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Selective coordination

Understanding Selective Coordination and Coordination in the 2014 National Electric Code (NEC)
Selective coordination is not new to the NEC, but the interpretations and enforcement of it have varied. The NEC 2014 clearly defines two distinct levels of coordination; Selective Coordination for all currents and times and Coordination to 0.1 seconds.

Selective coordination is required for systems related to life safety (as defined in the NEC), and is achieved when an overcurrent on a circuit is interrupted and only the closest upstream device opens such that only the section of the electrical system with a problem is taken offline. Selective coordination applies for the full range of overcurrent on the system and the full range of overcurrent interrupting times associated with those overcurrents.

Coordination is required for over current protective devices for Essential Electrical Systems in healthcare facilities. The overcurrent protective devices must be coordinated for any fault time extending beyond 0.1 seconds. Essential Electrical Systems are comprised of life safety branch, critical branch, and equipment branch.

Eaton offers the broadest circuit protection and electrical safety solutions in the industry, enabling customers to achieve code compliance more effectively and economically. What’s more, we offer technical expertise and a support structure to help achieve your project goals, whether facing new construction, expansion or renovation. We offer a full range of circuit protection products that will help meet selective coordination requirements in multiple applications in a cost-effective manner. Eaton also offers customer support, making sure the right product is provided for your application.

SCD Tool

Easy to understand, not always easy to achieve

There are many device and system attributes that must be considered.

Once defined, a selectively coordinated solution must be found between system devices according to manufacturer time-current-curves and selective coordination tables.

Devices must also be verified per their assembly placement and conductor allowance.

Often, it’s necessary to adjust system attributes to accommodate the selected devices.

When this occurs, the system must be re-analyzed, and the process starts over again.

This process can make it difficult to determine a system solution.

Online help is here - SCDv1.0

Eaton's Selective Coordination Designer v1.0 is a powerful online tool to help you identify and select coordination solutions.

Now, at your fingertips, SCDv1.0 uses cutting-edge functionality for:

  • Displaying a one-line circuit diagrams
  • Compiling a list of all viable solutions for selected devices
  • Pinpointing the solutions for the selected devices and assemblies
  • Estimating conductor sizes, if unknown
  • Calculating fault currents, if unknown
  • Exporting the results to pdfs

With this tool, you can select from today’s broad variety of overcurrent solutions that better address important safety, equipment protection, reliability and efficiency considerations.