Effective December 20, 2014

Addendum Added instructions to the Client Action Required and Information sections not identified in the original SUN Issued May 15, 2014.

Standard Information
Standard Number:
UL 508A
Standard Name:
Industrial Control Panels
Standard Edition and Issue Date:
2nd Edition Dated December 20, 2013
Date of Revisions:
January 13, 2014
Date of Previous Revisions to Standard:
1st Edition Revised February 4, 2010
Effective Date of New/Revised Requirements

Effective Date (see Schedule below): December 20, 2014

Impact, Overview, Fees and Action Required

Impact Statement:  A review of all Listing Reports is necessary to determine which products comply with new/revised requirements and which products might require re-evaluation.  NOTE:  Effective immediately, this revised standard will be exclusively used for evaluation of new products unless the Applicant requests in writing that current requirements be used along with their understanding that their listings will be withdrawn on Effective Date noted above, unless the product is found to comply with new/revised requirements.

Overview of Changes:  This is a new 2nd Edition of UL 508A.  These new/revised requirements are in accordance with SDO Proposals dated December 2, 2011 and January 11, 2013 and are extensive.  As such a modified and updated General Coverage Certification Report has been prepared and will be used to upgrade all current ETL Listed UL 508A Reports.  Specific details of new/revised requirements are found in table below.  It is intended that Intertek Field Representatives will confirm compliance of panel constructions and typically no sample will be necessary for review/examination at an Intertek facility.

Schedule:  So that shipping of products with Listing Marks will not be interrupted, an approximate schedule has been established to ensure Listing Reports are found compliant by Effective Date:

  • May 23, 2014 = 7 Month Report Review – Intertek begins review and update all Reports.
  • December 20, 2014 = Effective Date – All UL 508A General Coverage Reports and other non-general coverage reports are updated to show compliance with the new 2nd Edition of UL 508A.

Fees:  All Intertek UL 508A General Coverage certification reports will need to be updated to a new “CDR” format which includes all new/revised requirements of this SUN.  Update of certification reports is expected to take no more than 1 day and will be covered by a direct billing project to be invoiced at no more than $1200 per report.

Client Action Required:

As part of the process of upgrading to the 2nd edition of UL 508A, a new, simpler, Listing Report has been prepared and will be replacing the previous, lengthy, listing report.  As part of this process, it will be necessary for the customer to have on-site a current edition of the certification standard (2nd Edition of UL 508A).  To obtain a copy of the standard, please visit our corporate page at www.intertek.com/standards-updates and click on “Buy Standards”, this link will route you to the TechStreet store. 
Part of this change is to align with other Certification Bodies offering UL 508A certifications in NA.  A current standard will need to be on site effective 2015 Quarter 1 inspections.


As the changes to the Standard and process are extensive, we recommend that your technical representative(s) in charge of verifying compliance with the standard attend a UL 508A training session prior to the effective date.  Intertek will be offering training sessions in various locations or arrangements can be made to present the training material at your site.  Please contact your account representative for details.

To assist our Engineer with review of your Listing Reports, please submit technical information in response to the new/revised paragraphs noted in the attached or explain why these new/revised requirements do not apply to your product (s).

Current Listings Not Active? – Please immediately identify any current Listing Reports or products that are no longer active and should be removed from our records. We will do this at no charge as long as Intertek is notified in writing prior to the review of your reports.

Description of New/Revised Technical Requirements

NOTE: Additions to existing requirements are underlined and deletions are shown lined out below.


From UL’s December 2, 2011 Proposal Bulletin

26.3 New – Air conditioners installed in panels needs to comply with UL 1995 and this clause.
31.3.2 Revised – Adds fuse or breaker rating shall be based on full-load output current rating if a UL 508C compliant variable-speed drive controller is used.
40.1.5 New – When protectors (fuse, breaker, etc.) are in a DC circuit above 32 volts, they must be evaluated to appropriate product standard and have a rating equal to or greater than the operating circuit voltage.
62.4 New – Type 4 or 4X enclosure/compartment that is ventilated must now also comply with 62.4 (including dust test, rod entry test and with any fan on and off.)
93-96 New – Requirements for control panels intended to control permanently installed fountains or floating fountain.
93 – General
94 – Construction
95 – Ratings 
96 - Markings
  From UL’s January 11, 2013 Proposal Bulletin
28.3, 30.2, 31.9, 33.2, 36.1 and 55 New – Requirements added to address power factor correction circuits/capacitors that do not need to be specifically described. 
28.3 – Sizing of terminals
30.2 – Sizing of disconnect switch
31.9 – Sizing of branch circuit protection
33.2 – Sizing/rating of load controllers
36.1 – Capacitors
55 – Cautionary markings
33.7 New – Requirements added to address components provided that are configured as autotransformers- and resistor-type reduced voltage motor controllers
97-99 New – Requirements for control panels intended to control irrigation equipment.
97 – General
98 – Construction
99 - Marking

CUSTOMERS PLEASE NOTE: This Table and column "Verdict" can be used in determining how your current or future production is or will be in compliance with new/revised requirements.

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