Understanding selective coordination and coordination in the 2014 NEC®
As part of NFPA 70, Selective coordination is not new to the National Electrical Code, 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 NFPA 70 - 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.
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.
Find out how easy coordination and selective coordination can be with Eaton’s Selective Coordination Designer v1.0.
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Eaton is the only manufacturer that offers both fuse and circuit breaker solutions. This includes tested combinations of Bussmann series fuses with upstream Eaton circuit breakers that provide designers greater flexibility in creating efficient selective coordination solutions for their projects.
We also offer technical expertise and a support structure to help achieve your project goals, whether facing new construction, expansion or renovation.
Selective coordination tables of tested fuse to upstream fuse and fuse to upstream circuit breakers for use in achieving selective coordination in a building's electrical system.