I have a manufactured home 2003 model. The breaker for hot water tank is tripping & at the breaker box it has 2 single breakers only 1 is tripping ?? Has it been wired wrong ? And what should I do ?
The proper breaker would be a 2-pole common trip breaker and not two 1-pole breakers. Buy a proper breaker in the correct current level (amps rating) for the wiring you have and install it. Usually the heater wiring would be #10 copper protected by a 30-A 2-pole breaker. What size wiring do you have? What is the current rating of the present breakers?
Flip the new breaker on and if it stays on, then you have fixed the problem. The tripped 1-pole breaker was bad.
If the new breaker trips, then the fault is in the water heater. Switch the new 2-pole breaker to off and disconnect the wires at the water heater.
Test the heating element of the water heater to see if it is shorted out. If it is, then you will have to replace the element or replace the entire heater if it is too old or shows signs of impending failure.
A 240V water heater should be supplied by a two pole (double) breaker, not two single breakers.
If a 240V water heater is wired to two independent single pole breakers, when there's an overload, it's a race. Naturally the two breakers are not exactly identical - one is going to trip first. Once one trips, the circuit is open and the other breaker is under no load, it won't trip.
Replacing the breaker is easy, but that may not be the problem; if there's an actual overload on the circuit, that must be identified and corrected. It could be the water heater itself, could be something else.
Don't keep resetting a breaker over and over - when a breaker brings a problem to your attention, you have to fix the problem for safety's sake.