Short Circuit Analysis
Fault-duty calculations to verify equipment ratings, identify overstressed gear, and support safe, reliable operation of your power distribution system.
Short circuit studies verify that your equipment is adequately rated for the fault currents that can occur on the system. We identify weak points before they become failures.
What Is Short Circuit Analysis?
Short circuit analysis calculates the maximum and minimum fault currents that can flow through your electrical system at various points, given:
- Utility or generator sources
- Transformer impedances
- Cable and busway impedances
- Motor contributions
These calculated currents are compared to the interrupting and withstand ratings of:
- Switchgear and switchboards
- Panelboards and MCCs
- Breakers and fuses
- Busway, feeders, and other key components
If available fault current exceeds equipment ratings, there is a risk of catastrophic failure during a fault, with potential damage to equipment and safety risks to personnel.
When A Short Circuit Study Is Needed
Typical triggers:
- New construction or major service upgrades
- Replacement of main switchgear or switchboards
- Addition of large motors, generators, or transformers
- Utility short-circuit data changes
- Existing gear has unknown or marginal ratings
- Preparation for an arc flash study (short circuit is a prerequisite)
Our Process
1. Define the system scope and voltage levels
2. Collect equipment ratings and impedance data from drawings and field surveys
3. Build or update the short circuit model
4. Calculate three-phase and, when required, line-to-ground fault currents
5. Compare results to available equipment ratings
6. Document overstressed equipment and recommended corrective actions
What We Need From You
- Utility available fault current or coordination with the serving utility
- One-line diagrams and equipment schedules
- Nameplate ratings where drawings are incomplete
- Access for field verification of major gear
What We Need From You
- Utility available fault current or coordination with the serving utility
- One-line diagrams and equipment schedules
- Nameplate ratings where drawings are incomplete
- Access for field verification of major gear
Codes And Standards
- NEC requirements for equipment short-circuit current ratings
- IEEE standards for short circuit calculations and modeling
- NFPA 70E and IEEE 1584, where short circuit values feed into arc flash analysis
FAQs
Q: Can a short circuit study be done without an arc flash study?
Yes. Short circuit analysis is a standalone requirement to confirm equipment ratings, but it is also a foundational step for arc flash analysis.
Q: What happens if equipment is underrated?
We will identify those locations and provide recommendations such as replacement, addition of current-limiting devices, or reconfiguration to reduce available fault current.