Most of the time the answer is unglamorous: you are asking for more power than the supply will give you. A 30 amp rig has 3,600 watts and an air conditioner plus a water heater plus a microwave is already more than that.
One load people forget to count is the converter — and in winter it can be running harder than you expect, because a cold lithium bank refuses charge until it warms and then takes it all at once. If you have recently upgraded to a lithium house bank and fitted a charger to match it, a bank being refilled at 50 amps is drawing real power at the pedestal while it does so — and it starts the moment you plug in, which is why the trip so often happens on arrival. An 80 amp converter draws around 1,300W on its own, out of the 3,600W a 30 amp hookup provides; sizing a converter to your service is the fix.
The first job is not fixing anything. It is working out which breaker is tripping, because a pedestal breaker, your rig’s main and an individual circuit breaker each point at a different problem.
Start here
| What you see | Likely cause | What to do | Who |
|---|---|---|---|
| Trips only when several appliances run together | Total load exceeds the supply | Shed load. Switch the water heater to propane, run one heavy appliance at a time | Easy |
| Trips the moment the air conditioner starts | Compressor startup surge on top of existing load | Turn other loads off, start the A/C first, then add loads back | Easy |
| Pedestal breaker trips, rig breakers do not | Drawing more than the post supplies, or a pedestal problem | Check your service matches the post. Try a different pedestal | Easy |
| One circuit trips, always the same one | Fault or overload on that circuit | Unplug everything on it, reset, add items back one at a time | Moderate |
| Trips instantly, even with everything unplugged | Short circuit in the wiring | Stop. Do not keep resetting | Technician |
| Trips in wet weather or near the water heater | Moisture reaching a connection, or a failing element | Isolate that circuit and have it inspected | Technician |
| Plug, cord end or receptacle is warm | Loose or corroded connection, resistance heating | Stop using it. This is a fire risk | Technician |
| Power stops but nothing has physically tripped | EMS disconnecting on a voltage or wiring fault | Read the error code on the unit | Easy |
Which breaker is actually tripping?
This single question narrows the problem more than anything else, and it is frequently skipped.
The pedestal breaker sits on the campground post. If this is the one going, your rig is drawing more than the post will supply, or the post itself has a problem. Notably, this one trips without anything inside your rig moving.
Your rig’s main breaker is in the distribution panel, usually the largest one, marked 30 or 50. If this trips, total draw across the whole coach is too high.
An individual circuit breaker protects one circuit — the air conditioner, the outlets on one side, the microwave. If the same one trips repeatedly, the problem is specific and findable.
Go and look before you theorise. On a 50 amp rig, also note which leg the tripping circuit is on, because the two legs are independent and one can be loaded while the other is nearly idle.
Working through it
Diagnostic sequence
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Note exactly what was running
Air conditioner, water heater on electric, microwave, kettle, space heater. Write it down. The combination is usually the answer.
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Turn everything off, then reset once
If it holds with no load, you have an overload rather than a fault. If it trips again with nothing running, you have a fault — stop here and read the last section.
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Add appliances back one at a time
Wait a minute between each. The one that trips it either is faulty, or is the one that took you over the limit — which of those it is depends on how much was already running.
-
Try a different pedestal if you can
If the problem follows you to another post, it is your rig. If it stays behind, it was the post. This is the single most useful test available to you and it costs nothing.
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Check the cord and connections
Look at the plug pins for discoloration or pitting, and feel the plug body after a few minutes under load. Warm is a problem. Hot is a stop.
The load arithmetic, briefly
If you have a 30 amp rig, you have 3,600 watts. That is less than it sounds.
Rooftop air conditioner Electric water heater Microwave
Nothing unusual in that list, and you are already over. This is the entire explanation for the majority of tripping breakers on 30 amp rigs, and it is why the fix is a habit rather than a repair: run the water heater on propane, or turn it off before using the microwave.
To confirm that load is your cause rather than a fault, put your own appliances into the RV amp draw calculator — it separates the running total from the compressor start-up spike, which is the difference between the first and second rows of the table above.
Startup surge makes it worse than the figures suggest. An air conditioner compressor draws well above its running figure for a moment as it starts, so a rig sitting comfortably at 3,000 watts can still trip when the compressor kicks in.
If you are unsure which service you have, or why 50 amp is more than three times 30 amp rather than 67% more, that is covered in 30 amp vs 50 amp RV.
When it is not a breaker at all
Worth separating out, because it produces the same symptom and a completely different fix.
If your power stops but nothing has physically moved to the off position, your breaker has not tripped. Something upstream has cut the supply — and if you have an EMS, that is almost certainly what did it.
An EMS disconnects on low voltage, high voltage, open ground, open neutral or reverse polarity. From inside the rig it feels exactly like a breaker trip. The difference is that the unit will be showing an error code explaining why — and every code is listed here — and that resetting a breaker will achieve nothing because no breaker tripped.
This is also the failure mode people misdiagnose as a faulty surge protector. It usually is not faulty. It is refusing to pass power it considers dangerous, which is what you bought it for. The distinction between a basic surge protector and a unit that does this is covered in EMS vs surge protector.
Genuine faults, in likelihood order
If the breaker trips with nothing running, you are past load management.
Failing water heater element. A common one. Elements fail to ground as they age, and the trip often correlates with the heater cycling on. Isolating that circuit and seeing whether the problem disappears is a good test.
Moisture in a connection. Trips that appear in rain or after washing the rig point here. Exterior receptacles and the shore inlet are the usual locations.
A damaged or undersized extension cord. Resistance in a poor cord produces heat and voltage drop. A coiled cord under load sheds its heat less well than one laid out straight; the voltage it loses is set by its length either way, and our extension cord calculator works out how much, shore cord included.
A worn shore power plug or inlet. Look for pitted, blackened or discolored pins. This is resistance heating and it gets worse, not better.
An ageing breaker. Breakers weaken with repeated tripping and eventually trip below their rating. Suspect this only after ruling out everything above.
A short circuit. Instant tripping every time, regardless of load. Stop.
Preventing the common case
- Know your total. Thirty amp is 3,600 watts, fifty amp is 12,000 across two legs.
- Run the water heater on propane when on shore power, or switch it off before using another heavy appliance.
- Start the air conditioner before other large loads, not after.
- On 50 amp, spread heavy appliances across both legs rather than loading one.
- Use a properly rated RV extension cord, fully unwound, and keep it short.
- Inspect the shore plug pins a couple of times a season for discoloration.
- Fit an EMS. It will not stop an overload, but it removes the pedestal-fault category of problem entirely — see the best RV surge protectors.
When to stop and call someone
Not everything here is a DIY job, and the line is clear:
- Instant tripping with no load connected
- Any burning smell, scorch marks, or discolored plastic
- A warm or hot plug, cord end or receptacle
- Tripping that started after water got somewhere
- Anything requiring the distribution panel to be opened, unless you are qualified
Shore power is 120V at up to 50 amps. It is entirely capable of killing someone and of burning a rig to the ground. Diagnosing by elimination from outside the panel is sensible. Working inside it is not, unless that is your trade.
Related guides
- 30 amp vs 50 amp RV — how much power you actually have, and what will run on it.
- EMS vs surge protector — why an EMS cuts power, and why that is not a fault.
- RV surge protector error codes — what the unit is telling you when it cuts power.
- Progressive vs Power Watchdog — if you are buying an EMS to remove the pedestal-fault category entirely.
- Do I need a surge protector? — including whether your rig already has protection built in.
- Best RV surge protectors — eight units compared for 30 and 50 amp service.
Questions worth answering
Is it safe to just keep resetting the breaker?
Once, to see whether it holds, is reasonable. Repeatedly is not. A breaker is a safety device and each trip means it detected something it considered dangerous. Resetting the same breaker over and over without finding out why is how an overheating connection becomes a fire.
My breaker trips as soon as the air conditioner starts. Why?
Compressor startup draws far more current than running does, briefly. If you are already close to your limit, that momentary spike is what pushes you over. Turn other loads off, start the air conditioner first, then bring things back on one at a time.
The pedestal breaker trips but my RV breakers do not. What does that mean?
That usually points at total draw rather than a fault in one circuit. Your rig is pulling more than the pedestal will supply — common when a 50 amp rig is on a 30 amp post, or when a 30 amp rig runs several heavy appliances together.
Could my surge protector be causing this?
An EMS disconnecting is not the same thing as a breaker tripping, though it looks identical from inside. If power stops and nothing has physically moved to the off position, your EMS has almost certainly cut the supply because of a voltage or wiring problem at the post.
Why does it only trip in hot weather?
Two reasons stack up. Your air conditioner runs more, so your total draw is higher, and campground voltage sags under everyone else's air conditioning, which makes motors draw more current still. Both push you toward the limit at the same time.
Can a bad extension cord trip a breaker?
Yes. An undersized or damaged cord adds resistance, drops voltage and heats up. Use a properly rated RV extension cord, keep it as short as the situation allows, and unwind it fully rather than leaving it coiled.