UL508A Industrial Control Panels Standard

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 Edtition of UL508A. It supersedes the previous verion of this document dated October 21, 2019.

Remote VFD Control Panel

UL, in the form of the UL inspector, will carefully consider many factors while determing 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 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

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

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
	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.
	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
36.4.1 Miscellaneous power devices	Listed Surge Protective Devices	UL 1449	VZCA	120Vac 1-Phase 2W+G Single Phase	DS72US-120S/G
				120-240Vac 1-Phase 2W+G Single Phase	DS72US-240T/NN
				120/240Vac 1-Phase 3W+G Split Phase	DS73US-120T/G
				120/208Vac 3-Phase 4W+G Wye	DS74US-120Y/G
				277/480Vac 3-Phase 4W+G Wye	DS74US-277Y/G
				480Vac 3-Phase 3W+G Delta	DS74US-480D
47.1.1 Surge control devices	Listed Surge Protective Devices	UL 1449	VZCA	120Vac 1-Phase 2W+G Single Phase	DS72US-120S/G
				120-240Vac 1-Phase 2W+G Single Phase	DS72US-240T/NN
				120/240Vac 1-Phase 3W+G Split Phase	DS73US-120T/G
				120/208Vac 3-Phase 4W+G Wye	DS74US-120Y/G
				277/480Vac 3-Phase 4W+G Wye	DS74US-277Y/G
				480Vac 3-Phase 3W+G Delta	DS74US-480D
47.1.3 Surge control devices	Listed isolated Loop Circuit Protectors	UL 479B	QVGQ	RS422	DLA-06D3
				RS232 RS485	DLA-12D3
				4-20mA Current Loop	DLA-24D3
				48Vdc	DLA-48D3
75.8.4 Service Equipment Use	Surge Protective Devices	UL 1449	VZCA	120Vac 1-Phase 2W+G Single Phase	DS72US-120S/G
				120-240Vac 1-Phase 2W+G Single Phase	DS72US-240T/NN
				120/240Vac 1-Phase 3W+G Split Phase	DS73US-120T/G
				120/208Vac 3-Phase 4W+G Wye	DS74US-120Y/G
				277/480Vac 3-Phase 4W+G Wye	DS74US-277Y/G
				480Vac 3-Phase 3W+G Delta	DS74US-480D

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