4 now outlines guidelines for adding necessary descriptions to circuits, circuit modifications, and power sources in a listed manner, with clarity to avoid any existing confusion. Proper electrical panel labeling is a critical safety requirement that helps prevent electrical accidents, ensures code compliance, and enables quick circuit identification during emergencies. You need to label every circuit breaker clearly and accurately to meet National Electrical Code (NEC). One essential aspect of electrical safety is the proper labeling of industrial electrical and control panels. These symbols communicate the device's resting state, type of mechanical action (momentary. he system is modified (Rule 2-100). The Ontario Electrical Safety Code (OESC) also requires high voltage systems with the possibility of feedback to have updated single-line diagrams — both at the time of installation and af er any modifications ( labelling directly impacts safety. Increased Risk of Electrical.