{"id":4159,"date":"2023-01-05T14:16:27","date_gmt":"2023-01-05T13:16:27","guid":{"rendered":"https:\/\/www.gt-engineering.it\/normative-tecniche\/%tipologia_normativa%\/ul-508a-definizioni\/"},"modified":"2025-08-18T15:37:56","modified_gmt":"2025-08-18T14:37:56","slug":"ul-508a-definitions","status":"publish","type":"normativa_tecnica","link":"https:\/\/www.gt-engineering.it\/en\/technical-standards\/ul-and-nfpa-standards\/ul-508a\/ul-508a-definitions\/","title":{"rendered":"UL 508A &#8211; Definitions"},"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\/2\"\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\/branch_feeder-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=\"260\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/branch_feeder-300x260.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=\"665\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/branch_feeder-768x665.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=\"886\"\r\n                                srcset=\"https:\/\/www.gt-engineering.it\/wp-content\/uploads\/2023\/01\/branch_feeder-1024x886.png.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\/branch_feeder.png.webp\"\r\n                                                        title=\"branch_feeder\"\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><strong>Branch circuit<\/strong>:it is the utility circuit; it is the part of the circuit that starts from the load (e.g. motor) and ends at the first short circuit protection (Branch Circuit Protection&nbsp;Device or BCPD).<\/p>\n<p><strong>Feeder circuit<\/strong>: indicates the supply circuit, i.e. all the elements upstream of the BCPD.<\/p>\n<p><strong>Power circuit<\/strong>: the power circuit (e.g. motor starter); it can be connected directly to the supply circuit or supplied by a power transformer.<\/p>\n<p><strong>Control circuit<\/strong>: it is the circuit that transmits the control signals for the machines or the system. Control circuits are generally limited to 15 A.<\/p>\n<p>Power circuits and Control circuits require the appropriate protection devices (UL 508, UL 489 or UL 1077).<\/p>\n<p>An example of&nbsp;Branch Circuit and Feeder Circuit taken from the Standard is shown in the figure here next.<\/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        \n        \n        \n        \n                <div class=\"clear-both\"><\/div>\n        \n\n    <\/div>\n        <\/section>\n\n    \n","protected":false},"excerpt":{"rendered":"<p>Some general definitions, usefull for a deeper understanding of the topic<\/p>\n","protected":false},"author":1,"featured_media":4160,"parent":4095,"menu_order":7,"template":"","meta":{"_acf_changed":false,"footnotes":""},"normative-tecniche":[59],"class_list":["post-4159","normativa_tecnica","type-normativa_tecnica","status-publish","has-post-thumbnail","hentry","tipologia_normativa-ul-and-nfpa-standards"],"acf":{"sottotitolo":"What are Branch circuits, Feeder circuits, Power circuits and Control circuits?","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 508A - Definitions<\/title>\n<meta name=\"description\" content=\"What are Branch circuits, Feeder circuits, Power circuits and Control circuits? 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