{"id":4175,"date":"2023-01-05T14:03:34","date_gmt":"2023-01-05T13:03:34","guid":{"rendered":"https:\/\/www.gt-engineering.it\/normative-tecniche\/%tipologia_normativa%\/ul-891-switchboards\/"},"modified":"2025-08-19T08:35:29","modified_gmt":"2025-08-19T07:35:29","slug":"ul-891-switchboards","status":"publish","type":"normativa_tecnica","link":"https:\/\/www.gt-engineering.it\/en\/technical-standards\/ul-and-nfpa-standards\/ul-891-switchboards\/","title":{"rendered":"UL 891: Switchboards, Tristandard"},"content":{"rendered":"\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n        \n                    <div\n                class=\"h-auto mb-6 md:mb-4 lg:mb-8 xl:mb-9 float-left mr-6 md:mr-4 lg:mr-8 xl:mr-9  overflow-hidden shadow-content-image w-full md:w-1\/3\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Inside-150x150.jpg.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"272\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Inside-300x272.jpg.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"697\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Inside-768x697.jpg.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"929\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Inside-1024x929.jpg.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Inside.jpg.webp\"\r\n                                                        title=\"Inside\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p style=\"text-align: justify;\">UL 891 is a Tristandard. That means it is exactly the same content in the following three norms:<\/p>\n<ul>\n<li style=\"text-align: justify;\">CSA Group: CSA C22.2 No. 244-05.<\/li>\n<li style=\"text-align: justify;\">Underwriters Laboratories Inc: UL 891.<\/li>\n<li style=\"text-align: justify;\">Association of Standardization and Certification: NMX-J-118\/2-ANCE-2012.<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">The subjects are the SWITCHBOARDS, also called in North America &#8220;dead-front switchboard&#8221;. In Europe the equivalent standards are the EN 61439-1 and EN 61439-2. However the approach is different. EN 61439 puts a lot of emphasis on the Design Verification and cabinet testing. UL 891 is mainly about how to design the switchboard.<\/p>\n<p style=\"text-align: justify;\">The Standard applies to switchboards nominally rated at 600 V or less and intended for use in accordance with the Canadian Electrical Code, Part 1 (CE Code, Part 1), the National Electrical Code (NEC), ANSI\/NFPA 70, and the Mexican Standard for Electrical Installations (Utility), NOM-001-SEDE.<br \/>\nThese requirements cover switchboards for use on circuits having available RMS symmetrical short-circuit currents of not more than 200 000 A.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:block\">\n\n    \n                    <div class=\"mb-6 relative w-full md:mb-4 lg:mb-8 xl:mb-9\">\n                \n        <div                class=\"m-headings\"\n            >\n    \n    \n<h4 class=\"a-heading text-primary font-heading text-2xl lg:text-3xl xl:text-4xl normal mt-2 first:mt-0\">\n                    Table G3.1    <\/h4>\n        <\/div>\n                <\/div>\n        \n        \n                    <div class=\"relative w-full\">\n                \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p style=\"text-align: justify;\">It is one of the most important tables to comply with. It details the minimum distance between bus bars, depending upon the Switchboard declared Shortcircuit current, the Ampere and Voltage Rating.<br \/>The bus bars can be arranged in a edge to edge (EE) or face to face (FF) layout. That is important because it changes the minimum distance between them.<\/p>\n<p style=\"text-align: justify;\">&nbsp;<\/p>\n<\/div>            <\/div>\n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n\n\n\n\n    \n        <section\n            data-name=\"Contenuto testuale con immagine\"\n            class=\"bow-gte-testo-media u-spacer-base\"\n            id=\"\"\n        >\n            \n<div class=\"o-text-media px-side-spacer sm:px-side-spacer-sm lg:px-side-spacer-tablet 2xl:px-side-spacer-desktop flex flex-wrap items-start md:flex-row\">\n\n    \n\n                    <div \n                class=\"order-2 relative w-full md:w-1\/2\"\n            >\n                <div\n                    class=\"pt-6 space-y-6 w-full md:pt-0 md:space-y-4 lg:space-y-8 xl:space-y-9  md:pl-12 xl:pl-24\"\n                >\n                    \n<div class=\"a-text font-text text-base normal mt-8 first:mt-0 space-y-4\">\n    <p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<\/div>                <\/div>\n            <\/div>\n        \n                    <div\n                class=\"h-auto order-1 mb-8 md:mb-0   overflow-hidden shadow-content-image w-full md:w-2\/3\"\n            >\n                \r\n\r\n    \r\n        \r\n            \r\n                \r\n                    <picture\r\n                        class=\"\"\r\n                                            >\r\n                                                                                                        <source\r\n                                media=\"(max-width: 150px)\"\r\n                                width=\"150\"\r\n                                height=\"150\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Immagine1-13-150x150.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 300px)\"\r\n                                width=\"300\"\r\n                                height=\"208\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Immagine1-13-300x208.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 768px)\"\r\n                                width=\"768\"\r\n                                height=\"533\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Immagine1-13-768x533.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                                <source\r\n                                media=\"(max-width: 1024px)\"\r\n                                width=\"1024\"\r\n                                height=\"711\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Immagine1-13-1024x711.png.webp\"\r\n                                type=\"image\/webp\"\r\n                            \/>\r\n                                                                            <img\r\n                            class=\"a-image transparent border-image h-auto  w-full mx-auto\"\r\n                                                        srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/Immagine1-13.png.webp\"\r\n                                                        title=\"Immagine1\"\r\n                                                        type=\"image\/webp\"\r\n                        \/>\r\n                    <\/picture>\r\n\r\n                \r\n\r\n                    \r\n    \r\n            <\/div>\n        \n    <\/div>\n        <\/section>\n\n    \n","protected":false},"excerpt":{"rendered":"<p>UL 891 is a Tristandard. That means it is exactly the same content in the following three norms:<\/p>\n<p>\tCSA Group: CSA C22.2 No. 244-05.<br \/>\n\tUnderwriters Laboratories &#8230;<\/p>\n","protected":false},"author":1,"featured_media":50074,"parent":0,"menu_order":12,"template":"","meta":{"_acf_changed":false,"footnotes":""},"normative-tecniche":[59],"class_list":["post-4175","normativa_tecnica","type-normativa_tecnica","status-publish","has-post-thumbnail","hentry","tipologia_normativa-ul-and-nfpa-standards"],"acf":{"sottotitolo":"The Tristandard of the North America","allegati":null},"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.2 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>UL 891: Switchboards | North America Tristandard<\/title>\n<meta name=\"description\" content=\"UL 891 is a Tristandard. That means it is exactly the same content in the following three norms: CSA Group: CSA C22.2 No. 244-05. 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