Abstract: A switching device is enclosed in a casing fixed to a wall below a ceiling-mounted conventional smoke detector, so as to be accessible. The switching device includes a holding relay, a dry-cell battery and a time-delay circuit. The dry-cell battery replaces a similar battery normally in the smoke detector itself. In normal position, the holding relay connects the battery of the switching device to the circuit of the smoke detector. Whenever the smoke detector sounds a false alarm, a house occupant actuates the holding relay to disconnect the smoke detector circuit and stop the alarm. The battery in the switching device thereafter is connected to the time-delay circuit which returns the holding relay to its normal position after a period of, say, twenty minutes.