A Short Circuit Study: What Is It & Why Do You Need One?

By Thomas Thrasher

A short circuit study is essential to understanding whether an electrical system is safe and reliable. Our team knows how to design systems that provide the standard level of safety for electrical equipment and has specialized expertise in refining system designs to ensure safety for the equipment’s users and operators. Short circuit studies can provide critical information about an electrical system that will ensure users are entirely aware of any dangers present in the system and that the system operates as it’s supposed to.

WHAT IS A SHORT CIRCUIT STUDY?

A short circuit study evaluates three major factors of an electrical system:

Short circuit/fault current levels at each panelboard,
Selective coordination between breakers/fuses within a distribution system to ensure the most reliability possible, and
Arc flash levels at each piece of equipment in the event of a fault (i.e., how much energy could be expelled).

Proper evaluation and remediation of any issues identified in a short circuit study can result in complete transparency of the risks on site and the highest possible reliability of a system in the event of a short circuit.

These studies require a thorough evaluation of existing building systems, including the development of complete single-line diagrams and floor plan layouts of the distribution equipment within a building. A single-line model is completed in short circuit evaluation software and then used to simulate a fault event at each board to confirm the worst-case issues that could be present at each location.

IS A SHORT CIRCUIT STUDY REALLY NEEDED?

It’s a common misconception to think that a short circuit study is unnecessary if a building’s system has operated without issues for years. However, one of the major issues our team has witnessed over the past few years is a massive increase in available fault current from the public utility. We’ve seen sites where fault current levels have jumped two to three times from what the system was originally designed to, which ultimately pushes much of the equipment in a building out of compliance and could result in a very dangerous situation if a fault were to occur.

If there are any questions or issues you’d like to discuss, please contact me by emailing tthrasher@wbengineering.com.