Electric heaters

Thank you all for your input. I'll just go and buy another 1500 watt and stay on separate breakers. This forum is worth it's weight in gold. Good people, thank you

Electric heat = end of days! The sky is falling!

j-d wrote:


I learned via another OP that a pair of electric heaters is very taxing on the 30A system, and it often shows up where the flexible shore tie splices into the hard wire of the coach.

By code calculation, two 1500 watt heaters operating simultaneously at 120 volts (and NOTHING else running) would require a 31.25 amp breaker. There is no such thing of course and you'd have to go to the next size up which is 35 amps but the main breaker in the converter panel is 30 amps and is the one in the pedestal. You'll also have the converter drawing a couple of amps or so.

The reason a 30 amp breaker did not trip is probably because of voltage drop and the heaters aren't running at rated wattage. Heater output varies as the square of the voltage. For ex. at 115 volts wattage would be 1378 and at 110 would be 1260. That is for voltage measured right at the heater's terminals inside the unit and the drop would include the heater's cord and all wiring back the the CG main power source. You probably won't get exactly 120 volts at the heater element very often. A voltage of 118 volts at the heater terminals would let you just squeak by and not trip a 30 amp breaker, but that's ignoring any other loads like the converter.

There is the code required 80 percent safety derating actor that is required, but that covers fixed/hardwired loads and the NEC doesn't apply to portable plug-in appliances. Interestingly, here in Canada we are allowed to operate fixed heater circuits at 100 percent of the wire (but the breaker must be derated by 80 percent). We can have 1800 watts on #14 wire (at 120 volts).

The worst thing that could happen is one of the 30 amp breakers will trip if running 2 x 1500 watt heaters. However I'd be concerned about how good the shore power plug to pedestal receptacle connection is. Depending on the floor areas you have and how good the insulation is, two heaters could be running together for hours at a time. If there is resistance in the plug/recept. contact surfaces, you'll get overheating and potentially a meltdown. In a perfect world you should be able to draw 30 amps all day long but pedestals are not perfect and some older ones are really nasty looking and asking for trouble.

A 1500 and a 1000 watt max. heater *might* work (if running continuous) and I don't think I would go more than that to allow for something else to run. Ideally heaters would cycle on/off but they probably won't. We have 1750 watts of permanently installed heaters and it works fine for the approx. 200 sq. ft we have, which is about 9 watts per sq. ft. In comparison, a wood frame bldg., 6 watts/sq/ ft. was a rule of thumb that was typically used here in BC.

Hi Dennis,

For 240 volts yes.

For 120 volts it is not a great idea, but I do know of one. It does have to be hard wired in place, and is quite pricey.

If you plan on using a 1500 watt heaters I would include as part of the plan upgrading the "junk" 120 volt outlets in the RV.

I prefer oil filled heaters and electric heated carpets. I use 1/2 size oil filled that draw about 460 watts.

I've added 2 additional shore power cords--one is 20 amp, the other is 15 and I use them to run additional heaters. I plug them into a "break out box" intended for a 50 amp pedestal.

As Mex suggests, hard wired is a better solution.

Dennis12 wrote:
Does anyone know of a electric heater with more than 1500 watts?

We can run two 1500's in our coach, overnight, if nothing else but the Converter is running. They have to be on two separate circuits, and by that I mean different breakers. I stress that because RV builders are very circuit-stingy. We had an extra slot in our breaker section. Load Center's mounted on the bed pedestal so I used that slot to add a breaker that goes only to an outlet for a bedroom heater.

I learned via another OP that a pair of electric heaters is very taxing on the 30A system, and it often shows up where the flexible shore tie splices into the hard wire of the coach. Fortunately this OP's RV was a Winnebago and was able to pinpoint a possible point of failure. Had him find that box and open it up. Wire nut connections fried! He called the tech to cancel the service call still a couple days out, and tech told him what I repeated above,

I would be tempted to use a hard wired baseboard heater if very high output is desired.

rjxj wrote:
There are 2 circuits in most newer houses, 15 amp and 20 amp.
15 amps x 120 volts = 1800 watts.
20 amps x 120 volts = 2400 watts.
They produce heaters with a max of 1800 watts which could run on a 15 amp circuit but it would be maxed out and could trip the breaker. It would be better if you could run it on a 20 amp circuit.

How many amps is the wiring/circuit that you plan to run it on? If it's 15 amp I would probably lean more to 1500 watts or less. It's one of those things that you may have to try. If returning the item is a hassle that may matter too.

I always placed mine on the open oven door so it might not catch the rig on fire if it goes into melt down as I have had 2 of them do that over the years. Some consider them a temporary solution for heating until a proper heating system can be sized. Some will only use them while awake!!!!

Any breaker should NEVER run more than 80% of it's rating, if run in continuous mode, which is what an electric heater pulls. So a 15 amp breaker circuit should be limited to 12 amps continuous, and a 20 amp breaker to 16 amps continuous.

There are lots of electric heaters that are over 1500 watt but they are hardwired, not portable. Are you looking for a mounted heater like a baseboard heater?

...and use good outlets, not the 99 cent contractor grade ones.

Circuit breakers don't immediately trip when there's an overload. A 15 A breaker can take up to an hour to trip with a 20 A (135%) load. And that's assuming a constant load. If the load is switching on and off, it might never trip.

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