Abstract: A remote unit monitoring system is provided which monitors any number of hazard conditions in an electrical substation and transmits this information via telephone lines and radio link to a central station. The system automatically dials the central station, after checking the integrity of each communications channel. Data is transferred only after a kissoff signal is received from the central station indicating that the communication channel is secure. The substation continues transmitting the data until the data accuracy is verified by the central station. Battery backup of all critical circuits is provided as well as visual indications of any failure in the system. The central station is provided with the ability to query the substation at any time.