Arc Flash Hazards
Date Posted: 02/08/2024
Based on findings from the Bureau of Labor Statistics (BLS), it’s estimated that between five and ten arc fault incidents occur daily in the United States. The BLS also reported that in one recent year, 1 thousand electrical workers suffered shocks and burns, some fatal. Arc flashes are violent and can cause severe injury or death to any worker exposed to the instantaneous phenomenon. Most of the time, the exposure will result in severe injury or even death. Electrical equipment is designed to withstand up to a certain amount of current. The arc flash occurs when an electrical device suffers a very high current within a fraction of a second. Some factors that can cause an arc flash include failure to de-energize components, dust, dropped tools, corrosion, or reduced insulation. Arc flash temperatures can become exceedingly hot and produce hazardous noise about as loud as a gunshot.
What is Arc Flash?
According to the National Institute of Occupational Safety and Health (NIOSH), “An arc flash is the sudden release of electrical energy through the air when a high-voltage gap exists, and there is a breakdown between conductors. An arc flash gives off thermal radiation (heat) and bright, intense light that can cause burns. Temperatures have been recorded as high as 35,000 °F.”
What is an Arc Blast?
An arc blast is a pressure wave created after an arc fault. Arc blasts can be strong enough to throw a worker to the ground and cause significant equipment damage. Arc blasts can cause damage to a worker's hearing or brain functions. The blast can also cause loose equipment, tools, machinery, and debris to go flying, which can cause further damage or injury. For example, consider the following facts on arc blast:
Air and materials exposed to ARC flash expand to be 67,000 times their normal size.
The violent pressure wave discharged can reach up to 2,000 lbs./sq. foot, causing severe risks, including:
Eardrum damage
Lung damage
Sound that exceeds 140 dB.
Molten metal and shrapnel that exceeds 700 mph.
What Causes an Arc Flash?
Arc flash can be caused by many things, including:
Accidental touching
Water or liquid near electrical equipment
Material failure
Static electricity
Live work on damaged equipment
Lack of awareness of training
Touching a test probe to the wrong surface
Worn or loose connections
Gaps in insulation (exposed live parts)
Improperly installed or maintained parts
Dust
Corrosion
Dropping tools
How Can You Protect Yourself from the Hazards of Arc Flash?
Best Choice for Arc Flash Protection: As a worker, you should only work on de-energized equipment or machinery. The first step in avoiding an arc flash event is to turn off electrical energy at the source utilizing appropriate lockout and tag-out procedures before attempting any sort of repair. If live parts are not placed in an electrically safe work condition, the work performed is considered energized electrical work. Energized work should only be authorized in minimal conditions. These are:
De-energizing would create a more significant hazard, or it is necessary for the interests of health and safety that the electrical work is carried out while the equipment is energized (e.g., it may be required for life-saving equipment to remain energized and operating while electrical work is carried out on the equipment).
It is necessary that the electrical equipment to be worked on is energized for the work to be carried out correctly.
It is necessary for testing or troubleshooting.
There is no reasonable alternative means of carrying out the work.
Note: Use appropriate lockout, tagout, and hazardous energy control procedures to isolate energized equipment when a circuit breaker or other disconnect is turned off. The best arc flash protection is to de-energize equipment before working on it!
Second Best Choice for Arc Flash Protection: Use appropriately rated personal protective equipment (PPE). Arc flash personal protective equipment (PPE) is a combination of clothing and safety equipment worn for protection from arc flash and shock hazards by a person performing electrical work. Primarily, arc flash PPE is divided into the following subgroups:
Head, face, neck, and chin protection
Eye protection
Hearing protection
Body protection
Hand and arm protection
Foot and leg protection
General Electrical Safe Work Practices
All employees working on or near electrical equipment shall follow general safe work practices, including:
Maintain housekeeping procedures in the work area, e.g., prevent slip trips and falls; eliminate fire hazards; control dust; prevent falling hazards; clear clutter.
Plan and analyze each step of a work task to ensure safety.
Maintain appropriate work boundaries for qualified electrical workers (QEW) and unqualified workers.
Use properly rated and tested test equipment (e.g., multimeter).
Understand and be prepared to implement applicable emergency response procedures.
Always wear appropriately rated PPE when working on or near electrical equipment.
Refer to equipment drawings and equipment instructions when available and appropriate when planning work tasks.
Perform required testing in electrical enclosures (test boxes), which reduce or eliminate the possibility of contact with live electrical circuits.
Maintain electrical equipment in accordance with the manufacturer’s instructions and limitations.
