- What exactly is arc flash?
- An arc flash is caused by an arcing fault – a type of electrical explosion due to a rapid release of energy
- Pressures are generated 100’s – 1,000’s lb/ft²
- Sounds due to pressure waves can exceed 160 dB
- Debris & molten metal can reach speeds that exceed 700 mph
- the flash can reach temperatures in excess of 30,000 degrees Fahrenheit
- Extreme temperatures can vaporize copper wires
- What are the applicable standards?
- NFPA 70E-2015: a standard of the National Fire Proteciton Association, an dis the consensus ‘Standard for Electrical Safety in the Workplace.’ It began in 1976 to assist OSHA and was published in 1979. NFPA70E-2015 provides a practical, safe workplace relative to the hazards associated with electrical energy.
- OSHA 29 CFR 1910.269: an arc flash law for power generation, transmission, and distribution
- There are Arc flash PPE (Personal Protection Equipment) requirements for both NFPA70E & OSHA 1910.269. This quick clip below visualizes the difference between flame resistant fabric and non-flame resistant fabric.
- What is the difference between FR (flame resistant) and AR (arc-rated) fabric?
- The most important thing to remember is that ALL arc-rated fabrics are flame resistant, however NOT all flame resistant fabrics are arc-rated
- To be considered flame resistant, the fabric must:
- Self-extinguish within 2 seconds or less
- Not melt or drip
- have a char length of 6″ or less
- Arc-rated material must be Flame Resistant per ASTM F1506. This includes a Vertical Flame Test to prove flame resistance, in addition to being tested per ASTM 51959 to determine the fabric’s arc rating.
- How is Personal Protection Equipment rated for Arc Flash?
- There are two values that represent an arc rating
- ATPV (Arc Thermal Performance Value: represents incident energy that results in 50% probability of a second degree burn.
- Ebt (Energy Break Open Threshold): represents incident energy that results in 50% probability of a break open. The material breaks open during arc testing before a burn could be registered.
- Both ATPV & Ebt ratings may be reported, but the lower of the two ratings defines the official arc rating of the garment and must be on the garment label.
- There are two values that represent an arc rating
- What do you need to wear to safe & compliant?
- NFPA & OSHA share general requirements for coverage:
- Clothing shall cover potentially exposed areas as completely as possible
- Shirts, coveralls & jackets shall be closed at the neck
- Sleeves shall be fastened at the wrists
- Shirts shall be tucked into pants
- Different levels of protection are defined into four different PPE categories (a hazard risk assessment needs to be performed in order to fully understand your specific hazard and the protection it requires).
- NFPA & OSHA share general requirements for coverage:
CBT partner National Safety Apparel (NSA) has a wide range of personal protection equipment to keep you safe from arc flash. For information on PPE selection and purchasing, contact your CBT specialist today! For further guidance on arc flash, sign up for one of our arc flash training sessions.
