UL508A Industrial Control Panels Standard
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| UL508A Industrial Control Panel |
Overview
In North America, UL approval provides independent 3rd Party certification that a product has been tested by Underwriters Laboratories (UL) or another Nationally Recognized Testing Laboratory (NRTL) and meets all necessary electric code safety requirements as well as industry benchmarks.
On April 13, 2020, UL released a UL508A supplement document titled "REQUIREMENTS FOR COMPONENTS USED IN INDUSTRIAL CONTROL PANELS" that was published with the intent to help control panel builders determine the requirements for components when used in industrial control panels. The document replaces what was Supplement SA in the Second Edition of UL508A, and subsequently Appendix C in the Third Edition of UL508A. It supersedes the previous version of this document dated October 21, 2019.
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| Remote VFD Control Panel |
UL, in the form of the UL inspector, will carefully consider many factors while determining the fitness of the Surge Protective Device (SPD) for the equipment that is being evaluated for UL compliance. It is critically important to understand the process that UL will use to evaluate the SPD according to UL508A.
Each component belongs to an individual Category that describes the specific requirements of the component. In a UL508A Industrial Control Panel, the Surge Protective Device will be evaluated based on Sections 36, 47, and 75. These sections are referenced in Table 1 of the Supplement document.
Table 1 - Components that comply with specific requirements
| UL508A Section/Paragraph Reference |
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| Section 36 - Miscellaneous power devices meeting component selection requirements |
| UL508A Paragraph reference | Component description | UL Standard | Category control number(s) | Notes |
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| 36.4.1 | Recognized Surge Protective Devices | UL 1449 | VZCA2 | SPDs that are outside the guidelines of Table 2 must be procedure described |
| 36.4.1 | Listed Surge Protective Devices | UL 1449 | VZCA | Type 1, 2 or 3 SPDs that are outside the guidelines of Table 2 must be procedure described |
| Section 47 - Surge control devices meeting component selection requirements |
| UL508A Paragraph reference | Component description | UL Standard | Category control number(s) | Notes |
|---|---|---|---|---|
| 47.1.1 | Recognized Surge Protective Devices | UL 1449 | VZCA2 | SPDs that are outside the guidelines of Table 2 must be procedure described |
| 47.1.1 | Listed Surge Protective Devices | UL 1449 | VZCA | Type 1, 2 or 3 SPDs that are outside the guidelines of Table 2 must be procedure described |
| 47.1.3 | Listed isolated Loop Circuit Protectors | UL 497B | QVGQ | - |
| 47.1.3 | Recognized isolated Loop Circuit Protectors | UL 497B | QVGQ2 | Procedure described |
| Section 75 - Service Equipment Use - components meeting specific selection requirements |
| UL508A Paragraph reference | Component description | UL Standard | Category control number(s) | Notes |
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| 75.8.4 | Surge Protective Devices | UL 1449 | VZCA | Type 1 SPD Only |
The first step in determining the acceptability of the SPD for a given application or piece of equipment is to consider the UL SPD Type. This is the case for UL 508A as well as all other UL Listed equipment. This first level compliance is based on the UL Approval (LISTED
or RECOGNIZED
) of the SPD or UL SPD Type and it’s Suitable Ratings. This means that the SPD has met all safety, performance, environmental and electrical system ratings of the application.
If any of these criteria are not fully met, it will require a Procedure Description, a File Update and/or Additional Testing. These actions will require additional costs that may be substantial. For this reason, it is in the interest of the specifier to use UL LISTED
SPD (Type 1 or Type 2) to eliminate any uncertainty or to make sure the UL RECOGNIZED
SPD (Type 1CA, Type 2CA, Type 4CA, Type 5) is selected at the initial UL evaluation of the control panel or at the submittal of the equipment to UL for compliance testing.
Table 2 - Use of Surge Protective Devices
| Type of Surge Protective Device (SPD) - One port only* |
| Listed Type 1 | Listed Type 2 | Listed Type 3 | R/C Type 4 Component Assembly | R/C Type 5 | ||
| Location of the SPD | ||||||
| Service Equipment Supply Side of Overcurrent Protection | w | z | z | z | z | |
| Service Equipment Load Side of Overcurrent Protection | w | w | z | z | z | |
| Non-Service Equipment Feeder or Branch Circuits | w | w | w | z | z | |
| Isolated Control Circuits | w | w | w | w | w | |
| Ratings | ||||||
| Service Equipment Supply Side of Overcurrent Protection | Vb | x | z | z | z | z |
| In c | y | z | z | z | z | |
| Service Equipment Load Side of Overcurrent Protection | Vb | x | x | z | z | z |
| In c | y | 10kA | z | z | z | |
| Non-Service Equipment Feeder or Branch Circuits | Vb | x | x | x | z | z |
| In c | y | y | y | z | z | |
| Isolated Control Circuits | Vb | x | x | x | x | x |
| In c | y | y | y | 3kA | 3kA |
| NOTES | |
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| (1) | A "w" indicates an allowable location for the SPD. |
| (2) | An "x" indicates a Normal Operating Voltage Rating is required as specified in footnote "b" below. |
| (3) | A "y" indicates a Nominal Discharge Current Rating as specified in footnote "c" below is not required. |
| (4) | A "z" indicates the SPD needs further evaluation to determine suitability and Procedure description is required. |
| (a) | A Two-Port SPD shall be Listed and comply with the ratings specified above for the intended application. In addition, it shall have an appropriate short circuit current rating (SCCR) rating. |
| (b) | V - Normal Operating Voltage Rating - Operating Voltage and MCOV ratings shall be equal to or greater than the applied circuit Line-to-Line (full phase) voltage. |
| (c) | In (NDC) - Nominal Discharge Current - Amount of peak current "forced" through the device during Surge Testing. |
To help control panel builders select the right SPD based on the UL508A Industrial Control Panels standard, CITEL
, in consultation with Underwriters Laboratories (UL), has made this quick reference table. If you have any questions on how to use this table or any technical and compliance questions, please contact CITEL.
Approval Considerations based on UL SPD Type
| UL Mark | UL1449 SPD Type | Suitable Ratings | Procedure Described | File Update or Additional Testing | Notes |
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| 1 2 | Yes | No | No | The only requirement is that the SPD must match electrical and environmental ratings of the UL 508A Control Panel. A UL field inspection of the control panel with the SPD installed is required as a part of a standard follow-up service visit. |
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| 1CA 2CA 4CA 5 | Yes | Yes | Yes | Yes – All UL recognized SPD’s require a UL engineering evaluation of the SPD’s existing UL1449 E–file. This will result, at a minimum, in a cost to update the UL file and may also require testing that would result in additional costs. |
CITEL
UL LISTED
SPD meeting all requirements of UL508A
The following is a list of products for each section. They are UL Listed SPD and require only that they meet the "Suitable Rating" of the control panel. They can be used in all UL locations including,
- Service Equipment Supply Side of Overcurrent Protection
- Service Equipment Load Side of Overcurrent Protection
- Non-Service Equipment Feeder or Branch Circuits
- Isolated Control Circuits
| UL508A Paragraph reference | Component description | UL Standard | Category control number(s) | System | Part # | Link |
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| 36.4.1 Miscellaneous power devices | Listed Surge Protective Devices | UL 1449 | VZCA | 120Vac 1-Phase 2W+G Single Phase | DS72US-120S/G |
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| 120-240Vac 1-Phase 2W+G Single Phase | DS72US-240T/NN |
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| 120/240Vac 1-Phase 3W+G Split Phase | DS73US-120T/G |
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| 120/208Vac 3-Phase 4W+G Wye | DS74US-120Y/G |
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| 277/480Vac 3-Phase 4W+G Wye | DS74US-277Y/G |
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| 480Vac 3-Phase 3W+G Delta | DS74US-480D |
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| 47.1.1 Surge control devices | Listed Surge Protective Devices | UL 1449 | VZCA | 120Vac 1-Phase 2W+G Single Phase | DS72US-120S/G |
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| 120-240Vac 1-Phase 2W+G Single Phase | DS72US-240T/NN |
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| 120/240Vac 1-Phase 3W+G Split Phase | DS73US-120T/G |
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| 120/208Vac 3-Phase 4W+G Wye | DS74US-120Y/G |
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| 277/480Vac 3-Phase 4W+G Wye | DS74US-277Y/G |
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| 480Vac 3-Phase 3W+G Delta | DS74US-480D |
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| 47.1.3 Surge control devices | Listed isolated Loop Circuit Protectors | UL 497B | QVGQ | RS422 | DLA-06D3 |
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| RS232 RS485 | DLA-12D3 |
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| 4-20mA Current Loop | DLA-24D3 |
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| 48Vdc | DLA-48D3 |
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| 75.8.4 Service Equipment Use | Surge Protective Devices | UL 1449 | VZCA | 120Vac 1-Phase 2W+G Single Phase | DS72US-120S/G |
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| 120-240Vac 1-Phase 2W+G Single Phase | DS72US-240T/NN |
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| 120/240Vac 1-Phase 3W+G Split Phase | DS73US-120T/G |
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| 120/208Vac 3-Phase 4W+G Wye | DS74US-120Y/G |
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| 277/480Vac 3-Phase 4W+G Wye | DS74US-277Y/G |
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| 480Vac 3-Phase 3W+G Delta | DS74US-480D |
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| 10108 USA Today Way Miramar, FL 33025 USA | Contact us to develop a surge mitigation solution for your application |
| www.citel.us | Where to purchase Citel SPDs |
