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Five common loads on a 30 amp or 50 amp hookup
At 120 V. The first four are on a 30 amp service and the last is on a 50 amp service, where the worst of the two legs is shown.
| Setup | Total power | Current | % of breaker | Result |
|---|---|---|---|---|
| Air conditioner, converter, fridge, TV and lights | 2,750 W | 22.9 A | 76% | OK |
| Same plus microwave | 3,950 W | 32.9 A | 110% | Over the breaker |
| Same plus coffee maker | 3,650 W | 30.4 A | 101% | Over the breaker |
| No air conditioner: microwave, water heater, converter, fridge, lights | 3,790 W | 31.6 A | 105% | Over the breaker |
| Two air conditioners and a microwave on 50 amp | 5,200 W | 24.2 A | 48% | OK |
A 30 amp service gives 3,600 W, and many people keep long-running loads to about 2,880 W, 80% of that. One air conditioner plus a converter, a fridge and lights already uses about three quarters of it, so a microwave or even a coffee maker pushes it over.
How it is calculated
- Current (A) = total watts ÷ pedestal voltage. Low voltage means more amps for the same watts.
- Breaker share = amps ÷ breaker rating. Over 80% is flagged as near the limit, and over 100% as over the breaker.
- 50 amp service has two 120 V legs. Each leg is checked against 50 amps separately, so the split between L1 and L2 matters. Total capacity is 12,000 W.
- What to switch off picks the biggest loads on the busiest leg until you are under 80%.
It uses running watts only and does not model start-up surges, a built-in energy management system, or campground wiring problems.
30 amp vs 50 amp
- 30 amp is one 120 V circuit at 30 A, or 3,600 W. It runs one air conditioner and a few small loads.
- 50 amp is two 120 V circuits at 50 A each, or up to 12,000 W in total. It runs two air conditioners and cooking at the same time.
- An adapter that plugs a 30 amp cord into a 50 amp outlet does not add capacity. You still have only 30 amps.
Using it anywhere
- Choose a 120 V or a 230 V service. European campsites often offer 6, 10 or 16 amps at 230 V, which is 1,380 to 3,680 W.
- Check the pedestal voltage if you can. A reading well below normal means more current and more heat for the same load.
Why breakers trip
- Several heating appliances at once. Microwaves, kettles, toasters and heaters each use 900 to 1,500 W.
- Air conditioner start-up. It surges for a moment and can trip a nearly full breaker.
- Low campground voltage. Amps rise as voltage falls.
- Thin or long extension cords. They waste power as heat and drop voltage.
- Battery charging. A converter or charger can add 600 to 1,000 W for hours.
Common questions
Can I run an air conditioner and a microwave on a 30 amp RV hookup?
Usually not at the same time. A 13,500 BTU air conditioner draws about 12 to 14 amps, and a microwave about 10 amps. Add a converter, fridge and lights and you reach about 33 amps, which is over the 30 amp breaker. Run the microwave when the air conditioner is off.
How many amps does an RV air conditioner use?
A typical 13,500 BTU rooftop unit uses about 12 to 15 amps at 120 V while running and 2 to 3 times that for a moment when the compressor starts. A soft-start device reduces the start-up surge.
What is the difference between 30 amp and 50 amp RV service?
A 30 amp service has one 120 V line and supplies up to 3,600 W. A 50 amp service has two 120 V lines of 50 amps each and supplies up to 12,000 W in total. The two lines are balanced separately, so spreading loads between them matters.
Why does my breaker trip at the campground?
Common causes are too many heating appliances at once, air conditioner start-up, low campground voltage and long thin extension cords. Check the pedestal voltage, switch off some big loads, and use a heavy-gauge RV-rated cord.
Can I use a 30 amp to 50 amp adapter?
You can connect the plugs, but the adapter does not add capacity. A 30 amp supply is still limited to 30 amps, so keep your loads under the 30 amp limit. Never use a 50 amp rating for a circuit that is protected at 30 amps.
Do I need a surge protector or energy management system?
It is a good idea. A surge protector or energy management system guards against low voltage, miswired pedestals and spikes, which can damage an air conditioner. Choose one rated for your service amperage.
Related calculators
To plan batteries and solar for camping, use the van and RV solar and battery calculator. For the cable between the shore power post and your rig, see the wire gauge and fuse calculator, and for a generator, the generator runtime calculator.