How to run electric heat safely without tripping breakers (or cooking an outlet)

 

Electric heat is one of the fastest ways to make a boat cabin or RV feel comfortable. It’s also one of the easiest ways to overload a shore-power setup if you don’t think about the electrical load first.

Most boat and RV owners aren’t electricians, and they shouldn’t have to be. This page explains “power budget” in plain English so you can make smart decisions, avoid nuisance breaker trips, and reduce the risk of overheated cords and outlets.

Why breakers trip in boats and RVs (even when “nothing changed”)

In a house, you may have lots of separate circuits and plenty of capacity. In boats and RVs, the electrical system is usually more limited, and multiple outlets often share the same breaker.

So you can plug a heater into an outlet and it works, but that does not mean the circuit has extra capacity left. If something else is on that circuit, you might be closer to the limit than you think.

Also, the weak link is not always the breaker. Loose connections, tired outlets, worn shore cords, cheap adapters, and undersized extension cords can heat up under load.

What “power budget” means

Think of shore power like a fixed-size budget. Every appliance you turn on spends part of it.  When you spend too much, one of two things happens:

·        Best case: the breaker trips.

·        Worse case: cords, outlets, adapters, or connections heat up from overload or poor contact.

 

The goal is to run your loads with breathing room.

The simple math that actually helps

Your cabin heater has two settings:

·        Low: 5.8 amps

·        High: 11.5 amps

Those two numbers tell you almost everything you need to know. A typical 15-amp circuit does not have much extra room once you’re running 11.5 amps. It only takes one more “normal” item to push things over the edge.

Common “surprise loads” that push you over the limit

These are the usual suspects that can share a circuit with the outlet you picked:

·        Coffee maker

·        Microwave

·        Toaster

·        Hair dryer

·        Electric griddle

·        Portable dehumidifier

·        Battery charger

·        Another space heater

Individually, these might seem harmless. Combined with a heater on High, they can exceed the circuit capacity quickly.

Practical rules that keep you out of trouble

1) Treat High as a supervised setting

On boats and RVs, High (11.5A) can challenge electrical systems. Use it when you’re awake, present, and able to monitor what else is running. For unattended use, Low (5.8A) is the safer choice.

2) Assume multiple outlets share the same breaker

If you don’t know which outlets are tied together, assume they might be. “Different outlet” does not always mean “different circuit.”

3) Leave a margin

Running at the edge is when problems show up, especially in cold weather when a heater runs longer. A little margin reduces heat buildup in cords and outlets.

4) Watch for warning signs

Switch to Low and reduce other loads if you notice:

·        Breakers tripping

·        Flickering lights

·        A plug, adapter, or outlet that feels hot

·        A “hot plastic” smell

·        Discoloration at the outlet face

If anything feels excessively hot, unplug the heater and have the electrical system inspected by a qualified marine or RV technician.

Quick “Power Budget” examples (real world)

Example A: 15A circuit in an RV

·        Heater on High: remember this is 11.5 amps by itself

·        Coffee maker: often enough to trip the breaker on many setups

Result: nuisance trips, or worse, overheated plugs if the connection is weak.

Example B: Heater on Low with normal background loads

·        Heater on Low: 5.8 amps

·        A few small loads (lights, phone chargers, TV): typically manageable

Result: more stable operation and less stress on the circuit.

A simple “before you run High” checklist

·        Turn off other high-draw appliances (coffee maker, microwave, toaster, hair dryer, etc.).

·        Avoid questionable adapters and undersized extension cords.

·        After a few minutes, feel the plug and outlet. Warm is normal. Hot is not.

·        If anything seems off, switch to Low and reduce other loads.

Important: where this cabin heater should and should not be used

This cabin heater is intended for indoor, dry-location use.

·        Do not use outdoors.

·        Not water resistant. Do not allow it to be sprayed, soaked, or immersed.

·        Do not use in tight enclosed spaces where airflow can be restricted.

·        Do not use in hazardous locations or areas that may contain flammable fumes.

 

If you need heat for a bilge, engine room, RV underbelly, wet bay, or similar compartment environment, we offer purpose-built Boat Bilge and RV compartment heaters designed specifically for those applications.

Why we’re blunt about this

We’d show you the limits up front than have you learn the hard way what an overloaded circuit can do. Run with margin, and your system will be more reliable.

If you’re unsure about your shore-power setup, a quick conversation with a marine/RV technician is money well spent.

Power Budget Tip: High heat draws 11.5 amps. On many boats and RVs, that can nearly max out a typical 15-amp circuit. Use High only when supervised and keep other high-draw appliances off. For unattended use, run Low (5.8 amps).