I would like to connect an analog electric clock to the upper and lower elements of my electric water heater so I can see how much time they are actively heating water. My objective is to evaluate the power use before and after adding a solar pre-heating system.
Each heating element has two 110v wires connected. No common wire.
I understand how U.S. 220v is 2 x 110v and can run on just two wires.
But 110v needs a common wire to complete the circuit.
As a test, I connected a clock to one of the 110v leads of each element and system ground (the thermostat cover screw).
Now the clocks run when each element is hot and I can tell how much time is spent heating water by each element.
I have since removed the clocks because I read that drawing 110v from one leg of a 220v and system ground is "against code, illegal and extremely dangerous".
But is it really dangerous? An analog desk clock draws very little power.
Georgia, USA
Each heating element has two 110v wires connected. No common wire.
I understand how U.S. 220v is 2 x 110v and can run on just two wires.
But 110v needs a common wire to complete the circuit.
As a test, I connected a clock to one of the 110v leads of each element and system ground (the thermostat cover screw).
Now the clocks run when each element is hot and I can tell how much time is spent heating water by each element.
I have since removed the clocks because I read that drawing 110v from one leg of a 220v and system ground is "against code, illegal and extremely dangerous".
But is it really dangerous? An analog desk clock draws very little power.
Georgia, USA
Clock water heater use
