probably right, though some previous and other manufacturers put the Fireplace circuit and the Microwave on the same shared circuit, with an automatic 'switch' in between, allowing the fireplace only to operate when the microwave is not, or vice versa.... since both working at the same time on the same circuit might trip the breaker.
some folks asks why this is - why not simply put each on it's own circuit breaker?
the simple answer is that there is sometimes not enough 'room' in the circuit panel for an additional breaker, OR this leg, or 'side' of the incoming 50amp power, cannot handle both circuits operating at the same time, along with everything else on the leg... you might otherwise get 'nuisance' tripping of breakers, and that would be just as aggravating.
they also realize that the fireplace is more of an 'amenity', or ambiance, rather than a need, and therefore put it's priority after other devices...
some older models of RVs might even have a switch that makes you decide 'which' device you want to use, at any given time - such as the rear air conditioner versus the water heater, or microwave, etc... more of a manually way to do the same thing.
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