{"id":89,"date":"2021-03-23T19:31:45","date_gmt":"2021-03-23T23:31:45","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/chapter\/single-pole-single-throw-spst\/"},"modified":"2021-04-21T14:47:24","modified_gmt":"2021-04-21T18:47:24","slug":"single-pole-single-throw-spst","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/chapter\/single-pole-single-throw-spst\/","title":{"raw":"Single-pole, single-throw (SPST)","rendered":"Single-pole, single-throw (SPST)"},"content":{"raw":"This switch is used where we only need to break a single line in a 120V single-phase supply, providing that it is connected to an <strong>ungrounded <\/strong>circuit conductor. There are two wire connection terminals, one for the line voltage, and the other for the \u201cswitch leg\u201d to the lamp. It does not matter which wire is connected to which terminal as the switch acts as a simple \u201copen\/closed\u201d device.\r\n\r\n<img class=\"aligncenter wp-image-87 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-back.png\" alt=\"\" width=\"640\" height=\"360\" \/>\r\n\r\nWhen the external operating handle is operated the internal switching mechanism either opens or closes a single line contact and thus controls the flow of current through the device and any other series-connected loads.\r\n\r\nThe switch has a marked \u201con\u201d and \u201coff\u201d position and switches should be installed so that moving the handle upwards energizes the load, and moving the handle down de-energizes the load. As a general safety rule, gravity should never be able to accidentally energize a circuit.\r\n\r\n<img class=\"aligncenter wp-image-88 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-Front.png\" alt=\"\" width=\"654\" height=\"718\" \/>\r\n\r\n&nbsp;","rendered":"<p>This switch is used where we only need to break a single line in a 120V single-phase supply, providing that it is connected to an <strong>ungrounded <\/strong>circuit conductor. There are two wire connection terminals, one for the line voltage, and the other for the \u201cswitch leg\u201d to the lamp. It does not matter which wire is connected to which terminal as the switch acts as a simple \u201copen\/closed\u201d device.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-87 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-back.png\" alt=\"\" width=\"640\" height=\"360\" srcset=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-back.png 640w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-back-300x169.png 300w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-back-65x37.png 65w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-back-225x127.png 225w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/02\/SPST-back-350x197.png 350w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" \/><\/p>\n<p>When the external operating handle is operated the internal switching mechanism either opens or closes a single line contact and thus controls the flow of current through the device and any other series-connected loads.<\/p>\n<p>The switch has a marked \u201con\u201d and \u201coff\u201d position and switches should be installed so that moving the handle upwards energizes the load, and moving the handle down de-energizes the load. As a general safety rule, gravity should never be able to accidentally energize a circuit.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-88 size-full\" src=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-Front.png\" alt=\"\" width=\"654\" height=\"718\" srcset=\"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-Front.png 654w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-Front-273x300.png 273w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-Front-65x71.png 65w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-Front-225x247.png 225w, https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-content\/uploads\/sites\/1349\/2021\/03\/SPST-Front-350x384.png 350w\" sizes=\"auto, (max-width: 654px) 100vw, 654px\" \/><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"author":103,"menu_order":1,"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-89","chapter","type-chapter","status-publish","hentry","contributor-alee59","license-all-rights-reserved"],"part":85,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/89","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":4,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/89\/revisions"}],"predecessor-version":[{"id":410,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/89\/revisions\/410"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/parts\/85"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapters\/89\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/media?parent=89"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/pressbooks\/v2\/chapter-type?post=89"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/contributor?post=89"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/lightingforelectricians\/wp-json\/wp\/v2\/license?post=89"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}