50 amp generators: what the outlet does and does not tell you
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Quick answer
A "50 amp generator" has a 120/240 V, 50 amp NEMA 14-50R outlet. A 50 amp circuit at 240 V can carry up to 12,000 watts (50 x 240), but only if the generator can make that much. Generac's GP15500EFI and GP18000EFI each have a 14-50R behind a 50 amp breaker, with 15,500 and 18,000 running watts. Champion's 11,000 watt dual fuel inverter also has a 14-50R, but its 9,000 running watts on gasoline work out to about 37.5 amps at 240 V. Size by running watts, not by the outlet.
Amps, volts and watts on a 14-50R
Watts equal volts times amps. Generac's spec sheets list the 14-50R as a 120/240 V, 50 amp receptacle, protected by a 120/240 V, 50 amp two-pole breaker. That gives a ceiling of:
- 50 A x 240 V = 12,000 W through that one outlet.
Below that ceiling, the generator's own output decides what you get. A unit rated 9,000 running watts can deliver only about 37.5 A at 240 V (9,000 / 240), even through a 50 amp outlet. Above it, a bigger generator still sends no more than 50 A through the 14-50R, though it may power other outlets at the same time.
Three generators with 50 amp outlets
| Champion 201417 | Generac GP15500EFI | Generac GP18000EFI | |
|---|---|---|---|
| Running / starting watts | 9,000 / 11,000 (gasoline), 8,100 / 11,000 (propane) | 15,500 / 19,300 | 18,000 / 22,500 |
| Rated amps at 240 V | About 37.5 (from 9,000 W) | 64.5 | 75 |
| 240 V outlets | 14-50R, L14-30R | 14-50R, L14-30R | 14-50R, L14-30R |
| Fuel | Gasoline or propane, inverter | Gasoline, EFI | Gasoline, EFI |
| Run time at 50% load | See 1/4-load figures: 15 h gas, 8 h propane | 11 h on 14.2 gal | 9 h on 14.2 gal |
| Noise | 64 dBA | Not listed | Not listed |
| Weight | 205.1 lb | 420 lb | 439.2 lb (49-state), 442.8 lb (50-state) |
| CO protection | CO Shield | COsense | COsense |
Generac lists TruePower, under 5% total harmonic distortion, on both EFI models for sensitive electronics.
Which one fits
- Essentials plus 240 V loads. Champion's 9,000 running watts on gasoline, or 8,100 on propane, can feed 240 V circuits through a transfer switch, at less than half the weight of either Generac.
- Most of the house. Generac says that when paired with a manual transfer switch, the GP15500EFI is powerful enough to provide whole home backup. At 420 pounds, it needs a permanent spot or a crew to move.
- The biggest loads. The GP18000EFI adds 2,500 running watts over the GP15500EFI but runs 9 hours at 50% load against 11 on the same 14.2 gallon tank.
Connecting a 50 amp generator to the house
A 14-50R output can feed a 50 amp power inlet and a transfer switch or interlock. NFPA says that if you must connect a generator to house wiring, a qualified electrician should install a properly rated transfer switch to the National Electrical Code. Two details to give your electrician:
- Neutral bonding. Generac's spec sheets list the GP15500EFI and GP18000EFI neutral as bonded to the frame. How that interacts with your transfer switch is a code question for the electrician.
- Breaker sizes. The 14-50R sits behind a 50 amp breaker and the L14-30R behind a 30 amp breaker. Match the cord and inlet to the outlet you use.
Fuel planning
Big generators burn fuel fast. Generac lists 9 to 11 hours at 50% load from 14.2 gallons on its EFI pair. Champion lists 15 hours on gasoline and 8 hours on a 20 pound propane tank at quarter load. Running in blocks, to cool the fridge, pump water and heat water, then shutting off, stretches any supply. Store fuel in containers made for it, outside living areas, as NFPA advises.
What to look for when you buy
11,000 watt dual fuel inverter with 14-50R (example: Champion 201417)
Best for: 240 V essentials on gasoline or propane, at the lightest weight here
Champion lists 9,000 running watts on gasoline and 8,100 on propane, 14-50R and L14-30R outlets, 64 dBA, CO Shield and PGMA G300-2023.
Watch out: About 37.5 amps at 240 V, so the 50 amp outlet is not fully used.
See options on Amazon (opens Amazon in a new tab)15,500 watt EFI portable (example: Generac GP15500EFI)
Best for: Whole-home backup through a manual transfer switch
Generac lists 15,500 running and 19,300 starting watts, 64.5 A at 240 V, a 14-50R behind a 50 A breaker, 11 hours at 50% load, TruePower under 5% THD and COsense.
Watch out: 420 pounds. Gasoline only.
See options on Amazon (opens Amazon in a new tab)50 amp generator cord and power inlet
Best for: Feeding a transfer switch from a 14-50R outlet
Generac lists the 14-50R as a 120/240 V, 50 amp receptacle, so the cord and inlet must be rated for 50 amps at 120/240 V.
Watch out: Have a qualified electrician install the inlet and transfer switch.
See options on Amazon (opens Amazon in a new tab)Questions people ask
- How many watts is a 50 amp generator?
- A 50 amp, 240 V outlet can carry up to 12,000 watts. The generator's running watts set what you actually get, from about 9,000 W on Champion's 201417 to 18,000 W on Generac's GP18000EFI.
- What outlet does a 50 amp generator have?
- A NEMA 14-50R, a 120/240 V, 50 amp receptacle. Generac's EFI models protect it with a 50 amp two-pole breaker.
- Can a 50 amp generator power a whole house?
- A large one can carry much of it. Generac says the GP15500EFI with a manual transfer switch is powerful enough for whole home backup.
- Do I need a transfer switch for a 50 amp generator?
- To feed house wiring, yes. NFPA says a qualified electrician should install a properly rated transfer switch to the National Electrical Code.
Sources
- GP15500EFI Spec Sheet (7705-0), Generac
- GP18000EFI Spec Sheet (7706-0 / 8917-0), Generac
- GP15500EFI Portable Generator, Generac
- 11,000W Electric Start Dual Fuel Inverter with CO Shield (201417), Champion Power Equipment
- Generator Safety tip sheet, National Fire Protection Association
- CPSC Warns of Generator, Carbon Monoxide and Fire Hazards Ahead of Hurricane Season, U.S. Consumer Product Safety Commission