UL 231, Power Outlets

Effective March 13, 2018

Standard Information
Standard Number:
UL 231
Standard Name:
Power Outlets
Standard Edition and Issue Date:
10th Edition Dated October 5, 2016
Date of Previous Revisions to Standard:
9th Edition Revised September 11, 2014
Effective Date of New/Revised Requirements

Effective Date: March 13, 2018

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 will 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requests in writing that current requirements be used along with their understanding that their listings will be withdrawn on Effective Date noted above, unless the product is found to comply with new/revised requirements.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:

  • Additional comprehensive review of component access in revised 8.2.8
  • Type WR receptacles added to 8.2.11
  • Loop feed current rating added in 32.3 and 10.1.9
  • ”Extra-duty” outlet box hoods added in revised 5.7.2

Specific details of new/revised requirements are found in table below.

If the applicable requirements noted in the table are not described in your report(s), these requirements will need to be confirmed as met and added to your report(s) such as markings, instructions, test results, etc. (as required).

Client Action Required:

Information – 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 – Please immediately identify any current Listing Reports or products that are no longer active and should be removed from our records.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
5.7.2 Additions to existing requirements are underlined below.

A door or cover over an opening in the enclosure as well as a door or cover provided to keep rain from a receptacle or a switch and circuit breaker handle shall comply with the requirements for doors and covers. Outlet box hoods installed for this purpose shall comply with requirements for “Extra-Duty” outlet box hoods in the Standard for Cover Plates for Flush-Mounted Wiring Devices, UL 514D.
8.2.8 Additions to existing requirements are underlined and deletions are shown lined out below.

A receptacle other than the duplex type that is mounted with its face in a vertical plane shall be positioned so that the grounding contact is at the top and the area below the receptacle shall be free of any other component (switch or circuitbreaker handle, receptacle, or the like), the access to which would be blocked by the flexible cord attached to a right-angle attachment plug.

A receptacle shall be positioned so that when the mating attachment plug, including a right-angled attachment plug for non-locking configurations, is inserted, neither the attachment plug nor the flexible cord blocks access to any component such as a switch, circuit-breaker handle, other receptacles or the like. For the purpose of this requirement, access shall be considered blocked if the location of the attachment plug or cord requires the user to reach behind the plug or cord to access the component, or obscures the “on-off” markings of the component to a point where they are not clearly identifiable. Exception: This requirement does not apply to controls and indicators that are an integral part of the receptacle, such as the test and reset button on a duplex type receptacle with integral GFCI protection.
8.2.11 New clause added;

All 15- and 20-ampere, 125- and 250-volt nonlocking receptacles, including receptacles with integral Class A ground-fault circuit protection for personnel, shall be rated as “weather-resistant” type in accordance with the Standard for Attachment Plugs and Receptacles, UL 498.
10.1.9 Additions to existing requirements are underlined and deletions are shown lined out below.

A bus for through-connection shall be determined to be at least equivalent in ampacity to the connector or connectors serving the bus.

A power outlet marked with a loop feed current rating, as specified in 32.3, shall be provided with a means to interconnect the loop feed conductors and the tap conductors that connect to the power outlet. The ampacity of the connection means of the loop feed conductor shall be suitable for the loop feed current rating, and the ampacity of the tap conductor shall be suitable for the power outlet being connected.
32.3 New clause added;

A power outlet with wire connecting devices for loop feed installation shall be provided with a “Loop Feed Current Rating” that is not more than the ampacity of the connectors to which the loop feed conductors are spliced.

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.