Arc blast and flash risk and resulting injuries must be taken into account when installations are designed, operated and maintained. Arc impedance can hold the arcing current below 50% of the prospective fault current, so protection may be slow to act and the arc lasts longer; injury comes mainly from radiant heat and the plasma fireball, and incident energy of about 1.2 cal/cm2 can cause second degree burns and ignite cotton clothing. Three-phase equipment protected at 63 A or more may exceed that level. Incident energy may be quantified with IEEE 1584 or an equivalent method, and a PCBU with high current equipment rated 800 A or more should commission an arc fault study within its hazard identification and control process; other installations may also need arc flash assessment. Arc faults can cause explosions, melt cubicles and throw debris, and protection devices may not operate to prevent them.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.