A system for detection of equipment connections to a thermostat. The thermostat may have one or more terminals with a one-to-one connection to one or more loads respectively of heating, ventilation and/or air conditioning equipment, and one or more terminals with a one-to-one connection to electrical power. One or more detectors may be connected one-to-one to each of the one or more terminals, respectively, for connection to the one or more loads, and the one or more connections to the electrical power. Each detector may be connected to a processor. Each detector may be configured to provide a signal to the processor relative to a corresponding terminal indicating a status of a connection of the terminal to a load or to the electrical power.