ELECTRIC ARC
PROTECTION CLOTHING
The Hazard
Electric Arc originates from ionization of a conductive electrical interconnection between electrodes of different potentials, different phase relationships or one of these & the earth.
Depending upon the power & combustion period of an electric arc, different physical effects can arise as a result of high temperature. Even though it lasts just a fraction of a second, the amount of radiant energy released is huge. Temperatures upto 10000°C is possible in an electric arc which may cause high chemical aggression forming plasma cloud. Depending upon the intensity of the arc, the heat radiation can ignite nearby flammable materials. The molten metallic splashes which originate from the electric arc increases the chances of a major fire hazard.
Workers engaged in such hazardous working conditions require appropriate Protective Clothing.
Specially designed Arc protective Clothing from TaraSafe® will help insulate the wearer from heat, resist breaking open of garment and will not ignite or continue to burn when exposed to a high intensity, short duration explosion and electric arc fire. We offer Arc Rated clothing providing protection from 8 - 40 cal/cm2.
Suggested Norms
EN 61482
Protection against thermal hazards of Electric Arc
Determination of the arc rating(ATPV or EBT50) of flame resistant materials for clothing.
Under this standard the protection property of the fabric or the garment against the thermal effects of an electric arc event is defined as its Arc Thermal Protection Value (ATPV) expressed in cal/cm².
There is no pass / fail criteria under this standard as in case of the Box test. The fabric / garment should have a minimum ATPV rating of 4 cal / cm² according to this standard.
This standard specifies methods to test material and garments intended for use in Heat and Flame resistant clothing for workers exposed to electric arcs.
Protection Class 1 and protection Class 2 are safety requirements covering actual risk potentials due to electric fault arcs.
This standard specifies tests with which it is possible to evaluate materials and protective clothing based on the use of a directed and constrained electric arc under defined laboratory conditions - this is called the Box-test.
For the tests a low voltage procedure is used. The tests can optionally be carried out in two fixed test classes, selected by the amount of prospective short circuit current:
| Class | Arc [kA] | Time [ms] |
|---|---|---|
| 1 | 4 | 500 |
| 2 | 7 | 500 |
The garments must be used to cover the whole body, e.g. jacket and trousers, to attain the correct level of protection.
The clothing falling under the EN 61482-1-2 is further classified as a Category III product.
NFPA 70 E
Electrical Safety - American Standard
The National Fire Protection Association (NFPA) 70E is a comprehensive standard that establishes best electrical safety practices standards on how to protect workers from electric arc flash and arc blast exposure and resulting potential injury and death.
There are 4 Arc Hazard Risk Categories under NFPA 70E defined by the ATPV ratings:
Most people working with electricity only require clothing that meets category 1 (ATPV 4 cal/cm²) or 2 (ATPV 8 cal/cm²) protection characteristics.
NFPA 70E electrical safety standards are aimed more towards those workers who work in category 3 (ATPV 25 cal/cm²) or 4 (ATPV 40 cal/cm²) hazard situations. Their clothing must meet ATPV rating minimums throughout the life of the garment.
| Hazard Risk categories | ATPV (cal/cm²) |
| HRC 1 | ≥4 |
| HRC 2 | ≥8 |
| HRC 3 | ≥25 |
| HRC 4 | ≥40 |
