5 bulbs) | 45 W | 45 W | yes | yes |
| Garage door opener | 500 W | 1,000 W | yes | yes |
| Aquarium pump and heater | 50 W | 50 W | yes | yes |
| Washing machine | 500 W | 1,500 W | yes | yes |
All appliance numbers are typical values from our own table, not measurements of your device; the label wins. "Yes" means both the running and start-up figure fit under the maximum, and the running figure fits under the continuous limit.
Step-start: add the loads one at a time
Motors (fridge, sump pump, furnace fan, AC) draw several times their running watts for a second or two when they start. Start the biggest one first, then add the rest, and keep the total running load under the continuous limit. Example on a 30 A, 120 V circuit: fridge, sump pump, furnace fan, LED lights and router run together at 1,515 W. If the sump pump starts while the others run, the peak is about 3,115 W (running total plus the largest extra start-up draw). Limit: 3,600 W peak, 2,880 W continuous. That fits.
240 V versus 120 V
Well pumps, central AC and ranges are 240 V loads and need a 240 V inlet and a matching generator outlet. Many 120 V appliances can be moved between the two legs of the panel, so the usable total on 240 V is about twice the 120 V figure only when the loads split evenly.
Safety
Never feed a panel through a dryer outlet or a "suicide cord". A generator inlet must be wired with an interlock or transfer switch, and the work needs a licensed electrician and a permit where required. Local amendments apply. Run generators outdoors, well away from windows.
Size a generator for your loads Match the inlet, breaker and cable
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