WHAT IS A SHORT CIRCUIT AND SHORT CIRCUIT CURRENT?

A short circuit is an unintentional disruption of an electrical circuit resulting in a lower than normal resistance, allowing excessive current to flow. The excessive current is considered the short circuit current, or fault current.

Short circuit current is the amount of current that can flow to any given part of the electrical system in the event of a short circuit or fault. The short circuit current is derived from the utility source, generators, solar panels, or other power generation equipment.

WHAT IF THE EQUIPMENT IS NOT PROPERLY RATED FOR THE AVAILABLE SHORT CIRCUIT CURRENT?

Excessive short circuit currents may have destructive effects on inadequately rated electrical equipment. The equipment may fail and even explode when exposed to fault current over its rating, causing additional equipment and property damage, unplanned downtime, and possibly personal injury.

WHAT EQUIPMENT IS REQUIRED TO BE RATED FOR SHORT CIRCUIT CURRENT?

Protective devices such as circuit breakers and fuses require an AIC rating (Ampere Interrupting Capacity) which must be equal to or exceed the maximum short circuit current they may be subject to.

Electrical equipment such as Industrial control panels, HVAC equipment, MCC’s, elevator equipment, industrial machinery, etc. must have a sufficient SCCR (Short Circuit Current Rating) for where they are connected in the electrical system.

WHO REQUIRES THE EQUIPMENT TO BE RATED PROPERLY?

The National Electrical Code (NFPA-70) and Occupational Safety and Health Administration (OSHA) require electrical equipment to be adequately rated, and labeled accordingly.

HOW DO WE ENSURE THAT EQUIPMENT RATINGS ARE IN COMPLIANCE?

A short circuit analysis is necessary to calculate the available fault current at electrical equipment throughout a facility. Regardless of the date of installation or facility, a short circuit analysis is required to evaluate the ratings of the over-current protective devices and a variety of electrical equipment.

WHAT IS A SHORT CIRCUIT ANALYSIS?

A short circuit analysis is a study that calculates the available short circuit that could flow to electrical equipment in the event of a fault or short circuit. Knowing the available short circuit current will aid with the following:

Determine required interrupting rating for over-current protective devices.
Determine required short circuit current rating (SCCR) for equipment such as industrial control panels, HVAC equipment, industrial machinery and more.
Aid in the execution of protective device coordination study and arc flash incident calculations.
Label necessary equipment with short circuit current and calculation date.
Required when using NFPA-70E “Arc Flash PPE Category Method” to determine the necessary arc related PPE, in addition to meeting other parameters.

OUR PROCESS TO A COMPLETE SHORT CIRCUIT ANALYSIS

On-Site Data Collection & Field Verification

Collect necessary electrical data by licensed journeymen or master electricians. We will conduct visual inspections, remove equipment covers when necessary, and collect additional documentation from the customer to ensure a complete understanding of their electrical system.

Electrical System Modeling

Create one-line diagrams of the electrical distribution system with the latest and most popular software on the market.

Perform Comprehensive Short Circuit Calculations

Use the system model and computer aided software to perform ANSI Short Circuit Calculations.
Establish the required equipment short circuit ratings at all points in the electrical system.
Identify equipment in violation.
Label the required equipment with the calculated short circuit current to satisfy the code requirements.
Provide necessary documentation to the Authority Having Jurisdiction or local Electrical Inspector.

Provide Recommendations for Compliance

Provide recommended methods to bring the equipment into compliance by lowering the available short circuit current, or increasing the short circuit current rating.

Project Closeout