SHORT CIRCUIT CURRENT RATINGS
VTAC 9 AC Drive
NATIONAL ELECTRIC CODE INTRODUCES ARTICLE 409 FOR INDUSTRIAL CONTROL PANELS:
In 2005, the national Electric Code (NEC) introduced Article 409 for Industrial Control Panels requiring that panel
builders and original equipment manufacturers (OEM) analyze and mark their panels with short circuit current
ratings (SCCR).
WHY ARTICLE 409 WAS DEVELOPED:
Historically, industrial control panels have been evaluated under several different NEC articles, which have led to
inconsistencies. Article 409 provides common construction and installation requirements. It also establishes a
marking requirement for short circuit current ratings of industrial control panels. Equipment installed where fault
current levels exceed their short-circuit current can be hazardous to persons and property. SCCRs marked on
components and assemblies makes it easier to verify proper protection for components and assemblies for specific
applications, whether it be the initial installation or relocation of equipment.
NEC ARTICLE 409.110:
An industrial control panel shall be marked with the following information that is plainly visible after installation:
1. Manufacturer’s name, trademark, or other descriptive marking by which the organization responsible for the
product can be identified.
2. Supply voltage, phase, frequency, and full-load current.
3. Short-circuit current rating of the industrial control panel based on one of the following:
a. Short-circuit current rating of a listed and labeled assembly.
b. Short-circuit current rating established utilizing an approved method (FPN: UL508A-2001, Supplement
SB, is an approved method)
4. If the industrial control panel is intended as service equipment, it shall be marked to identify it as being
suitable for use as service equipment.
5. Electrical wiring diagram or the number of the index to the electrical drawings showing the electrical wiring
diagram.
6. An enclosure type number shall be marked on the industrial control panel enclosure.
WHAT IS A SHORT-CIRCUIT CURRENT RATING:
SCCRs on components and assemblies represent the maximum level of short-circuit current that the component or
assembly can withstand and is used for determining compliance with NEC. This rating can be marked on individual
components or assemblies. Assembly ratings take into account all components contained within the equipment.
A common mistake is to assume that the interrupting rating of the overcurrent protective device protecting the
circuit represents the SCCR for the entire circuit. Interrupting ratings, used for compliance with NEC apply solely to
the overcurrent protective device. It is the characteristics of the overcurrent protective device (e.g. opening time,
let-through energy) that need to be used in determining compliance with NEC, not the interrupting rating.
High SCCRs eliminate the need to apply current limiting provisions in feeder circuits and allow for more installations
where equipment can be installed.
WHO IS AFFECTED BY THE SCCR MARKINGS:
The 2005 NEC has requirements for anyone building equipment listed to the 2005 NEC or to UL508A and requires
the following to be marked with an SCCR:
1. Industrial control panels [409.110].
2. Industrial machinery electrical panels [670.3(A)].
3. HVAC equipment [440.4(B)].
4. Meter disconnect switches [230.82(3)].
5. Motor controllers [430.8].
VTAC 9 SHORT-CIRCUIT CURRENT RATINGS:
Rockwell Automation VTAC 9 catalog number assemblies have all undergone short-circuit testing and are listed
under UL508C file E59272 Volume 17 Section 2.
ISC
Voltage
208V AC
480V AC
HP
Drive
Frame
1
2
3
5
7.5
10
15
20
25
30
40
50
60
75
100
1
2
3
5
7.5
10
15
20
25
30
40
50
60
75
100
125
150
200
B
B
B
C
D
D
D
E
E
4
5
5
6
6
6
B
B
B
B
C
C
D
D
D, 2
D, 3
E, 3
E, 3
4
5
5
6
6
6
Drive
Only
(-D00)
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
200 kA
Style A
Main
Input
Disc.
(-A10)
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
-
Style B
Main
Input
Disc. with
Fuse
(-A30)
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
-
Terminal
Block
Main
Input
Disc.
Fuse
Only
(-B00)
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
-
(-B10)
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
-
(-B20)
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
-
Main
Input
Disc. and
Fuse
(-B30)
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
100 kA
-
Style M
Motor
Circuit
Prot.
Main Input
Disc. and
Fuse
(-M40)
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
65 kA
50 kA
65 kA
65 kA
65 kA
-
(-M30)
100 kA
100 kA
100 kA
-
GLOSSERY OF TERMS:
Industrial Control Panel – An assembly of a systematic and standard arrangement of two or more components
such as motor controllers, overload relays, fused disconnect switches and related control devices such as selector
switches with associated wiring and terminal blocks.
Interrupting Rating – The highest current at rated voltage that a protective device is intended to interrupt under
standard test conditions without rupturing or causing additional damage. Fuses and circuit breakers are typically
marked with an Interrupt Rating.
Short-Circuit Current Rating – The prospective symmetrical fault current at nominal voltage to which an
apparatus of system is able to be connected without sustaining damage exceeding the defined acceptance criteria.
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Publication 9VT-TD002A-EN-P – January 2007
Copyright © 2006 Rockwell Automation, Inc.. All rights reserved. Printed in USA.