Five to 10 arc flash explosions occur in electric equipment every day in the United States, according to a presentation by Eddie F. Jones, Square D / Schneider Electric, and Progress Energy. This number does not include cases in which the victim is sent to an ordinary hospital. Instead, these incidents are so severe the victims require treatment from a special burn center.
Here’s what can cause electrical arcing:
• Inadvertent contact
• Loose connections
• Insulation failure
• Poorly maintained equipment
• Voltage transients
• Unsuccessful Short Circuit Interruption
• Animals (squirrels, snakes .. Etc)
Standards used to protect against arc flashes include: NFPA 70E, OSHA 1910, The National Electrical Code, and IEEE 1584.
What is an Arc flash Analysis? A study investigating a worker’s potential exposure to arc flash energy, conducted for the purpose of injury prevention and the determination of safe work practices and appropriate levels of PPE.
The analysis process consists of:
1 Collect system and installation data
2 Determine system modes of operation
3 Determine bolted fault current
4 Calculate arc fault current
5 Find protective device characteristic and arc duration
6 Select working distances
7 Calculate incident energy
8 Calculate flash protection boundary
9 Determine PPE (risk hazard) category
Numerous injuries and deaths are caused each year by arc-flash incidents. While arc-flash cannot be completely eliminated, there are many things that we can do to prevent it. The single most important thing we can do to prevent arc-flash incidents is to place the equipment in a “safe working condition.” If it is more dangerous to turn the equipment off workers must wear appropriate PPE.