Keeping workers safe from arc flashes is critical to safety in substations, e-houses, oil and gas sites, and any other industries where high voltage is involved. The consequences of incomplete protection can be catastrophic. Arc flashes are not forgiving.
What Is an Arc Flash?
An arc flash is a type of electrical explosion created by a connection through the air, or ground, to another voltage phase. This explosion produces heat, light, and enough electrical energy to cause serious injury, damage, or start a fire. Controlled arc flashes are created through everyday industrial processes like plasma cutting and welding.
(Learn about Major Safety Concerns for Welders and What to Do About Them.)
An uncontrolled arc flash can reach temperatures in excess of 35,000°F. It can melt metal conductors and produce an explosion of exceptional force. People and surfaces in the blast zone can be exposed to vaporizing temperatures. This is why it's not only so important to provide head to toe protection but to ensure that it's the proper type of protection.
Arc Flash Safety
OSHA requires workers to be trained on how to distinguish live parts, minimum approach distances, safe work practices, safety procedures, and safety requirements related to their jobs. They must also be trained on the use of insulated tools, personal protective equipment, and insulating and shielding materials for working on or near energized equipment.
For this article, we will focus on head to toe arc protection. Before you purchase your arc flash PPE, however, you will need to determine the level of protection you need.
You'll need to determine the Arc Thermal Protective Value (ATPV) for your application. The ATPV is the maximum amount of energy the personal protective equipment could be exposed to in calories per centimeter squared (cal/cm2) without incurring second-degree burns.
There is also a threshold called the Energy Break-Open Threshold (EBT), which is the highest energy exposure levels where a protective garment does not experience break open. If a garment is exposed to energies higher than the EBT rating, there is potential for direct skin exposure or inner layers of the clothing to ignite.
If you're not sure what kind of protection you need, there are consulting services that can provide support with the process of creating, implementing, and maintaining your electrical safety program and ensuring compliance.
Once you've identified the level of protection you need, here's the equipment required to provide workers with protection from head to toe.
ANSI has three hard hat classes, according to their electrical protection performance:
- Class G (General): proof tested to 2,200 volts
- Class E (Electrical): proof tested to 20,000 volts
- Class C (Conductive): should not be used for situations where workers are exposed to electrical hazards
Choose the right class based on an assessment of the voltages your workers could be exposed too.
Arc Flash Hoods
Arc flash hoods are made of flame-resistant materials and should provide full head and neck protection. They must be worn in combination with a face shield to comply with NFPA 70E. Lift-front and pull-over styles are available.
Arc Flash Face Shields
Face shields must be designed for arc flash protection, absorb harmful UV radiation, and meet ANSI Z87.1 and ASTM specifications.
Rubber Insulating Gloves
Designed to protect workers from electrical sources, these gloves must be tested at least every six months. Some styles offer RFID technology to ensure traceability and to help insure your workers are equipped with the proper PPE to safely do their jobs.
Arc Flash Coveralls
Coveralls made from arc-flash-resistant materials should meet NFPA 70E and ASTM F1506 standards.
Hair and Beard Nets
Some industries will require hair and beard nets. Some are available with substantial ATPV value protection.
Arc Flash Protection Suits
Suits are available separately or in sets (including hood, coat, and overalls). They're often used where higher protection is required.
Look for the product's heat attenuation factor (how much heat does it resist in an arc flash incident). Ideally the garment would hold its flame-resistant capability over the life of the garment.
Dielectric footwear should be rated for the voltage that workers could be exposed to and meet ASTM F1117 standard specification for dielectric footwear. This specification is designed to provide additional isolation and insulation in case of accidental contact with energized conductors or circuits.
This type of footwear can come in a few different styles: boots that fit over existing footwear and protect the lower leg, rubber boots, or galoshes.
Arc-Rated Fall Protection
Arc-rated shock absorbing lanyards are designed for workers who need protection from arc flash and arc blast exposures while working at heights. They should meet all ANSI, OSHA and ASTM F887-05 Arc Flash Standards, which provides specifications for personal climbing equipment for workers exposed to arc flash hazards.
Workers should also be equipped with arc-rated harnesses and arc-rated fall limiters.
There are numerous other tools and equipment that can help protect your workers from arc flash, such as:
- Hot stick and attachments
- Grounding equipment
- Insulating covers, blankets, and line housings
- Guards and cover
- Insulated jumpers
- Voltage detectors
Complete an arc flash hazard risk assessment before choosing your protection. The objectives of the risk assessment should be to determine the potential for arc flashes, identify opportunities to reduce or eliminate the hazards, determine minimum safe working distances, the appropriate PPE, and the training workers will require.