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© 2015 Eaton. All Rights Reserved..
1
Key 2014 NEC® Changes
Affecting Overcurrent
Protection
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Interconnected Electric Power Production Sources-Article 705Background Info
Example of a photovoltaic power sources in addition to the utility. Other sources
might include hydro, wind, PV, fuel cell, and on-site generator
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Alt. Energy Cable Limiters -705.31
New Requirement
Cable limiters or current limiting circuit breakers are required where the alternate
power sources are connected on the supply side of the service disconnecting means
and the conductors are greater than 10 feet in length, measured from the power
production source overcurrent protection.
Cable Limiter
Cable limiters or current limiting circuit breakers provide short-circuit protection for conductors
that are often unprotected. Easy solution where it is difficult to install an overcurrent protective
device within 10 feet of service conductors.
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Emergency Systems-Article 700- Background Info
Article 700 Emergency Systems
• “The provisions of this article apply to the electrical
safety of the installation, operation, and
maintenance”
• “Essential for safety of human life”
• Hotels
• Theaters
• Stadiums
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Emergency System Panelboard SPDs-700.8
New Requirement
“Surge Protection. A listed SPD shall be installed in or on all emergency systems
switchboards and panelboards.”
Provides surge protection for critical, life-safety-related loads
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6
Definition of Selective Coordination-Article 100Background Info
Without Selective Coordination
Loads Unnecessarily Lost
With
Coordination
WithSelective
Selective
Coordination
Overcurrents are isolated by only one
No Unnecessary
Load Lost
Blackouts
deviceNo Unnecessary
Loads
OPENS
Opens
Fault
NOT
AFFECTED
Fault
Not Affected
Unnecessary Power Loss
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Definition of Selective Coordination-Article 100
Modified Definition
“Coordination (Selective). Localization of an overcurrent condition to restrict outages to the
circuit or equipment affected, accomplished by the choice selection and installation of
overcurrent protective devices and their ratings or settings for the full range of available
overcurrents, from overload to the maximum available fault current, and for the full range of
overcurrent protective device opening times associated with those overcurrents.”
X
Selective coordination cannot “stop” at 0.1 or 0.01 seconds. The definition of
“Selective Coordination” now clearly covers all available overcurrents (overloads and
short circuits) and all times associated with those overcurrents.
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Selective Coordination-Enforcement
New Requirements
“Selective Coordination shall be selected by a licensed professional engineer or other
qualified persons engaged primarily in the design, installation, or maintenance of electrical
systems. The selection shall be documented and made available to those authorized to
design, install, inspect, maintain, and operate the system.”
New for elevators (620.62), emergency (700.28), legally required standby
(701.27), and critical operations power systems (708.54)
Requirements added to clarify who can design the selectively coordinated system. The
responsible party for the selection is required to provide documentation for the OCPD types,
ampere ratings, and settings so the circuits can be inspected, installed, and maintained. This
will make it easier for AHJs to enforce selective coordination.
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9
Critical Operations Data Systems-Article 645Background Info
• Information technology equipment system
• Continuous operation required
•
public safety
•
emergency management
•
national security
•
business continuity
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Critical Operations Data Systems-645.27
New Requirement
“Selective Coordination. Critical Operations Data System(s) overcurrent devices shall be
selectively coordinated with all supply side overcurrent protective devices.”
OPENS
NOT
AFFECTED
Fault
New requirement will help ensure that unnecessary outages to the entire or large parts of a
critical operations data system do not occur for overcurrents in a small portion of the electrical
distribution system, such as an individual rack.
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Healthcare Selective Coordination 517.30(F)
Modified Requirement
“(F) Selective Coordination. Overcurrent protective devices serving the essential
electrical system shall be selectively coordinated for the period of time that a fault’s
duration extends beyond 0.1 second.
Informational Note: The terms “Coordination” and “Coordinated” as used in this
section do not cover the full range of overcurrent conditions.”
Healthcare inspectors should, at minimum, check to assure
“coordination” to 0.1 seconds for the entire essential electrical system.
Many of the circuits found in healthcare’s essential electrical systems
must be “selectively coordinated” in commercial/institutional
construction for all possible overcurrents and opening times
associated with those overcurrents.
This change clarifies that the healthcare requirement for coordination at 0.1 seconds and
greater is different than the requirement for selective coordination in Sections 620.62, 645.27,
700.28, 701.27, and 708.54.
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12
Arc-Flash Reduction-240.87-Background Info
• Arc-Flash mitigation techniques
• Necessary because of increased arc-flash incident energy when
large CBs are intentionally delayed.
• 2011 NEC® was unclear with loopholes that allowed some to avoid
compliance
240.87 of 2011 NEC® was saving lives but needed tighter requirements
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Arc-Flash Reduction-240.87
Modified requirement
• Requires all CBs, 1200 amperes and above, to include
means to reduce arc-flash incident energy
•
ZSI, Differential Relaying, ARMS, Active Mitigation, Approved Equivalent
Modified requirement closes loopholes, providing safer work environments
for workers. It is the biggest single improvement to worker arc-flash safety
since the addition of arc-flash requirements in the NEC® and NFPA70E.
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