The causes and effects of arc flash on industrial and commercial sites

by | May 27, 2016 | Blog, Engineering Design & HSE

Put simply, arc flashes are electrical discharges, or short circuits, that move through the air. Moreover, arc flashes are a dangerous hazard, to you, your staff and your site’s assets. And they aren’t just limited to high voltage systems: more than half of all electrical accidents associated with low-voltage switchgear assemblies for example, involve arc faults. To put it in to context, you and your staff are at higher risk of suffering an injury or worse from an arc fault at your site, than you are from an electric shock.

The causes of arc faults vary, but in most cases they are the result of human error or the failure of equipment. Indeed, the majority of arc accidents occur while equipment is being operated. Removing the risk completely is therefore not really an option as you can’t monitor or control the actions of your employees on a constant basis. Knowledge however, is a good first line of defence. While it won’t stop an arc fault from occurring, equipping your staff in some basic facts about arc faults may go some way in limiting the subsequent damage and preventing injury.

Some of the most common causes of arc flash include:

  1. Poor electrical contact
  2. Insulation failure
  3. Inadvertent contact with energised equipment
  4. Ageing electrical systems
  5. Inadequate maintenance of electrical systems

Arc flashes can be deadly, or in the very least can cause significant injury.

Some of the potential effects of arc flash include:

  1. Burns – arc flashes create phenomenal heat and intense thermal radiation. Temperatures in a single arc flash can reach up to 35,000 degree centigrade. Compare that figure to 9,000 degrees centigrade, which is the approximate temperature of the surface of the sun.
  1. Injury from blast pressure – an arc flash can create a staggering and deadly force that’s upwards of 2000 lbs/sq. ft.
  1. Lung damage – arc flashes can create the potential for the release of vaporised metal droplets and poisonous nitrogen dioxide gases which if inhaled, will have dire consequences on respiratory systems.
  1. Hearing loss – the explosive expansion of the air surrounding an arc flash can generate dangerously high sound levels, which can cause significant hearing damage to those in the vicinity of the arc flash.
  1. Damage to sight – the intense light from an arc flash can cause temporary or permanent blindness.

In addition to effects to human life, arc flashes damage equipment and assets, causing the potential for significant downtime and losses in production.

It’s important to remember that while equipping your employees with the correct Personal Protective Equipment (PPE) is critical, it should definitely not be the sole line of defence. The mitigation methods for arc flash can vary from site to site, just as much as its causes and effects. To ensure your site has the correct methods for its environment, you need an arc flash expert to conduct a thorough risk assessment based on the appropriate calculations.

Arc Flash Hazard Capability Statement

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