Electrical design - refined for safety

A typical electrical system and equipment layout is designed to conform with certain standards such as National Fire Protection Association's NFPA 70 or International Electrotechnical Commission's IEC 60364-1. The occupational safety and health administration also sets forth design safety standards for electrical systems under 29 CFR Subpart S 1910.302-308. These documents contain fundamental principles of safety for protection against electric shock, thermal effects, overcurrent, fault currents, and overvoltage. After an initial electrical system design is complete, and the electrical system studies, including short circuit, protective device, and arc flash calculations are performed, current knowledge of arc flash hazard may dictate that the electrical design be refined for safety. An electrical design-refined for safety would consider methods to eliminate or reduce electrical failures, to lower any fault current magnitude, and to increase speed of protective device clearing. The purpose of this presentation is to identify and document the benefits to be gained from the use of such things as high resistance grounding, "see-through" rigid barriers, "fingersafe" fuses, insulated buses and terminal covers, arc resistant switchgear and controlgear, "enhanced safety" motor control centers, and/or appropriate personal protective clothing/personal protective equipment. "Electrical design-refined for safety" is an innovative and cost effective way to complement and supplement regulations and codes requirements. It can enhance employees' safety without excessive reliance on administrative controls. It can eliminate or reduce the burdens associated with obtaining special permits required for common tasks, such as meter reading, lock out/tag out, etc. "Electrical design-refined for safety" is the careful application of engineered safety features to enhance safety for personnel who must, from time to time, work in an environment affected by proximity to exposed energized electrical conductors and circuit parts