Thank you for you time. I have an electric tankless water heater. I only have a 200 amp panel in my home and this water heater is wired for 120 with 3x40 amp breakers. I have been told by several folks this should never have been put in my house and could cause potential damage to our home. Becuase of the draw of the water heater we have flickering lights when its on and the breaker has tripped if we run the dryer or oven at the same time as the hot water. My plan is to remove this and put in a 55 gallon tank electric water heater. I know that this will require only one 30 amp breaker. I have some questions about how to accomplish this myself safely.
I believe that I can replace the breaker (40 amp) that will support the new water heater with a 30 amp breaker and not have to change any wiring as you can downsize wire but not upsize. Is this correct?
For the other two 40 amp lines that will not be used, what is the best way to decommission those? I know I can get blanks for the panel, but wanted suggestions for best practice. I can cap the wires themselves or possibly pull them, the water heater is on the same wall as the panel.
Thank you again for any and all suggestions. I consider myself a fairly competent around the house handy man but a very, very novice electrician. I can upload some pictures later if that might help and provide any more info.