How can I switch between a dishwasher and a 2 gallon undercounter water heater on same circuit?
You could run the power to the dishwasher and disposal through a current sensor and contacts on the sensor in series with a  coil on a relay. The power to the water heater could be taped ahead of the sensor, and connected through &quot;normally closed&quot; contacts on the relay. When current is detected in the sensor the contacts on the sensor would close, energizing the coil on the relay opening the N.C. contacts, breaking power to the water heater.