Originally Posted by jtownstumpjumper
Okay, I think I follow your comment, but for someone who's installed a second on/off switch in the control panel and it's OFF then it shouldn't matter that the on/off switch outside is ON, correct?.....one shouldn't have to worry about the water heater when you hook to shore power because it shouldn't come on....is this correct thinking?
That would be correct, as the ones who have made this mod have stated.
I am going to point out one thing for maybe newer inexperienced members (reading this topic later), that really doesn't have anything to do with the mod topic at hand, but the electric heating element on the Suburban water heaters in general.
When the electric heating element is energized (the thermostat calls for heat), it will draw about 12 amps of electrical. If you are on a 30 amp power supply, then you will be limited as to what other electrical things can be used at the same time, as you will need to keep it around the 18 amp mark to keep from possibly overloading circuits and/or tripping breaker(s). 18 + 12 = 30 amps. Another way to think of it is, the electric heating element will use 40% of your available power, when it's energized and heating the water.
You will have to practice energy management, and learn what can be on (and thus what has to be off) at the same time to keep from overloading the power supply/breakers. If the breaker(s) trip, then you know that you are overloading something....but I always hate to put blind faith in the breakers tripping.....thus it's good to know in your head what you should/shouldn't use at the same time. Your air conditioner, microwave, and electric water heater element are 3 of your biggest factory installed RV electrical usage items. Most times, all 3 of these cannot be on at exactly the same time, without overloading a 30 amp supply.
Mark Polk has a great article here that really explains the 30 amp power supplies near the bottom:
Good thing is, with this mod, you can easily turn off the electric heating element without going outside....... when you need to turn it off (or make sure the heating element doesn't come on while other things are in use) ...... so you can use other electrical things and stay within your 30ish amp thresh hold.