An air conditioning system condensate collection pan or water leak containment pan electrical control switch includes a housing or frame for supporting a switch unit which includes an elongated actuator arm. The housing includes a slot disposed adjacent a distal end of the actuator arm for receiving a water soluble tablet engageable with the actuator arm to bias the arm into a predetermined position of the switch. Abnormal accumulation of condensate or leaking water dissolves the tablet and allows the actuator arm to move to a position to effect actuation of the switch. The switch may be connected to a control unit, a thermostat and/or to an alarm generator including a self-contained unit having battery powered audio and/or visual alarm devices, an on-off switch and a circuit test switch.