Electric Shock

TECHTRIC ENGINEERING - ARC FLASH

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Arc Flash CSA Z462

What is the Issue?

Arc Flash is an explosion caused by the release of energy in an electric arc.

Causes:

  • Dust, water, impurities,​ contamination, corrosion, animals

  • Accidental contact, dropped or improper tools

  • Over-voltages across narrow gaps

  • Insulation failure

  • Loose connections

  • Equipment failure

  • Working near energized equipment without appropriate PPE

Arc Flash Fire

The Dangers

  • Thermal temperature can reach over 5000 degrees​

  • Blinding light, deafening noise

  • Copper vaporizes and expands by a factor of 67,000

  • Produces a lethal spray of molten steel and shrapnel

  • Pressure wave of up to 2000lbs per sqft

Personal Injuries

  • Electric shock, severe burns, blindness, deafness, shrapnel wounds, lung blast injuries, concussion, collapsed lungs, death​​

Damage to Business and Property

  • Damaged/destroyed equipment,​​ production downtime

  • If the cause is found to be due poor maintenance or neglect: fines, imprisonment, business closure

Electrical Fire
Arc Flash Injury_edited.jpg
Hover to Reveal Injury
  • 30,000 electrical shock accidents occur each year.*

  • More than 2,000 people per year are admitted to burn centres with severe arc flash burns.**

  • Sixty-four occupational related electrical deaths occurred in Ontario between 1999 and 2008.**

  • In the same ten year period, 246 workers sustained critical injuries of an electrical nature.**

* Source – Electrical Safety Authority.

** Source – 2008 Ontario Electrical Safety Report.

Arc Flash PPE
Techtric Arc Flash Label

Your Responsibility and the Solution

To address this issue, The Canadian Standards Association has introduced CSA Z462.

Canadian legislation has now made it mandatory for all facilities with three-phase electrical power to properly identify and protect workers against risks associated with shock hazard and arc flash through labelling, training, coordination, etc.

What We Do

Arc Flash and Shock Hazard calculations are performed according to the latest IEEE, NFPA, and CSA standards to identify the maximum expected incident energy if an Arc Fault were to occur. To perform these calculations, it is necessary to understand the manner and method in which a system is protected.

The potential short circuit levels throughout the system need to be known and a complete set of protective device settings are required. Given this information, our engineers perform a series of calculations, looking at different operating conditions, loading levels, and generation levels. Worst case results are compiled, and from these results incident energy levels are categorized and documented for the entire three-phase electrical system. Approach boundaries and PPE are determined and labeling is installed, notifying all site staff and contractors regarding the potential hazards they might face when working at or near the electrical system.

Related Standards

  • CSA Z462-21

  • Canadian Electrical Code: Rule 2-306

  • Occupational Health & Safety Act

  • US National Fire Protection Association: Standard NFPA 70E

  • IEEE Standard 1584

  • Bill C45

Arc Flash Labelling

After conducting an Arc Flash Study, labels are made which identify the potential dangers of working on the live equipment. Below is a sample arc flash label and an explanation of the different boundaries and information displayed:

Techtric Arc Flash Label
  • Arc Flash Boundary: The maximum distance from an arc flash where someone would receive a second degree burn.

  • Arc Flash Incident Energy: The measure of thermal energy of an arc fault at the given working distance. Used to determine appropriate PPE.

  • Working Distance: The assumed distance between the equipment and the worker, used for calculating the arc flash incident energy. Usually 18 inches.

  • Shock Hazard: Hazard associated with the equipment voltage level.

  • Limited Approach Boundary: The minimum distance from the live conductors that should be maintained by people/workers not immediately working on the equipment. Used as a guide for setting up barriers when the live equipment is being worked on.

  • Restricted Approach Boundary: The distance from energized conductors in which a worker must wear insulated gloves.

  • Glove Class: Appropriate glove voltage rating class for this equipment. Based on equipment voltage.

Protective Device Coordination

As part of the Arc Flash study, we conduct a coordination study to assess the existing system coordination and to propose and evaluate improvements. Below is an example of a Time Current Curve (TCC) graph from a project with the details removed:

Techtric Time Current Curve

TCCs show which protective devices like fuses or circuit breakers will activate at certain times for a given fault current . This helps determine if the system has selective coordination and if arc flash incident energies can be reduced. Based on these as-found TCCs, improvements can be recommended and new TCCs can be made to show the results of the recommendations and changes.

Selective Coordination: The design of a system where the first device upstream of a fault or an abnormally high current detects the over‐current state and acts upon it. This detection scheme allows for the smallest portion of the distribution system possible to be isolated. Selective coordination is not always possible when trying to mitigate arc flash hazards in a system and vice versa.

Disclaimer: Arc flash photographs and videos are for training/educational purposes only and are not representative of Techtric Engineering’s Work

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