I am troubleshooting an electrical problem and am having trouble understanding the readings I am seeing on my digital multimeter. I am a DIYer with just the basics of electrical engineering knowledge, but would appreciate comments on what I am seeing and the physics behind it. Would this be expected based on Ohm's law?
Below is a schematic of my circuit which supports three electric baseboard radiators controlled by a single wall mounted thermostat. The heat had stopped working and when I removed the thermostat I found 2 tiny baby mice in the electrical box! After removing the mice I wanted to test to see if there might be any anomalies indicating chewed wire damage inside the wall and got the voltage readings shown on the diagram.
For those outside of the US and Canada, note that we get 220V by going across the two 110V wires from the line source, whereas our 110V is done by going from one of the two 110V sources to the neutral. So I understand the 120V reading on the first measurement.
I am not clear however as to why I got the other two readings. Note that all of these readings were taken with the thermostat switch open.
My question: Are the 20V and 70V readings I am seeing to be expected voltage drops due to the resistance of the radiators? Or could it be an indication of some line damage hidden in the walls?