I have a 2 pole circuit breaker in the panel with a 2/12 cable connected to it. Black wire is connected to one pole, white wire is connected to other pole and bare wire is connected to ground bar. This cable runs to a wall mounted box where a 4 wire 240V dpst thermostat will be installed.
Testing, at wall box, black wire is 120V and white wire is 120V. The thermostat has two load wires and two line wires and it seems that connecting the 120V black wire to one of the line wires and the 120V white wire to the other line wire is how 240V gets to the baseboard heater via the two load wires. Is that correct?