Short Circuit Study Services

A short circuit study calculates the available fault current at every point in your electrical system, then confirms that the equipment installed there is rated to safely interrupt it. It is the foundation of a defensible power system, and it is the first calculation behind any arc flash study.

If a breaker cannot interrupt the fault current available at its location, or a piece of equipment is not rated for the fault current on its bus, it may fail the day it is asked to do its job. A short circuit study finds those problems before they find you.

What a Short Circuit Study Determines

• The available fault current at each bus, panel, and piece of equipment
• Whether every protective device (breaker or fuse) has an adequate interrupting rating (AIC) for the fault current at its location
• Whether assemblies such as switchboards, panelboards, MCCs, HVAC units, and control panels have an adequate short circuit current rating (SCCR) or withstand rating for the fault current available to them
• Any equipment applied above its rating, so it can be corrected

What We Actually Find

A short circuit study is not a formality. Here is what it catches in the field.

Underrated equipment. HVAC units, control panels, and even standard switchboards carry a short circuit current rating (SCCR) or withstand rating. On paper they look fine. The study reveals when the available fault current at that location exceeds what the assembly is actually rated to withstand.

Breakers with the wrong interrupting rating. We find protective devices whose AIC rating is below the fault current available at their location, and not only in older facilities. We have found this on new construction, where everyone assumed the equipment was correct.

Series-rated combinations that were never verified. A downstream breaker can only rely on a higher series rating when the exact upstream and downstream combination is properly listed and applied. Series ratings are not blanket numbers, and substitutions happen in the field. When the installed combination is not the listed one, the rating no longer applies, and the protection people are counting on is not actually there.

These are the same problems I write about in 10 problems I commonly find when reviewing existing arc flash studies. A short circuit study is how they get caught.

When You Need One

• As part of an arc flash study, since the available fault current calculation is a required input to the incident energy analysis
• New equipment, a service change, or a facility expansion
• A utility upgrade that may have changed your available fault current
• Verifying equipment interrupting ratings and SCCR on new or existing installations
• New construction, to confirm the installed equipment is correctly rated

What You Get

A short circuit study report showing the available fault current at each point in your system, an equipment evaluation identifying any device or assembly applied above its rating, and an updated one line diagram. The analysis is prepared under the responsible charge of a licensed Professional Engineer, with sealing as required by the applicable jurisdiction.

Part of a Complete Power System Study

A short circuit study is usually the first step in a larger power system study. The results feed directly into a protective device coordination study and an arc flash study. We can perform these analyses individually where appropriate, or together as part of a complete power system study.