Electrical apparatus, namely, air disinfection units for use in HVAC ducts comprising lighting ballasts and electrical power supplies for powering an electrically operated source of ultraviolet light, and microprocessor controlled electrical circuit boards for monitoring the performance of an electrically operated source of ultraviolet light; air disinfection lighting ballasts; electrical power supplies for powering an electrically operated source of ultraviolet light in HVAC ducts; microproc...