Electrical arc flash is produced when a spark jumps across the space between two electrodes with different potentials, producing ionized gas allowing electric current to flow through the air. The ionized gas generated in the electric arc is called plasma, and can reach extreme temperatures of tens of thousands of degrees Celsius. In industry, arcing can be caused by technical failure or human error.

ARC FLASH HAZARDS

The consequences that a worker may suffer as a result of exposure to an electric arc are diverse, such as high-pressure waves, splashes of molten metal, noise, exposure to ultraviolet radiation, etc. But the most relevant is the risk produced by exposure to high temperatures for a certain period of time.

TESTING STANDARDS

There are several test standards and guides to determine the level of protection offered by materials and personal protective equipment (PPE) against the thermal risk produced by an open, multidirectional electric arc.

The following are the guidelines for calculating the level of protection required for workers at risk of exposure to electric arc:

The standards that determine the level of protection offered by materials and personal protective equipment (PPE) are divided into two blocks: testing standards and requirements standards.

• Test standards, where the method to evaluate the Arc Rating of the products is described are:

The requirements standards specify the whole set of standards that a product must meet in order to be certified.

ARC RATING

The level of protection offered by a material against exposure to an open electric arc is called its Arc Rating, expressed in cal/cm². To understand what the Arc Rating is, it is necessary to know what the incident energy is. Incident energy is the amount of heat to which a sample is exposed for analysis.

The Arc Rating can come from different characteristics evaluated in the laboratory test:

• Arc Thermal Performance Value (ATPV): Incident energy for a material to exhibit a 50% probability of second degree burn. [cal/cm²] [cal/cm²] [cal/cm²] [cal/cm²] [cal/cm²
• Breakopen Threshold Energy (EBT): Incident energy for a material to show a 50% probability of breakage. [cal/cm²] [cal/cm²] [cal/cm²] [cal/cm²] [cal/cm²
• Incident Energy Limit (ELIM): Incident energy of a material below which no second degree burn or breakage has been observed. [cal/cm²] [cal/cm²] [cal/cm²] [cal/cm²] [cal/cm²

The main characteristics of the open arc laboratory test are as follows:

• Current 8kA.
• Stainless steel electrodes.
• Distance between electrodes: 300 mm.
• Distance between the sample and the center of the arc: 300 mm.
• Multidirectional electric arc.

At AITEX, we have two chambers with the capacity to carry out all tests related to the open electric arc test.