Short-Circuit Current Ratings

Code and agency requirements

Why is SCCR important?

It’s about safety. Both the NEC and OSHA requirements for SCCR prohibit having any equipment located at a point in an electrical system where the available short-circuit current is greater than what the equipment can withstand. This applies to installations of new equipment, as well as equipment that’s moved around within a single or multiple facilities.

Proper short-circuit protection for components is required by NEC®

  • Overcurrent protective devices, such as fuses and circuit breakers, must have suitable interrupting ratings for the available fault current where the equipment is installed (NEC 110.9).
  • Components that provide functions other than overcurrent protection, such as disconnects, power distribution blocks, motor controllers and others, are required to achieve adequate Short-Circuit Current Rating (SCCR) (NEC 110.10).

Proper short-circuit protection for control panels on equipment is required by NEC

  • Equipment and machinery must be marked with its SCCR (NEC 409.110, 440.4(B), 670.3)
  • Equipment must not be installed where the available fault current exceeds its SCCR marking (409.22)

View this video on 2017 NEC Changes Eaton's Guide to SCCR Compliance to see the Eaton advantage in meeting the 2017 National Electric Code Changes as it relates specifically to Short-Circuit Current Ratings.

UL 508A Supplement SB defines a procedure for determining the equipment SCCR

  • Applying component SCCRs (SB4.2)
  • Applying feeder components (SB4.3)
  • Determining the overall equipment SCCR (SB4.4)

2017 NEC Code changes specific to Short-Circuit Current Ratings (SCCRs)

What can happen when equipment SCCR is too low?

View the video below and see for yourself.

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Solving SCCR challenges

How much fault current protection do I need?

Bussmann series FC2 Available Fault Current Calculator is the online and mobile app makes it easy to calculate fault current levels and generates NEC® 110.24 compliant labels and one-line diagrams. Knowing available fault current is vital for compliance with NEC and OSHA SCCR requirements. This free mobile (Apple and Android devices) can be downloaded at the app store, or use the web-based version.

Watch this video to see how easy it is to ues.

What is my control panel's SCCR?

Bussmann series OSCAR™ SCCR online compliance software easily guides subscribers through entering an electrical panel’s components to calculate the equipment SCCR, provide a one-line diagram and provide detailed documentation.  This online application is a quick and accurate means for compliance with 2017 NEC and UL 508A Supplement SB equipment SCCR marking requirements. Request a free 7-day trial.

How do I fix weak links?

The SCCR Protection Suite provides OEM designers easy access to a comprehensive product portfolio of circuit protection and wiring distribution/termination/switching devices - and their component SCCRs - to meet SCCR needs up to 200kA.

Application notes and literature

Gain insight into this often misunderstood subject and how you can plan and implement an effective SCCR strategy.

High SCCR Bussmann series products

Fused disconnects

Power distribution fuse blocks

Power distribution blocks

Modular Fuse blocks and holders

Solution center

Useful tools for electrical applications with software programs to simplify system calculations, presentations on important topics and system specifications.

Achieving code compliance for short-circuit protection

First: Know the available fault current in your facility where equipment is installed

Eaton offers two solutions to help solve this need:

  • Bussmann series FC2 Available Fault Current Calculator is the online and mobile app makes it easy to calculate fault current levels and generates NEC® 110.24 compliant labels and one-line diagrams. Knowing available fault current is vital for compliance with NEC and OSHA SCCR requirements. This free mobile (Apple and Android devices) can be downloaded at the app store, or use the web-based version. Watch this video to see how easy it is to ues.
  • For a comprehensive fault current study, Eaton’s Electrical Engineering Services and Systems (EESS) provides a portfolio of services, including fault current analysis and documentation. For more information or to request an initial consultation, call toll-free 855-BUSSMANN (855-287-7626).

Second: Specify your equipment SCCR requirements with suppliers and installers.

  • The equipment SCCR must be equal to or greater than the available fault current at the location where the equipment is installed. Consider future events that may affect the available fault current where the equipment is installed, such as relocating equipment to where the fault current is higher, or distribution equipment changes that may raise the fault current, such as busway installation or transformer replacement. For additional training, help or support in defining SCCR requirements, call toll-free 855-BUSSMANN (855-287-7626) or email FuseTech@eaton.com.

Third: Leverage available resources to help verify proper application

  • Require documented SCCR analysis to validate ratings. Surveys indicate that many design engineers struggle when interpreting SCCR procedure and locating SCCR information.  Eaton provides resources that assist engineers with calculating and documenting equipment SCCR and locating components that address SCCR weak links.
  • Contact Eaton for free training and analysis support. Eaton provides free training for purchasers and manufacturers of industrial equipment and machinery.  Eaton also provides a free SCCR analysis. For more information, call toll-free 855-BUSSMANN (855-287-7626) or email FuseTech@eaton.com.

Application notes and literature

Gain insight into this often misunderstood subject and how you can plan and implement an effective SCCR strategy.