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1
Selective Coordination
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Summary of Requirements: Selective Coordination
Key Selective Coordination requirements
• Art.100
Definition: Coordination (Selective)
• 517.30(F) Coordination for Healthcare
• 620.62
Elevator Circuits
• 645.27
Critical Operations Data Systems (New for 2014)
• 700.28
Emergency Systems
• 701.27
Legally Required Standby Systems
• 708.54
Critical Operations Power Systems (COPS)
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33
Selective Coordination System Prospective
Without Selective Coordination
Loads Unnecessarily Blacked Out
With Selective Coordination
No Unnecessary Load Blackouts
OPENS
Opens
Fault
NOT
AFFECTED
Fault
Not Affected
Unnecessary Power Loss
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4
4
Selective Coordination System
To achieve selective
coordination for electrical
systems requires engineering
analysis and proper overcurrent
protective device selection
For most electrical systems,
selective coordination is a
desirable design consideration
For some electrical systems,
selective coordination is
mandatory (limited number of
building types and then usually only a
few circuits)
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With Selective Coordination
No Unnecessary Load Blackouts
OPENS
NOT
AFFECTED
Fault
5
5
Selective Coordination Requirements
Why?
• Increases system reliability to deliver
power
• Focus on the load!
Availability of power to vital loads as
long as possible
• Life Safety
• Public safety and national security
(COPS)
• Increases system reliability to power
vital loads even during emergencies
and disasters
• Facilitates restoration of power to
affected loads
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Fault
OPENS
NOT AFFECTED
66
Code Panel Statements Provide the Reason
Code Panel 13 Statement (700.27) Proposal 13-135 2008
NEC:
“…Selective coordination increases the reliability of the
emergency system”
Code Panel 20 Statement (708.54) Comment 20-13 2008
NEC:
“The overriding theme of Articles 585 (renumbered to 708)
is to keep the power on for vital loads. Selective
coordination is obviously essential for the continuity of
service required in critical operations power systems.
Selective coordination increases the reliability of the COPS
system.”
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77
Selective Coordination Includes the
Entire Circuit Path, Thru Both Sources
Normal
Source
1. From a vital load to the alternate
source, the OCPDs shall be
selectively coordinated
Alternate
Source
N
E
ATS
Panel
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88
Selective Coordination Includes the
Entire Circuit Path, Thru Both Sources
1. From a vital load to the alternate
source, the OCPDs shall be
selectively coordinated
Normal
Source
2. From a vital load to the normal source
main, the emergency system OCPDs
shall be selectively coordinated with
all upstream devices
“Emergency system(s) overcurrent
devices shall be selectively coordinated
with all supply side overcurrent protective
devices”
This wording is inclusive of the normal
source path OCPDs
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Alternate
Source
N
E
ATS
Panel
99
Definition of Selective Coordination-Article 100
Definition Change for 2014 NEC®:
“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
Definition now clearly covers all available overcurrents and all times associated
with those currents. It’s all or nothing. Can’t be selectively coordinated just for
times greater than 0.1 or 0.01 seconds.
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10 10
Selective Coordination Requirements
Article 620 Elevators
620.62 Selective Coordination
Where more than one driving machine
disconnecting means is supplied by a single
feeder, the overcurrent devices in each
disconnecting means shall be selectively
coordinated with any other supply side
overcurrent protective devices.
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11 11
Selective Coordination Requirements
• NEC 620.62 Elevator Circuits (since 1993)
• Requires selective coordination on circuit
paths when multiple elevators are on a
feeder. Required to ensure safety of human
life especially during emergency egress
• Purpose of this requirement?
• Maximize continuity of service
• Quicker restoration of power
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12 12
NEC 620.62 Elevator Circuits
Selective Coordination
Single Feed to
Multiple Elevators
M1
Main Disconnect /
Over Current
Protective Device
Feeder
Disconnects/
OCPDs
F2
B1
B2
B3
E1
E2
E3
Passenger Elevators
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Branch
Disconnects /
OCPDs
F4
B4
E4
Service Elevator
13
13
Selective Coordination (NEC)
Article 700 Emergency Systems
700.28 Selective Coordination.
Emergency system(s) overcurrent devices
shall be selectively coordinated with all
supply side overcurrent protective devices
(Wording for 701.27 and 708.54 is similar except for the
type system)
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14 14
Critical Operations Data Systems-645.27
New requirement in 2014 NEC
“Selective Coordination. Critical Operations Data System(s) overcurrent
devices shall be selectively coordinated with all supply side overcurrent
protective devices.”
A Critical Operations Data System is an information technology equipment system that
requires continuous operation for reasons of public safety, emergency management, national
security, or business continuity.
New requirement for Critical Operations Data Systems will help ensure that
entire critical computer systems do not crash due to a minor problem in one
rack or server.
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15 15
Healthcare Selective Coordination 517.30(F)
Modified requirement for 2014 NEC®:
“(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 life safety branch of the essential electrical system.
These same circuits in commercial buildings must be “selectively
coordinated” 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, 700.28, 701.27, and 708.54.
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16 16
How
to Achieve
Selective Coordination
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17 17
Lack of Selective Coordination
CURRENT IN AMPERES
• Many people
mistakenly assume that
a lower ampere rated
circuit breaker will
always open before a
larger ampere rated
circuit breaker
• Where the circuit
breakers cross, they
are typically not
selectively coordinated.
1000
800A
30A MCCB 18kAIR
100
800
200A MCCB 35kAIR
X
800A MCCB 35kAIR
30A
30
X
1
0.10
0.01
TIME IN SECONDS
200
10
200A
0.1
0.01
10
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100
1K
10K
100K
18
30 200 800 MCCB.tcc Ref. Voltage: 480 Current in Amps x 1 30 200 800 18
MCCB.drw
How to Selectively Coordinate?
How to Selectively Coordinate with Circuit Breakers?
• Do short-circuit current study and coordination study
investigating various types and options of CBs for specific
project
1.
2.
Coordination Study & resolve
any non-coordination issues
CURRENT IN AMPERES
1000
10
2
3 4 5 6 7 89 100
2
CURRENT IN AMPERES AT 480 VOLTS
3 4 5 6 7 89 1000 2 3 4 5 6 7 89 10000 2
1000
700
700
500
400
300
500
400
300
800A
200
Short-Circuit Current Study
3 4 5 6 7 89 100000
30A MCCB 18kAIR
200
100
100
70
70
50
40
30
50
40
30
By
1000
200A
20
20
10
10
7
7
100
200A MCCB 35kAIR
800A MCCB 35kAIR
30A
5
4
3
5
4
3
2
2
1
1
.7
.7
.5
.4
.3
.5
.4
.3
.2
.2
.1
.1
.07
.07
.05
.04
.03
.05
.04
.03
.02
.02
TIME IN SECONDS
TIME IN SECONDS
Ace Engineering
TIME IN SECONDS
10
1
0.10
0.01
.01
10
2
3 4 5 6 7 89 100
2
3 4 5 6 7 89 1000 2
3 4 5 6 7 89 10000 2
CURRENT IN AMPERES AT 480 VOLTS
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3 4 5 6 7 89 100000
10
100
1K
10K
100K
.01
30 200 800 MCCB.tcc Ref. Voltage: 480 Current in Amps x 1 30 200 800 MCCB.drw
19 19
Circuit Breaker Selective Coordination Alternatives
Circuit Breaker Options (next slides)
1. Instantaneous trip (IT)
Circuit Breaker Type
MCCB
ICCB
LVPCB
2. Instantaneous trip, coordination tables
3. Fixed high magnetic IT
4. Short time delay (STD) w/ IT override
(MCCB/ICCB)
5. Short time delay (STD) w/o IT override
(LVPCB)
Note: some options may require larger frame
or different type CBs
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20 20
1. Circuit Breaker Instantaneous Trip
2
CURRENT IN AMPERES AT 480 VOLTS
3 4 5 6 7 8 9 100
2 3 4 5 6 7 8 9 1000 2 3 4 5 6 7 8 9 10000 2
700
200A
X
30A
X
100
50
40
30
200
100
70
50
40
30
20
20
10
10
7
7
5
4
3
5
4
3
2
30A
2
1
1
.7
.7
.5
.4
.3
.5
.4
.3
.2
.2
.1
Up to
7600A
Up to
1500A
500
400
300
200A
IT = 10X
70
TIME IN SECONDS
800A
200
1000
700
800A
IT = 10X
500
400
300
Up to where the circuit
breakers cross, it is
interpreted to be
coordinated. See
3 4 5 67
0.1s
.1
.07
.07
.05
.04
.03
.05
.04
.03
.02
.02
.01
0.01s
4 5 6 7 8 9 10
TIME IN SECONDS
1000
4 5 6 7 8 9 10
2
3 4 5 6 7 8 9 100
2
3 4 5 6 7 8 9 1000 2
3 4 5 6 7 8 9 10000 2
3 4 5 67
.01
CURRENT IN AMPERES AT 480 VOLTS
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1500A
7600A
21 21
2. CB Manufacturer’s
Selective Coordination Table
Table illustrates the selection of molded case CBs
to achieve selective coordination
22
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22
2. CB Manufacturer’s
Selective Coordination Table
Example:
30A & 200A MCCBs
1500A Crossing Point
Interpreting Curves
Max. 2700A: CB Mfg.
Coordination Testing
2
CURRENT IN AMPERES AT 480 VOLTS
3 4 5 6 7 8 9 100 2 3 4 5 6 7 8 9 1000 2 3 4 5 6 7 89 10000 2
3 4 5 67
700
1000
700
800A
500
400
300
200
500
400
300
200
100
200A
70
TIME IN SECONDS
CB Manufacturer’s
Coordination Tables can
help show coordination for
higher fault current than
simply plotting curves
4 5 6 7 89 10
100
70
50
40
30
50
40
30
20
20
10
10
7
7
5
4
3
5
4
3
2
2
30A
1
1
.7
.7
.5
.4
.3
.5
.4
.3
.2
.2
.1
TIME IN SECONDS
1000
0.1s
.1
.07
.07
.05
.04
.03
.05
.04
.03
.02
.02
.01
0.01s
4 5 6 7 89 10
2
3 4 5 6 7 8 9 100
2
3 4 5 6 7 8 9 1000 2
3 4 5 6 7 89 10000 2
3 4 5 67
.01
CURRENT IN AMPERES AT 480 VOLTS
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23 23
3. Coordination
Fixed High Magnetic CB
Fixed High Magnetic
Instantaneous Trip
 Not adjustable IT
 High IT setting
 Introduced to help achieve
selective coordination
 First started seeing these
for circuits supplying
critical loads such as data
centers and financial
centers
20X
17X
24
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24
3. Coordination
Fixed High Magnetic CB
1000
4 5 6 7 8 9 10
2
CURRENT IN AMPERES AT 480 VOLTS
3 4 5 6 7 8 9 100 2 3 4 5 6 7 8 9 1000 2 3 4 5 6 7 8 9 10000 2
3 4 5 67
700
1500A crossing point
standard adjustable IT CB
3200A crossing point
fixed high magnetic CB
700
800A
500
400
300
500
400
300
200
200
100
100
70
70
50
40
30
20
20
10
10
7
7
5
4
3
5
4
3
2
2
1
30A
1
.7
.7
.5
.4
.3
.5
.4
.3
.2
.2
.1
0.1s
.1
.07
.07
.05
.04
.03
.05
.04
.03
.02
.02
.01
0.01s
4 5 6 7 8 9 10
TIME IN SECONDS
200A
50
40
30
TIME IN SECONDS
The 200A CB is a fixed
high magnetic
instantaneous trip (IT)
device. It will coordinate
with the downstream 30A
CB up to 3200A versus
1500A for a conventional
200A CB.
1000
2
3 4 5 6 7 8 9 100
2
3 4 5 6 7 8 9 1000 2
3 4 5 6 7 8 9 10000 2
3 4 5 67
.01
CURRENT IN AMPERES AT 480 VOLTS
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25 25
4. Coordination STD with IT Override
Insulated
case CB with
short-time delay (STD) and
instantaneous override
(protects CB)
Short-time
delay improves
coordination from 7,600A
(slide 21) to 12,000A
Coordinated in shortcircuit region above 12,000A
due to instantaneous
override
800A
200A
Not
0.1s
0.01s
26
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12,000A
26
5. Short-Time Delay (No Instantaneous Override)
1000
3 4 5 6 7 8 9 100
2
CURRENT IN AMPERES AT 480 VOLTS
3 4 5 6 7 8 9 1000 2 3 4 5 6 7 8 9 10000 2
3 4 5 6 7 8 9 100000
1000
700
500
400
300
500
400
300
800A
200
200
100
100
70
70
50
40
30
50
40
30
200A
20
20
10
10
7
7
30A
5
4
3
5
4
3
2
2
1
1
.7
.7
.5
.4
.3
.5
.4
.3
.2
.2
.1
0.1s
.1
.07
.07
.05
.04
.03
.05
.04
.03
.02
.02
.01
0.01s
10
2
3 4 5 6 7 8 9 100
2
3 4 5 6 7 8 9 1000
27 2
3 4 5 6 7 8 9 10000 2
3 4 5 6 7 8 9 100000
CURRENT IN AMPERES AT 480 VOLTS
© 2015 Eaton. All Rights Reserved..
27
.01
TIME IN SECONDS
Plot curves to ensure
there is no crossing of
curves. Must have time
settings with enough
separation.
2
700
TIME IN SECONDS
Selective coordination for
all overcurrents up to the
interrupting rating for each
circuit breaker
10
Lack of Selective Coordination
CURRENT IN AMPERES
1000
100
100A Fuse
TIME IN SECONDS
• Many people mistakenly
assume that a lower
ampere rated fuse will
always open before a larger
ampere rated fuse
D
100A
45A Fuse
• If fuse curves cross, larger
upstream fuse and
downstream fuse can both
open for overcurrents on the
loadside of 45A fuse
(not selectively coordinated)
10
100A
45A
45A
1
0.10
0.1s
0.01
0.01s
10
100
1K
tcc1.tcc Ref. Voltage: 480 Current in Amps x 1
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10K
28 28
Selective Coordination with Fuses
How to Selectively Coordinate with Fuses?
Answer:
Follow the Fuse Manufacturer’s Selectivity
Ratio
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29 29
Fuse Time Current Curves
 For operation of upstream
fuse in less than 0.01
seconds (Isca greater than
red arrow)
 Use fuse manufacturer’s
selectivity ratios
0.1
0.01
30
2005 SPD p.90
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30
Selective Coordination
Line Side Fuse
Load Side Fuse
LOW-PEAK® : LOW-PEAK®
2:1 Line:Load Ratio
No plotting required!
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31 31
Fuse Selectivity Ratio Example 1
Low-Peak®
KRP-C-800SP
Loadside Fuse
Low-Peak®
KRP-C_SP
LPJ_SP
KRP-C_SP
2:1
2:1
LPJ_SP
-
2:1
LPJ-400SP
Low-Peak®
LPJ-100SP
Overloads or faults
of any level up to
200,000A
400/100= 4:1 only 2:1 needed
Selective Coordination achieved
between these two fuses
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32 32
Fuse Selectivity Ratio Example 1
Circuit Path Selectively
Coordinated
Loadside Fuse
Low-Peak®
KRP-C-800SP
KRP-C_SP LPJ_SP
Low-Peak
LPJ-400SP
Low-Peak
LPJ-100SP
KRP-C_SP
2:1
2:1
2:1
LPJ_SP
-
2:1
800/400 = 2:1 only 2:1 needed
Selective Coordination achieved
Overloads or faults 400/100= 4:1 only 2:1 needed
Selective Coordination achieved
of any level up to
between these two fuses
200,000A
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33 33
Fuse Selectivity Ratio Example 2
• What about branch circuit lighting panel applications?
Low-Peak
KRP-C-800SP
Low-Peak
LPJ-200SP
Low-Peak CUBEFuse
TCF20RN
Branch circuits:
CCPB disconnect
with CUBEFuse
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34 34
Fuse Selectivity Ratio Example 2
Loadside Fuse
Low-Peak
KRP-C-800SP
KRP-C_SP LPJ_SP TCF20RN
Low-Peak
LPJ-200SP
KRP-C_SP
2:1
2:1
2:1
LPJ_SP
-
2:1
2:1
Low-Peak CUBEFuse
TCF20RN
Overloads or faults of
any level up to
200,000A
200/20= 10:1 only 2:1 needed
Selective Coordination achieved
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35 35
Fuse Selectivity Ratio Example 2
Circuit path
selectively coordinated
Loadside Fuse
KRP-C_SP LPJ_SP TCF20RN
Low-Peak
KRP-C-800SP
Low-Peak
LPJ-200SP
Low-Peak CUBEFuse
TCF20RN
Overloads or faults of
any level up to
200,000A
KRP-C_SP
2:1
2:1
2:1
LPJ_SP
-
2:1
2:1
800/200 = 4:1 only 2:1 needed
Selective Coordination achieved
200/20= 10:1 only 2:1 needed
Selective Coordination achieved
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36 36
Selective Coordination – CB to Fuse
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37
NEW Selective Coordination Tool
Selective Coordination Designer v1.0
•
•
•
•
•
100% selective coordination plus 0.1, and 0.01 second coordination
Configurable up to 6 device levels
Identifies assembly options
Suggests optimal solution
Eliminates extensive researching and multiple trial and error iterations
Available at
eaton.com/bussmannseries
Click on “Resources”
Click on “Education”
Click on “Solution Center
Library”
Click on “Selective
Coordination”
Click on “Online Selective
Coordination Designer
v1.0 tool”
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38
Selective Coordination Fuses & CBs
Summary
• It is possible to meet the selective coordination
requirements with fuse systems, circuit breaker
systems, or combination CB/fuse systems
• For fuse systems, comply with the fuse manufacturer’s
selectivity ratios
• For circuit breaker systems, comply with the circuit
breaker manufacturer’s selectivity tables (and review
selective coordination study).
• For systems utilizing both fuses and circuit breakers,
comply with the manufacturer’s selectivity tables.
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39 39
Enforcement
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Selective Coordination-Enforcement
New requirements for 2014 NEC®:
“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.
This will make it easier for AHJs to enforce selective coordination.
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41 41
Selective Coordination
Ensuring Compliance
Plan Review and Inspection
 Designer provides documentation verifying
selective coordination
 Site inspection verifies correct devices to
achieve selective coordination are
installed per plans
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42 42
Additional Selective Coordination Information
• Aids in understanding and how to
• SPD Electrical Protection Handbook (37 pages on
selective coordination)
• Go to eaton.com/bussmannseries
• Click on “Resources”
• Click on “Library”
• Click on “Selecting Protective Devices Handbook”
• Choose between clicking on “Access interactive online
version” and “Download PDF”
• Other information such as articles by industry experts
and more
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43 43
IAEI Article
IAEI Article “Selective coordination
restricts outages to the circuit or
equipment affected, ensuring reliability of
electrical power”
By Mark Hilbert
Former Chief Electrical Inspector for the
State of New Hampshire Bureau of
Electrical Safety and Licensing
Go to
eaton.com/bussmannseries
Type “Hilbert” into the Google search
engine
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44 44
NEC Digest (NFPA Publication)
NEC Digest article “Keep the
Power On For Vital Loads”
By Evangelos Stoyas P.E.,
recently retired Chief of the
Power Reliability Enhancement
Program in the Special Missions
Office at Fort Belvoir, Virginia. He
was a member of CMP-20, which
developed the new Article 708
Critical Operations Power
Systems
Go to eaton.com/bussmannseries
Type “Stoyas” into the Google
search engine.
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45 45
Selective Coordination Check List
• AHJ checklist available at
• eaton.com/bussmannseries
•
Click on “Resources”
• Click on “Education”
• Click on “Solution Center”
• Click on “Electrical Inspector Tools”
• Click on “Selective Coordination
Requirements Checklist”
• Choose either “PDF” or Word doc”
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46 46
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47