Background: I removed an in line wall heater thermostat from a 120v outlet, and want to ensure I reconnect the wires accurately.
Question: A google search hit insists the wire marked in red is running from the the panel, and if tested should be active if circuit is on, and should connect to the "L1", the other wire black and not labeled runs to the heater and connected to the "T1". Is this accruate? Is testing the connection with circuit on necessary? Out of curiosity, do the characters stand for anything?