Abstract: A window air conditioner includes an electrically grounded outer case and an air conditioning unit (compressor, condenser, evaporator, etc.) slidable into and from the outer case. Mounted in the outer case is a pair of horizontal metallic rails upon which the unit slides. The rails include sharp projections extending upwardly into contact with a metallic base of the unit to cut through a film, such as paint, disposed on the base, in order to make electrical contact with the base. The unit is thus electrically grounded through the base, rails, and outer case.