What Electric Source for New Water Heater?

Bzerull · 07-25-2024, 06:13 AM

I have a 2002 Spirit motor home and am replacing the Atwood water heater, gas only, with a dometic gas/electric 6 gallon model. Since I did not have electric with my old model, what would be a good source (location) to tap into a 120v power supply? I do not have an extra space for an additional circuit breaker in my panel. Also, will the existing 12v on/off switch in the existing panel work with the 12v on the new heater? Thank you for any input you can share.

Morich · 07-25-2024, 08:41 AM

This may take some looking/thinking about how you want to use the RV. There are always tradeoffs to be made and they will often depend on what you feel is more important.
Time, expense, convenience are all questions.

One of the first things I would look at is what restrictions we will have and that can start with what equipment we now have needs for power. With the current power cord and load center main of 30 amps , we need to start with 30 amp as a limit. That means we need to look at what the various items we use now will require and subtract that from the 30 available.
Is there enough spare amps to add a water heater or do we need to have some form of load shedding? How much does the water heater require on 110AC?
Ideal might be that there is enough and we just add a small breaker box somewhere near the existing load center and put another sub breaker there for the water heater!

But some may want to do a bit more work and go for a less complex setup by adding another power cord to plug in at power poles and have an almost totaly seperate system for the water heater alone!
But that also gets back to what current needs the heater will have. Got any specs on the new one?

bigb · 07-25-2024, 09:08 AM

Quote:

Originally Posted by Bzerull

I have a 2002 Spirit motor home and am replacing the Atwood water heater, gas only, with a dometic gas/electric 6 gallon model. Since I did not have electric with my old model, what would be a good source (location) to tap into a 120v power supply? I do not have an extra space for an additional circuit breaker in my panel. Also, will the existing 12v on/off switch in the existing panel work with the 12v on the new heater? Thank you for any input you can share.

How many watts is the element? With standard elements being 1,000 to 1,400 watts it will most likely need a dedicated circuit. (In fact, just for reference, NEC requires any equipment that is fastened in place in a dwelling and uses more than 50% of the circuit must have a dedicated circuit.)

In order to do that without adding another circuit breaker you can share it with another circuit using either a AES (automatic energy selection switch) or just a 3 way switch wired with the common to the circuit breaker and each load on the remaining screws. Either of these two options will allow only one load to run at a time. The AES is nice because it's automatic, and you can choose which load has priority.

I've heard of people doing like Richard mentioned and running a second cord to the pedestal, I guess that works but without going into a lot of detail, as a licensed electrician, I would consider that a questionable installation for several reasons.

Bzerull · 07-25-2024, 09:43 AM

Would it hurt to add another power source down stream of the GFCI breaker outlet? That would make it relatively easy for me. Before i had this motor home I had a travel trailer with the electric/gas water heater on a 30 amp circuit with no problem. I have thought of just plugging into an external supply also, but just don’t really want to do that.

bigb · 07-25-2024, 09:48 AM

Quote:

Originally Posted by Bzerull

Would it hurt to add another power source down stream of the GFCI breaker outlet? That would make it relatively easy for me. Before i had this motor home I had a travel trailer with the electric/gas water heater on a 30 amp circuit with no problem. I have thought of just plugging into an external supply also, but just don’t really want to do that.

Can't answer that without knowing the wattage of the water heater element, the size of the GFCI circuit and what other loads are on that circuit.

bigb · 07-25-2024, 10:17 AM

Putting it another way, it's your RV and you can do as you like but since you came here asking advice I'm assuming you want it safe and reliable and that's what we're attempting to do. If you just plug it into an existing circuit it may or may not work, if you over load the circuit the breaker will trip and you'll end up with no hot water.