{"id":123,"date":"2021-03-23T20:16:22","date_gmt":"2021-03-24T00:16:22","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/chapter\/single-pole-switching\/"},"modified":"2021-04-21T14:49:08","modified_gmt":"2021-04-21T18:49:08","slug":"single-pole-switching","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/chapter\/single-pole-switching\/","title":{"raw":"Single-pole switching","rendered":"Single-pole switching"},"content":{"raw":"The most basic form of lighting control is the <strong>SPST<\/strong> (single-pole, single-throw) switch. Since an electrical load requires two conductors to operate, we can connect a switch in series with a single wire and use it to turn the load on or off.\r\n\r\n[caption id=\"attachment_120\" align=\"aligncenter\" width=\"624\"]<img class=\"wp-image-119 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-schematic-circuit.png\" alt=\"\" width=\"624\" height=\"210\" \/> Schematic diagram of an SPST switch circuit[\/caption]\r\n\r\nLighting loads are commonly energized at 120V, and so utilize a single <strong>ungrounded<\/strong><strong> conductor<\/strong>, and a <strong>grounded conductor<\/strong> as the return path for the current.\r\n\r\nIt is important that we connect our switch in series with the ungrounded conductor so that if the switch is off, and a person were to service a lamp, everything is at ground potential. If the switch were installed in the grounded conductor, then it would still control the lamp, but in the off position, the lamp's components would still be energized to 120 volts, introducing a hazard to anyone servicing the lamp.\r\n\r\n[caption id=\"attachment_120\" align=\"aligncenter\" width=\"640\"]<img class=\"wp-image-120 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-wiring-diagram.png\" alt=\"\" width=\"640\" height=\"360\" \/> Wiring diagram of an SPST switch circuit[\/caption]","rendered":"<p>The most basic form of lighting control is the <strong>SPST<\/strong> (single-pole, single-throw) switch. Since an electrical load requires two conductors to operate, we can connect a switch in series with a single wire and use it to turn the load on or off.<\/p>\n<figure id=\"attachment_120\" aria-describedby=\"caption-attachment-120\" style=\"width: 624px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-119 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-schematic-circuit.png\" alt=\"\" width=\"624\" height=\"210\" srcset=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-schematic-circuit.png 624w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-schematic-circuit-300x101.png 300w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-schematic-circuit-65x22.png 65w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-schematic-circuit-225x76.png 225w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-schematic-circuit-350x118.png 350w\" sizes=\"auto, (max-width: 624px) 100vw, 624px\" \/><figcaption id=\"caption-attachment-120\" class=\"wp-caption-text\">Schematic diagram of an SPST switch circuit<\/figcaption><\/figure>\n<p>Lighting loads are commonly energized at 120V, and so utilize a single <strong>ungrounded<\/strong><strong> conductor<\/strong>, and a <strong>grounded conductor<\/strong> as the return path for the current.<\/p>\n<p>It is important that we connect our switch in series with the ungrounded conductor so that if the switch is off, and a person were to service a lamp, everything is at ground potential. If the switch were installed in the grounded conductor, then it would still control the lamp, but in the off position, the lamp&#8217;s components would still be energized to 120 volts, introducing a hazard to anyone servicing the lamp.<\/p>\n<figure id=\"attachment_120\" aria-describedby=\"caption-attachment-120\" style=\"width: 640px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-120 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-wiring-diagram.png\" alt=\"\" width=\"640\" height=\"360\" srcset=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-wiring-diagram.png 640w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-wiring-diagram-300x169.png 300w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-wiring-diagram-65x37.png 65w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-wiring-diagram-225x127.png 225w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-wiring-diagram-350x197.png 350w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" \/><figcaption id=\"caption-attachment-120\" class=\"wp-caption-text\">Wiring diagram of an SPST switch circuit<\/figcaption><\/figure>\n","protected":false},"author":103,"menu_order":2,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["alee59"],"pb_section_license":"all-rights-reserved"},"chapter-type":[],"contributor":[61],"license":[58],"class_list":["post-123","chapter","type-chapter","status-publish","hentry","contributor-alee59","license-all-rights-reserved"],"part":117,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/123","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/users\/103"}],"version-history":[{"count":3,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/123\/revisions"}],"predecessor-version":[{"id":424,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/123\/revisions\/424"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/parts\/117"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/123\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/media?parent=123"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapter-type?post=123"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/contributor?post=123"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/license?post=123"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}