Service
Short Circuit Analysis
Available fault current at every bus, checked against the interrupting and withstand ratings of the equipment it feeds. Nothing in your system should be applied above its rating.
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What is a short circuit analysis?
A short circuit analysis calculates the maximum fault current available at each point in your electrical system. We model the utility contribution, transformers, cables, and motor contribution, then compute bolted three-phase and line-to-ground fault current at every bus.
Those numbers get compared against the interrupting rating of every breaker and fuse and the withstand rating of every bus. Equipment applied above its rating is a code violation, and it is a physical problem too: a breaker asked to interrupt more current than it was tested for can fail instead of clearing. The same fault current results feed your arc flash and coordination studies.
What you receive
Fault current table
Bolted fault current at every bus, three-phase and line-to-ground.
Device rating check
Interrupting and withstand ratings against available fault current, with pass/fail flags.
Field-verified one-line
Drawn to your equipment tags with conductor and transformer data.
110.24 marking data
Available fault current and calculation date, ready to field-mark on service equipment.
Native model files
SKM model released to you for future studies.
Get this study scoped
Send a one-line or a device count. Fixed-fee proposal in two business days.
Get a Fixed-Fee Proposalor call (571) 310-6945Why it’s required
Equipment must have an interrupting rating sufficient for the available fault current, and the system must be selected to withstand it.
Service equipment must be field-marked with the maximum available fault current and the date of the calculation, and the calculation reverified when the system is modified.
Utility upgrades and new transformers raise available fault current. A study from before those changes can leave equipment under-rated for years without anyone noticing.
Our process
Scoping & fixed-fee proposal
Send a one-line or panel schedule; we scope and price the study in two business days.
Field data collection
We record equipment ratings, conductor sizes and lengths, and confirm the utility available fault current.
Modeling & analysis
We build the model, calculate fault current at every bus, then check every device rating against it.
PE review & report
A licensed PE reviews and seals the results, with clear flags on anything under-rated.
Turnaround & pricing
Bundled pricing applies when this runs with an arc flash or coordination study on the same model. Use the pricing calculator
Short Circuit Analysis FAQ
No, but it comes first. A short circuit study answers how much fault current is available and whether equipment is rated for it. An arc flash study uses that current, plus device clearing times, to calculate incident energy. You cannot do the second without the first.
NEC 110.24 requires service equipment to be field-marked with the maximum available fault current and the date the calculation was done. When the system is modified in a way that changes that value, the calculation has to be reverified and the marking updated. We supply the calculation and the marking.
AIC is the ampere interrupting capacity of a breaker or fuse — the maximum fault current it was tested to interrupt safely. It is stamped on the device or its nameplate. If available fault current at that location exceeds the AIC, the device is misapplied under NEC 110.9.
It may not clear the fault. Instead of interrupting, the device can fail internally, which turns a clearing operation into an arcing fault inside the enclosure and pushes the problem upstream. It is also a straightforward NEC 110.9 violation that shows up in insurance and AHJ reviews.
We request it from your utility in writing, as available fault current or source impedance at the service point. Utilities often give a conservative maximum. We model with that value and note it as an assumption, because it drives every downstream result in the study.
Yes. A larger transformer, a new service, or a utility system change alters available fault current at the service and everything downstream. Equipment that passed under the old numbers can be under-rated under the new ones, and NEC 110.24 marking has to be reverified.
Especially then. Older gear often carries lower interrupting ratings, and decades of utility reinforcement and transformer replacements push available fault current the other direction. That combination is where we most often find devices applied above their rating. Nothing about the equipment looks different, which is exactly why it goes unnoticed.
The definitive number comes from a short circuit study built on your utility’s source contribution and your system impedances. Your utility can quote fault current at the service point on request; everything downstream requires calculation. NEC 110.24 requires service equipment to be field-marked with the value.
Interrupting rating is the maximum fault current a breaker or fuse can safely stop. Withstand rating is the fault current a bus or enclosure can survive until an upstream device clears. Both must exceed the available fault current at their location under NEC 110.9 and 110.10.
Ready to scope your short circuit analysis?
A 10-minute call with a licensed PE — we'll tell you what your study should cover and what it should cost. No obligation.