{"id":49493,"date":"2025-08-18T11:36:23","date_gmt":"2025-08-18T10:36:23","guid":{"rendered":"https:\/\/www.gt-engineering.it\/?post_type=normativa_tecnica&p=49493"},"modified":"2025-08-18T16:03:52","modified_gmt":"2025-08-18T15:03:52","slug":"ul-508a-july-2022-update","status":"publish","type":"normativa_tecnica","link":"https:\/\/www.gt-engineering.it\/en\/technical-standards\/ul-and-nfpa-standards\/ul-508a\/ul-508a-july-2022-update\/","title":{"rendered":"UL 508A \u2013 July 2022 update"},"content":{"rendered":"\n\n \n \n \n
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A new update of the standard was officially published in july 2022.<\/u><\/strong> Hereafter we give you some insights of the main changes.<\/p>\n<\/div> <\/div>\n \n \n

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\n FULL LOAD AMPERAGE vs. FULL LOAD CURRENT <\/h2>\n <\/div>\n <\/div>\n \n \n
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In the past, as GT Engineering, we have consistently discussed the inaccuracy of the terms\u00a0\u00a0<\/span>FLA and FLC<\/span><\/strong>\u00a0\u00a0in the UL 508A standard. Therefore, in 2021, we submitted a request to align the use of these two terms with the NEC. Here are some thoughts on the changes.<\/span><\/p>\n

“UL 508A, in Clause 52.1 (which cross-references Clause 49.1), requires that the panel plate state the ”\u00a0<\/span>full-load amperage rating<\/span><\/strong>\u00a0.” NFPA 79 refers to “full-load current” (Article 16.4). The NEC (NFPA 70) requires, in Article 670.3(A)(1), that the nameplate list information, including the “full-load current” of the switchgear.<\/span><\/p>\n

The use of “Full-load ampere rating” in UL 508A should be replaced with\u00a0\u00a0<\/span>“Full-load current<\/span><\/strong>\u00a0,” where the meaning is the same as in NFPA 79 or the NEC. Specifically, Section 29.6.1 of UL 508A names the currents in Table 50.1 “Full-load ampere rating.” The table is equivalent to the table in NEC 430.250, and the name used is “Full-load current.” The title of Table 50.1 is “Full-load motor-running currents in amperes corresponding to various ac horsepower ratings,” while the equivalent table in the NEC is Table 430.250, “Full-Load Current, Three-Phase Alternating-Current Motors.” We proposed to change the title of Table 50.1 to “Full-Load currents in amperes corresponding to various ac horsepower ratings.”<\/span><\/p>\n

This proposal was welcomed and will be implemented in the new edition of the standard. Perhaps the most important aspect is that the nameplate, referring to the entire control panel, will no longer display “Total FLA” but the more correct term “Full-load current (FLC).”<\/span><\/p>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n\n\n\n\n \n \n \n
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\n TERMINATION TEMPERATURE <\/h2>\n <\/div>\n <\/div>\n \n \n
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Another change in the 2022 version of UL 508A relates to how to\u00a0<\/span>\u00a0choose between the 60\u00b0C and 75\u00b0C columns in Table 28.1.<\/span><\/strong>
\nOne important aspect of\u00a0<\/span>reducing the risk of fire is that the cable’s ampacity must also be determined based on the maximum temperature that the terminals of a circuit breaker<\/span><\/strong>\u00a0, for example, can reach. This is clearly stated in the NEC in Article 110.14(C).<\/span><\/p>\n

[NEC: 2020] 110.14 (C) Temperature Limitations.<\/span>
\nThe temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any termination, conductor, or connected device. [\u2026]<\/span><\/p><\/blockquote>\n

The problem is that not all components specify the maximum temperature of their terminations. Normally, it can be 60\u00b0C or 75\u00b0C. Therefore, clarification is needed to determine the ampacity of internal conductors, as it is unclear how to use Table 28.1 regarding the different ampacities based on the conductor insulation temperature (\u00a0<\/span>60\u00b0C column vs. 75\u00b0C column)<\/span><\/strong>\u00a0. This revision also aligns with the requirements of NEC Section 110.14(C)(1). While this section addresses field wiring terminations,\u00a0\u00a0<\/span>it establishes the minimum requirements for conductor temperature ratings inside an industrial control panel<\/span><\/strong>\u00a0\u00a0used in circuits of 100 amperes or less and circuits of more than 100 amperes.<\/span><\/p>\n

[UL 508A:2022]<\/span><\/strong>\u00a0\u00a029.6 Sizing<\/span>
\n[\u2026]<\/span>
\nThe wire temperature rating shown on the component or in the instructions shall be used to select the appropriate column(s) of Table 28.1 as follows:<\/span>
\n1) [\u2026]<\/span>
\n4) If the wire temperature rating is not shown on the component or in the instructions, the conductor size shall be determined using the amperages in the 60\u00b0C column of Table 28.1 when the component has a current rating of 100 amperes or less, and in the 75\u00b0C column of Table 28.1 when the component has a current rating of more than 100 amperes.<\/span><\/p><\/blockquote>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n\n\n\n\n \n \n \n
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\n ROOM TEMPERATURE <\/h2>\n <\/div>\n <\/div>\n \n \n
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It is finally possible to certify industrial control panels installed at ambient temperatures above 40\u00b0C. This was already permitted in Canada and is now also permitted in the United States. The new wording can be found in\u00a0<\/span>\u00a0section 1.1<\/span><\/strong>\u00a0\u00a0of the UL 508A 2022 standard.<\/span><\/p>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n\n\n\n\n \n \n \n
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\n CLASS A CIRCUIT BREAKER REQUIRED ON SOCKETS <\/h2>\n <\/div>\n <\/div>\n \n \n
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With the 2022 update to UL 508A, the standard is now fully aligned with NFPA 79 (and IEC 60204-1) regarding the requirement for a Class A ground fault circuit interrupter (GFCI) on all general purpose receptacle outlets. The new wording is found in Section\u00a0\u00a0<\/span>66.4.4.<\/span><\/strong><\/p>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n\n\n\n\n \n \n \n
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\n ACCESS TO THE BOARD <\/h2>\n <\/div>\n <\/div>\n \n \n
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The 2022 update aligned the enclosure access requirements with NFPA 79. Generally, door interlocks are no longer required. It is no longer necessary to lock all doors when power is present inside the enclosure. It is no longer necessary to open the main panel disconnect to open the doors. We now have a similar international approach to the risk of direct contact inside an automation panel, as IEC 60204-1, NFPA 79, UL 508A, C22.2 No. 301, and C22.2 No. 286 have been somewhat standardized in this regard.<\/p>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n\n\n\n\n \n \n \n
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\n CONSIDERATIONS <\/h2>\n <\/div>\n <\/div>\n \n \n
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The UL 508A<\/span><\/strong>\u00a0standard\u00a0\u00a0\u00a0only concerns automation panels (industrial control panels), in which there are, for example, programmable logic controllers, contactors, drives; while for distribution panels (distribution boards), in which busbar systems are usually located, reference should be made to the UL 891 standard. It should be noted that the UL 508A standard now contains requirements for the dimensioning of distribution panels inside which busbar systems are located.<\/span><\/p>\n

To be used in an \u201cindustrial control panel,\u201d any component must be certified (\u201clisted\u201d or \u201crecognized\u201d).<\/span><\/p>\n

However, this is not enough to make the panel compliant with UL 508A. The sizing of motor starters and the main switch follows different rules than those of EN 60204-1. The main problems that can be encountered with the approval of control panels in the United States are:<\/span><\/p>\n

Certified switches that are used incorrectly. In addition to sizing, great care must be taken when using switches that, according to their certification (UL1077, UL489, etc.), must have very specific applications within the switchboard.<\/span>
\nNon-compliance with electrical distances between cables, devices, etc.<\/span>
\nAbsence of a switchboard nameplate or incomplete information on the switchboard’s characteristics.<\/span>
\nTransformers not certified according to the corresponding technical standard or certified only for conductor insulation.<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n<\/div> <\/div>\n \n \n

<\/div>\n \n\n <\/div>\n <\/section>\n\n \n","protected":false},"excerpt":{"rendered":"

A new update of the standard was officially published on 26 June 2025.\u00a0Being members of the UL 508A Committee, hereafter we give you some insights of the main changes.<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":4095,"menu_order":0,"template":"","meta":{"_acf_changed":false,"footnotes":""},"normative-tecniche":[59],"class_list":["post-49493","normativa_tecnica","type-normativa_tecnica","status-publish","hentry","tipologia_normativa-ul-and-nfpa-standards"],"acf":{"sottotitolo":"","allegati":null},"yoast_head":"\nUL 508A \u2013 July 2022 update - Gt-Engineering<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.gt-engineering.it\/en\/technical-standards\/ul-and-nfpa-standards\/ul-508a\/ul-508a-july-2022-update\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"UL 508A \u2013 July 2022 update - 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