{"id":26478,"date":"2026-05-28T18:19:06","date_gmt":"2026-05-28T10:19:06","guid":{"rendered":"https:\/\/www.bestpcbs.com\/blog\/?p=26478"},"modified":"2026-05-28T18:29:42","modified_gmt":"2026-05-28T10:29:42","slug":"switch-spdt-symbol","status":"publish","type":"post","link":"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/","title":{"rendered":"Switch SPDT Symbol: Meaning, Diagram &#038; How to Read It"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#What_Is_a_SPDT_Switch_Single_Pole_Double_Throw_Explained\" >What Is a SPDT Switch? (Single Pole, Double Throw Explained)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#What_Is_the_Symbol_for_a_SPDT_Switch\" >What Is the Symbol for a SPDT Switch?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#How_to_Read_a_SPDT_Switch_Symbol_The_Pole_and_Two_Throw_Terminals\" >How to Read a SPDT Switch Symbol: The Pole and Two Throw Terminals<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#SPDT_Switch_Schematic_Symbol_IEC_vs_ANSIIEEE_Standards\" >SPDT Switch Schematic Symbol: IEC vs ANSI\/IEEE Standards<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#SPDT_Symbol_for_Different_Switch_Types_Toggle_Slide_Limit_Pressure\" >SPDT Symbol for Different Switch Types: Toggle, Slide, Limit &amp; Pressure<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#SPDT_vs_SPST_vs_DPDT_Switch_Symbols_Compared\" >SPDT vs SPST vs DPDT: Switch Symbols Compared<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#SPDT_Relay_Symbol_vs_SPDT_Switch_Symbol\" >SPDT Relay Symbol vs SPDT Switch Symbol<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#How_to_Draw_a_SPDT_Switch_Symbol_Step_by_Step\" >How to Draw a SPDT Switch Symbol Step by Step<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/#FAQs_About_Switch_SPDT_Symbol\" >FAQs About Switch SPDT Symbol<\/a><\/li><\/ul><\/nav><\/div>\n<div class=\"yzp-no-index\"><\/div>\n<p>The <a href=\"https:\/\/www.bestpcbs.com\/blog\/2026\/05\/switch-spdt-symbol\/\" title=\"\">switch SPDT symbol <\/a>appears in almost every schematic that routes a signal between two destinations. It looks simple\u2014one input arm pointing at two contacts\u2014but reading it correctly tells you exactly how current flows through the circuit. This guide explains what the symbol means, how to read it, the IEC vs ANSI versions, and how to draw it yourself.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-2.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-2-1024x768.jpg\" alt=\"Figure 1: The basic Switch SPDT Symbol\u2014 one common (pole) terminal and two throw terminals.\" class=\"wp-image-26479\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-2-1024x768.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-2-300x225.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-2-768x576.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-2.jpg 1448w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_a_SPDT_Switch_Single_Pole_Double_Throw_Explained\"><\/span><strong>What Is a SPDT Switch? (Single Pole, Double Throw Explained)<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>SPDT stands for Single Pole, Double Throw. In plain terms:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Single pole \u2192 one common input terminal (the &#8220;pole&#8221;).<\/li>\n\n\n\n<li>Double throw \u2192 that input can connect to one of two output terminals.<\/li>\n<\/ul>\n\n\n\n<p>So a SPDT switch has three terminals and acts as a changeover (or selector): it sends the common line to output A or output B, but never both at once. In British English, a SPDT used to control one light from two locations is called a two-way switch.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"What_Is_the_Symbol_for_a_SPDT_Switch\"><\/span><strong>What Is the Symbol for a SPDT Switch?<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The SPDT switch symbol is a single line (the moving contact) that pivots from one common terminal toward two separate contacts. The common terminal is the pole; the two contacts are the throws. The position of the arm shows which throw the pole is connected to.<\/p>\n\n\n\n<p>You&#8217;ll also see it called a SPDT schematic symbol or SPDT circuit symbol\u2014they all refer to the same thing.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-3.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-3-1024x768.jpg\" alt=\"Figure 2: A labeled SPDT switch symbol showing the COM, NC, and NO terminals.\" class=\"wp-image-26480\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-3-1024x768.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-3-300x225.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-3-768x576.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-3.jpg 1448w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_to_Read_a_SPDT_Switch_Symbol_The_Pole_and_Two_Throw_Terminals\"><\/span><strong>How to Read a SPDT Switch Symbol: The Pole and Two Throw Terminals<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>Read it in three steps:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Find the common terminal (pole). It&#8217;s the single terminal the moving arm starts from\u2014usually drawn as a dot or short line. This is your input.<\/li>\n\n\n\n<li>Find the two throw terminals. These are the two contacts the arm can reach. They&#8217;re your two possible outputs.<\/li>\n\n\n\n<li>Look at where the arm points. The arm shows the switch&#8217;s current state\u2014connected to the upper throw or the lower throw.<\/li>\n<\/ol>\n\n\n\n<p>The three terminals are commonly labeled:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>COM \u2014 the common (pole)<\/li>\n\n\n\n<li>NC \u2014 normally closed (connected to COM when the switch is at rest)<\/li>\n\n\n\n<li>NO \u2014 normally open (connects to COM when the switch is actuated)<\/li>\n<\/ul>\n\n\n\n<p>A SPDT is break-before-make by default: the arm leaves one throw before touching the other, so the two outputs are never shorted together.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"SPDT_Switch_Schematic_Symbol_IEC_vs_ANSIIEEE_Standards\"><\/span><strong>SPDT Switch Schematic Symbol: IEC vs ANSI\/IEEE Standards<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The SPDT symbol is nearly universal, but two standards govern the fine details:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>IEC 60617 (international \/ European): draws the contacts as short bars or open marks, with a clean pivoting line for the moving contact.<\/li>\n\n\n\n<li>ANSI\/IEEE 315 (North American): very similar, typically with small open circles or dots for the contact points.<\/li>\n<\/ul>\n\n\n\n<p>In both standards the logic is identical\u2014one pole, two throws\u2014so a schematic is readable either way. The differences are cosmetic: the shape of the contact points and the angle of the actuator line.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-4.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-4-1024x768.jpg\" alt=\"Figure 3: The SPDT switch symbol in IEC 60617 and ANSI\/IEEE 315 styles.\" class=\"wp-image-26481\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-4-1024x768.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-4-300x225.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-4-768x576.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-4.jpg 1448w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"SPDT_Symbol_for_Different_Switch_Types_Toggle_Slide_Limit_Pressure\"><\/span><strong>SPDT Symbol for Different Switch Types: Toggle, Slide, Limit &amp; Pressure<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The same SPDT symbol is used no matter the physical switch, because the symbol describes the function (one pole, two throws), not the actuator. The actuator may be shown with an extra mark:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>SPDT toggle switch symbol \u2014 the standard pivoting-arm symbol; the most common form.<\/li>\n\n\n\n<li>SPDT slide switch symbol \u2014 same contacts, sometimes drawn with a small slider mark.<\/li>\n\n\n\n<li>SPDT limit switch symbol \u2014 the arm gains a small roller\/lever or actuator flag to show it&#8217;s mechanically tripped.<\/li>\n\n\n\n<li>SPDT pressure switch symbol \u2014 the actuator is drawn as a diaphragm or pressure symbol that moves the contact.<\/li>\n<\/ul>\n\n\n\n<p>The takeaway: find the pole and the two throws first\u2014the extra marks just tell you how the switch is operated.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-5.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-5-1024x768.jpg\" alt=\"Figure 4: SPDT symbol variations for toggle, slide, limit, and pressure switches.\" class=\"wp-image-26482\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-5-1024x768.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-5-300x225.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-5-768x576.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-5.jpg 1448w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"SPDT_vs_SPST_vs_DPDT_Switch_Symbols_Compared\"><\/span><strong>SPDT vs SPST vs DPDT: Switch Symbols Compared<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>These three are easy to tell apart once you count poles and throws:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>SPST (Single Pole, Single Throw) \u2014 1 pole, 1 throw, 2 terminals. A simple on\/off switch; the symbol is one arm and one contact.<\/li>\n\n\n\n<li>SPDT (Single Pole, Double Throw) \u2014 1 pole, 2 throws, 3 terminals. One arm selecting between two contacts.<\/li>\n\n\n\n<li>DPDT (Double Pole, Double Throw) \u2014 two SPDT switches operated together, 6 terminals. Drawn as two SPDT symbols joined by a dashed line showing the poles move as one.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-6.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-6-1024x768.jpg\" alt=\"Figure 5: SPST vs SPDT vs DPDT switch symbols compared, with terminal counts.\" class=\"wp-image-26483\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-6-1024x768.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-6-300x225.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-6-768x576.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-6.jpg 1448w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<p>Comparison table:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Switch Type<\/th><th class=\"has-text-align-center\" data-align=\"center\">Poles<\/th><th class=\"has-text-align-center\" data-align=\"center\">Throws<\/th><th class=\"has-text-align-center\" data-align=\"center\">Terminals<\/th><th class=\"has-text-align-center\" data-align=\"center\">Symbol Cue<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">SPST<\/td><td class=\"has-text-align-center\" data-align=\"center\">1<\/td><td class=\"has-text-align-center\" data-align=\"center\">1<\/td><td class=\"has-text-align-center\" data-align=\"center\">2<\/td><td class=\"has-text-align-center\" data-align=\"center\">One arm, one contact<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">SPDT<\/td><td class=\"has-text-align-center\" data-align=\"center\">1<\/td><td class=\"has-text-align-center\" data-align=\"center\">2<\/td><td class=\"has-text-align-center\" data-align=\"center\">3<\/td><td class=\"has-text-align-center\" data-align=\"center\">One arm, two contacts<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">DPDT<\/td><td class=\"has-text-align-center\" data-align=\"center\">2<\/td><td class=\"has-text-align-center\" data-align=\"center\">2<\/td><td class=\"has-text-align-center\" data-align=\"center\">6<\/td><td class=\"has-text-align-center\" data-align=\"center\">Two SPDT symbols + dashed link<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"SPDT_Relay_Symbol_vs_SPDT_Switch_Symbol\"><\/span><strong>SPDT Relay Symbol vs SPDT Switch Symbol<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>A SPDT relay uses the same contact set as a manual SPDT switch\u2014often called a Form C contact\u2014but adds a coil. The symbol shows:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A coil (rectangle or loop) that, when energized, moves the contact.<\/li>\n\n\n\n<li>The SPDT contact set: COM, NC, and NO.<\/li>\n<\/ul>\n\n\n\n<p>When the coil is de-energized, COM connects to NC. Energize the coil, and COM switches to NO. So the difference between the switch and relay symbols is simply the added coil and the dashed line linking it to the moving contact.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-1.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-1-1024x768.jpg\" alt=\"Figure 6: The SPDT relay symbol \u2014 a coil plus Form C (COM\/NC\/NO) contacts.\" class=\"wp-image-26484\" srcset=\"https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-1-1024x768.jpg 1024w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-1-300x225.jpg 300w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-1-768x576.jpg 768w, https:\/\/www.bestpcbs.com\/blog\/wp-content\/uploads\/2026\/05\/switch-spdt-symbol-1.jpg 1448w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"How_to_Draw_a_SPDT_Switch_Symbol_Step_by_Step\"><\/span><strong>How to Draw a SPDT Switch Symbol Step by Step<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>You can sketch a correct SPDT symbol in four steps:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Draw the common terminal (pole) as a dot or short line on the left\u2014this is the input.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Draw two throw contacts on the right, one above the other\u2014these are the two outputs.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Add the moving arm from the pole, angled so it touches one of the two throws.<\/li>\n<\/ul>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Label the terminals: COM on the pole, NC and NO on the two throws.<\/li>\n<\/ul>\n\n\n\n<p>For a DPDT, draw two of these stacked and connect the poles with a dashed line. For a relay, add a coil and link it to the arm with a dashed line.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"FAQs_About_Switch_SPDT_Symbol\"><\/span><strong>FAQs About Switch SPDT Symbol<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p><strong>How many terminals does a SPDT switch have? <\/strong><br>Three: one common (COM\/pole) and two throws (often labeled NC and NO).<\/p>\n\n\n\n<p><strong>What do COM, NO, and NC mean on a SPDT symbol? <\/strong><br>COM is the common pole (input). NC (normally closed) is connected to COM at rest. NO (normally open) connects to COM when the switch is actuated.<\/p>\n\n\n\n<p><strong>Is a SPDT switch the same as a changeover switch? <\/strong><br>Yes. &#8220;Changeover&#8221; and &#8220;two-way switch&#8221; (British English) both describe a SPDT switch.<\/p>\n\n\n\n<p><strong>What&#8217;s the difference between the SPST and SPDT symbols? <\/strong><br>SPST has one arm and one contact (2 terminals, on\/off). SPDT has one arm and two contacts (3 terminals, selects between two outputs).<\/p>\n\n\n\n<p><strong>Can a SPDT switch be used as a SPST switch? <\/strong><br>Yes\u2014just use the common terminal and one throw, and leave the other throw unconnected.<\/p>\n\n\n\n<p><strong>Is a 2-way switch the same as SPDT? <\/strong><br>Yes. &#8220;2-way switch&#8221; is the common British term for a SPDT switch, often used in staircase lighting.<\/p>\n\n\n\n<p>Designing a <a href=\"https:\/\/www.bestpcbs.com\/blog\/2025\/05\/electronic-pcb-board-manufacturer-no-moq\/\" title=\"\">electronic PCB board <\/a>that uses SPDT switches, relays, or other components? EBest Circuit (Best Technology) is a one-stop PCB &amp; PCBA contract manufacturer\u2014send your Gerber files and BOM to <strong>sales@bestpcbs.com<\/strong> for a free DFM review.<\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The switch SPDT symbol appears in almost every schematic that routes a signal between two destinations. It looks simple\u2014one input arm pointing at two contacts\u2014but reading it correctly tells you exactly how current flows through the circuit. This guide explains what the symbol means, how to read it, the IEC vs ANSI versions, and how [&hellip;]<\/p>\n","protected":false},"author":33085,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"footnotes":""},"categories":[175,174,5341],"tags":[5872,5873,5874,5870],"class_list":["post-26478","post","type-post","status-publish","format-standard","hentry","category-best-pcb","category-bestpcb","category-electrical-components","tag-schematic-symbols","tag-spdt-switch","tag-spdt-switch-symbol-2","tag-switch-spdt-symbol"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/26478","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/users\/33085"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/comments?post=26478"}],"version-history":[{"count":3,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/26478\/revisions"}],"predecessor-version":[{"id":26491,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/posts\/26478\/revisions\/26491"}],"wp:attachment":[{"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/media?parent=26478"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/categories?post=26478"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bestpcbs.com\/blog\/wp-json\/wp\/v2\/tags?post=26478"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}