ATPV 21 CAL/cm2 fall into category HRC 3 arc flash protection.
Electrical applications above 1000 volts with low to medium risk energy levels
Arc flashes occur when electricity jumps across the phases and cause a short circuit and subsequent flash. Arc flash occurrences are a factor of the distance between the phases and distance from the source (transformer) , the circuit breakers trip time, the available short circuit current, dirt buildup in the equipment which may affect the conductive path, moisture (humidity), circuit supply voltage, amount of motor contribution during a fault, indoor versus outdoor applications and the distance of the operator from the switchgear.
Applications with medium voltages and lower fault levels have lower energy levels. Electricians working on distribution boards in various factories , mining and industries with medium voltage applications are not free from arc flash occurrences. Although lower voltages are less likely to jump across phases , when these do occur the arc flash can be just as severe and harmful a higher voltages when the conditions allow.
To provide adequate protection, the electrician should be protected from head to toe. The APTV 21 CAL headkit has a tinted visor that protects from thermal effects, conductor shrapnel and blinding light generated from the arc. APTV 21 CAL Jackets and trousers are available in only two piece. APTV 21 CAL Gloves are designed to provide maximum dexterity so that the electricians work is not inhibited. 20000v boots provide the insulation for live work conditions and a bag holds all the equipment together.