The NEC requires over current protective devices (OCPD) to protect cables from overheating and catching fire which is achieved using long-time (LT) breaker settings. The NEC also provides guidance on ground fault (GF) and ground fault delay (GFD) settings. Additional settings on OCPDs include long-time delay (LTD), short-time (SD), short-time delay (STD), and instantaneous (I), which can be adjusted and coordinated to protect personnel and equipment from dangerous fault currents. If the only goal was…
Its official, the new edition of IEEE 1584 – IEEE Guide for Performing Arc-Flash Hazard Calculations was approved by the IEEE-SA Standards Board in September 2018, shifting the paradigm of how arc flash data collection, analysis, and calculations are performed. Read more…
Prior to the 2018 version, NFPA 70E simply cautioned that “greater emphasis may be necessary with respect to de-energizing” equipment with incident energy (IE) exceeding 40 cal/cm2, “when exposed to electrical hazards.” This nebulous direction was applied within the industry by simply labeling everything over 40 cals as “Dangerous – No PPE Exists.” In its new 2018 version, NFPA 70E eliminated this cautionary language. This may lead some to infer that working on energized equipment…