Mike Dolt Enterprises
Mike Dolt Enterprises
User: anbm, Location: Suwanee, GA
Asked on: Wednesday, April 27, 2011 at 4:55 pm EDT
Answered on: Tuesday, May 14, 2024 at 4:42 am EDT
Question: Most of the time, around 10% of bus result from arc fault calculation (for incident energy) are more than 40 cal/cm2 which is more than category 4 from NFPA-70E table. Then, what type of cloth or protection should the service persons wear to service the elec. gears re replace breakers? NFPA-70E does not address this. It is strange!
Arc Flash Protection Clothing and Procedures for High Incident Energy Levels
While NFPA-70E does not provide specific guidance for arc flash protection clothing for incident energies exceeding 40 cal/cm2, other industry standards and guidelines can be consulted.
NFPA 1977: Standard on Protective Clothing and Equipment for Workers Exposed to Electric Arc Flash
NFPA 1977 provides requirements for protective clothing and equipment for workers exposed to electric arc flash hazards. For incident energies above 40 cal/cm2, the standard recommends: Level 4 Garments
Nomex or equivalent fabric providing protection of 40-80 cal/cm2.
Level 5 Garments
Indura or equivalent fabric providing protection of 80-120 cal/cm2.
IEEE 1584: Guide for Performing Arc-Flash Hazard Calculations
IEEE 1584 states that for incident energies "off the scale" of NFPA 70E (i.e., >40 cal/cm2), "the use of special engineering controls or work practices is necessary." These may include: Remote Operation
Using tools or robots to perform tasks at a distance.
Specialized Protective Clothing
Garments designed for incident energies above 120 cal/cm2.
Adequate Training
Ensuring that qualified personnel understand the hazards and use proper work practices.
Additional Considerations
The type of protective clothing selected should be based on a risk assessment considering the specific work task and equipment involved. Protective clothing should be properly fitted and maintained according to manufacturer's instructions. Service persons should use additional measures such as insulated tools, arc shields, and grounded equipment to minimize the risk of exposure.
Protocols for Replacing Breakers with High Incident Energy
Circuit Deenergization
The circuit should be completely deenergized and locked out/tagged out before any work is performed.
Arc Flash Risk Assessment
An arc flash risk assessment should be conducted before any work is performed to determine the potential incident energy levels.
Proper Protective Gear
Service personnel should wear appropriate protective clothing and equipment based on the arc flash risk assessment.
Preformed Maintenance: All maintenance tasks should be performed according to established procedures and industry best practices. Flag for review