The distance of the boundaries will vary, and depend on: Restricted approach boundary – the distance from an exposed energized electrical conductor or circuit part a qualified person (only) may approach when there is an increased likelihood of electric shock due to electrical arc over combined with inadvertent movement.Limited approach boundary – the distance from an exposed energized electrical conductor or circuit part a person may approach when a shock hazard exits (i.e., if the person is wearing appropriate PPE and are supervised by a qualified person).

There are two types of boundaries that are used: A second-degree burn is usually treatable.

It is assumed that a second-degree burn occurs when the incident energy received by the skin equals 5 J/cm2 (1.2 cal/cm2). What are approach boundaries? Back to topīoundaries are used to limit how close workers and others should be to the equipment or circuits, especially when work is being done.Īn arc flash boundary is the term used to describe the distance at which a person without personal protective equipment (PPE) may get a second-degree burn if an arc flash occurs.

Follow established maintenance requirements, including a parts replacement schedule.

Routine inspections of circuit breakers and relays (develop a testing schedule based on the manufacturer’s instructions or the InterNational Electrical Testing Association (NETA) guidelines).

Regular measurements of critical components.

Regular inspection for wear and tear of insulation, corrosion, poor connections, overheated electrical conductors, excessive pitting of contacts, or excessive moisture, water, or ice on the equipment.

What would be included in preventive maintenance? Back to top

Wearing shock and arc flash personal protective equipment (PPE).

Implementing work permits, safe work procedures, and job planning.

Using non-contact instruments or procedures, where possible.

Using arc flash approach boundaries, including barricades.

Guarding energized electrical conductors and circuit parts.

Using lower energy equipment or current energy limiting devices.

Making sure conductors and circuit parts are in a safe working condition.

Always follow lockout/tagout procedures as part of a hazardous energy control program. Whenever possible, do not work on energized equipment. What are some protective measures that can be taken? Back to top Also important is the condition of the electrical equipment, and the effectiveness of any maintenance activities. When estimating the likelihood and severity of the event, consider factors such as the design of the electrical equipment, the presence of an overcurrent protective device, and operating time.

determine what protective measures are needed, including personal protective equipment (PPE).

determine the likelihood of an arc flash, and the injuries it may cause.

What elements should be considered when doing an arc flash risk assessment? Back to topĪn arc flash risk assessment should be done to: The possibility of an arc flash increases when there are exposed energized electrical conductors or circuit parts or when safe work procedures are not followed.

Incorrect installation of arc-resistant equipment.

Incorrect installation of conductors, such as when conductors of different phases are installed too close.

Dust and condensation on the insulating materials (The dust or moisture provide a path for the electrical current and can lead to flashovers that create an arc discharge).

Equipment failure due to poor maintenance or improper design.

A tool dropped on the ground, which creates a spark which starts an arc discharge.

Unintentional tool contact with live parts.

The pressure wave can also cause damage to hearing or the brain.Īn arc flash may be caused by many factors or events, such as: Droplets of melted material and fragments of damaged equipment are spread by the blast at far distances at speeds fast enough for the items to penetrate the body. The blast will cause falls and impact injuries. The heat can cause severe burns which can be fatal. What are the hazards related to arc flash? Back to top In addition, an arc flash will create an arc blast - the heated air expands suddenly and creates a powerful pressure wave (a blast). At these high temperatures, items within a metre (3 feet) such as clothing and skin will catch fire, melt, or vaporize. Arc flash refers to the flash of light and heat that is created when energy is released between a live conductor and another conductor or the ground.ĭuring an arc flash, the energy released heats the air to extreme temperatures such as almost 20 000 ☌ (35 000 ☏).

Welding arc flash boundary chart