Abstract: A wireless form of humidity control for residential and other uses and comprising; a carrier current type of transmitter and receiver used in combination and within a conventional electrical wiring system for a building, said transmitter including a step-down transformer and a humidity sensing device disposed in compact and close proximity and with the latter provided in the power supply line for said transformer for intermittent actuation of said transformer and consequent minimal heat generation therefrom, said transmitter and receiver having an operating frequency of at least half again that of the carrier wiring and said receiver having capacitance in the signal receptive connections thereto sufficient to provide an impedance low enough to pass a given high frequency signal and high enough to block the line potential frequency and variations incident thereto.