Abstract: An automatic temperature control system for a building that includes a night setback feature and a morning pickup feature that operates as a function of outside air temperature and wind velocity. A seven day time scheduler and a short cycle auxiliary timer control the system operation. System automatically resumes proper scheduled operation following power failure that does not exceed mechanical carry-over time of seven day time scheduler.

Abstract: An improper or undesired second ground connection on the load side of the neutral conductor of an electrical supply system is detected by coupling an oscillator to the neutral conductor and to least one other conductor of the supply system in a balanced mode. In the absence of said improper or undesired second ground, oscillator signals cancel on the two conductors. When said second ground is present, oscillator current flows therethrough and the impedance change in the grounded neutral conductor is reflected back to the oscillator tank circuit to change the output signal of the oscillator. Change in output signal is detected and actuates circuit breaker to disconnect the supply system.