Arc Flash Hazard Analysis

The arc flash is created in a fraction of a second and intensifies as a pressure wave develops that could cause hearing loss or break bones. As hot gases expand violently, the explosive destruction may expel equipment parts, which may cause physical injuries or death.

Anything that causes an electrical short circuit can release an arc flash:

• A dropped tool
• Accidental contact with a live electrical parts
• Corrosion build-up of conductive dust
• Improper work procedures
• Deteriorating insulation
• Improperly maintained electrical equipment

Potential arc hazards are affected by the available fault current; the system voltage; the environment surrounding the equipment, including cleanliness; and the type of protective relaying (The duration of the arc, and thus, the extent of potential resulting damage, could be affected by relay sensitivity and speed of operation).

While working directly with, or in the proximity of, energized electrical equipment, it is vital to observe safety guidelines related to arc flash hazards.

NEC (National Electrical Code) Article 110.16
Flash Protection. Switchboards, panelboards, industrial control panels, and motor control centers in other than dwelling occupancies that are likely to require examination, adjustment, servicing or maintenance while energized, shall be field-marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.

The NFPA 70E standard is intended to reduce the occurrence of serious injury or death due to arcing faults to workers who work on or near energized electrical equipment. The warning label should remind a qualified worker who intends to open the equipment for analysis or work that a serious hazard exists and that the workers should follow appropriate work practices and wear the personal protection equipment (PPE) appropriate for the specific hazard. For arc flash (PPE) clothing information visit the Magid Glove web site.

There are four other separate industry standards concerned with the prevention of arc flash hazard:

• OSHA 29 Code of Federal Regulations (CFR) Part 1910 Subpart S
• NFPA 70-2005 National Electrical Code
• NFPA 70E -2004 Standard for Electrical Safety Requirements for Employee Workplaces
• IEEE Standard 1584-2002 Guide for Performing Arc Flash Hazard Calculations

Compliance with OSHA involves adherence to a six-point plan:

1. A facility must provide, and be able to demonstrate, a safety program with defined responsibilities.
2. Calculations for the degree of arc flash hazard.
3. Correct personal protective equipment (PPE) for workers.
4. Training for workers on the hazards of arc flash.
5. Appropriate tools for safe working.
6. Warning labels on equipment

OSHA enforces compliance of these standards.

Analysis
DYMAX's professional engineering staff can assess the electrical equipment in your facility to determine the hazard class and recommend the personal protection equipment (PPE) mandated by NFPA 70E-2004 and OSHA to be used in the proximity of electrical equipment being energized or de-energized.

To ensure your compliance with OSHA standards, DYMAX will:

1. Assist with or develop a site-specific safety program with defined responsibilities.
2. Perform a walk-through of your facility to collect data and update existing one-line diagrams, if needed.
3. Perform a Coordination Study and Short Circuit Analysis for the calculations for the degree of arc flash hazard.
4. Establish the flash hazard boundaries for qualified and unqualified personnel.
5. Recommend the appropriate PPE.
6. Provide site-specific electrical awareness training for workers.
7. Recommend appropriate tools for safe work.
8. Generate warning labels with flash hazard boundaries and PPE information for all electrical equipment.