"shortage"? Please expand on what you mean as am unfamiliar with the application of the term.
Lost electrical power in the trailer,does not allow to put fuse in "ON" position.
After emptying the hot water tank could move fuse to "ON" and regained power.
OPEN the AC circuit breaker for the water heater electric heating element.......
Then CLOSE the AC Breaker that tripped (your fuse) so you have power back on.
Then........have an electrician check out what shorted out on water heater and WHY the AC breaker for water heater didn't trip. If you have an electrical short at water heater and you lost ALL AC power to trailer than there is a big problem with that breaker.
The water heater AC breaker should have tripped......that would NOT cause you to lose all AC power
2007 RAM 3500 QC LB SRW 5.9L CTD 48re 4:10 4K in bed 'quiet genny'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
Hit the Road Free & Clear April '07
Ok, here is the real skinny on why what you did worked. The electric element in your water heater probably burned out,just like they do in a stick house if it is electric, and the water acted like a conductor to the metal of the heater causing a dead short. When that happens it can cause any c/b to trip even the one outside your rig. When you drained the water that took away the conductor so to speak to ground allowing you to reset the outside c/b. As some have said turn off the heater ac c/b and refill heater and run it on propane till you can get a new element for the heater. Hope this helps.