The customer was having an issue with the water heater located in the garage tripping the breaker in the main panel. The panel is a CH 150 amp main lug and the water heater is a 2p25 breaker located at bottom left of the panel board and is labeled properly. The breaker was in the closed position when I had arrived and I used an amp probe and did not see that any current being drawn. I noticed a disconnect by the water heater and it had a shut off switch and when I went to shut it off it started to sizzle indicating arcing was being produced. I shut the circuit breaker off and removed the cover on the disconnect and found burnt wires on the load side of the disconnect and the terminals were also burnt as well. This was caused by loose connections resulting in power loss, tripping breaker and damage to the disconnect. While the power was down I checked the termination point at the water heater and found that the wires were not twisted together and the bonding screw was not tighten do