Thermostat switching circuitry with overcurrent shutdown

A thermostat comprising:

• a plurality of wire connectors configured to receive a plurality of wires from an environmental control system, the plurality of wire connectors comprising a call relay wire connector and a power return wire connector;
• one or more solid-state switching elements coupled to the call relay wire connector and the power return wire connector, the one or more solid-state switching elements having a first operating state in which the one or more solid-state switching elements create a connection between the call relay wire connector and the power return wire connector, the one or more solid-state switching elements also having a second operating state in which the connection between the call relay wire connector and the power return wire connector is interrupted;
• a zero-crossing detection circuit that detects when an electrical signal of the one or more solid-state switching elements is zero;
• and
• power monitoring and control circuitry coupled to the one or more solid-state switching elements and configured to:
• cause the one or more solid-state switching elements to operate in the first operating state to actuate at least one environmental control function;
• measure the electrical signal of the one or more solid-state switching elements when the one or more solid-state switching elements are operating in the first operating state;
• detect an anomaly associated with the electrical signal;
• in response to detecting the anomaly, store an indication that the anomaly occurred while continuing to cause the one or more solid-state switching elements to operate in the first operating state;
• receive an indication from the zero-crossing detection circuit that the electrical signal of the one or more solid-state switching elements is zero;
• and
• in response to receiving the indication from the zero-crossing detection circuit, cause the one or more solid-state switching elements to operate in the second operating state.