ELECTRICAL MONITORING, FAILURE-SENSING, INDICATING, ALARM, SIGNALLING AND SUPERVISORY EQUIPMENT FOR USE IN COMBUSTION SAFE GUARD SYSTEMS-NAMELY, CONTROL PANELS FOR SUPERVISING BURNERS, FIRST-OUTAGE FAULT FINDERS, AND IN PANEL-MOUNT AND PLUG-IN MODULAR FORM POWER SUPPLY UNITS, FAULT DETECTING UNITS, LAMP-FLASHING UNITS, ALARM CONTROL UNITS FOR HORNS AND LIKE SIGNALLING DEVICES, TRANSFORMERS, RELAYS, AND SWITCHES