Trouble shooting an electric hot water heater that has defective heating elements

We work on a hot water heater that has stopped producing hot water. I check the voltage at the fuse box , the thermostat in the water heater, and the heating elements. I push the RESET button to see if the issue clears. The tank is drained and we find major deposits of minerals at the bottom and on the elements. After vacuuming out the deposits we replace the heating elements, refill the tank while watching for leaks, then take voltage readings after the tank is producing hot water again .
How to use a clamp multimeter to measure current, voltage and resistance:
• How to use a clamp mul...