{"id":27036,"date":"2024-12-30T18:37:41","date_gmt":"2024-12-30T10:37:41","guid":{"rendered":"https:\/\/cnspd.com\/?p=27036"},"modified":"2026-06-23T09:24:41","modified_gmt":"2026-06-23T01:24:41","slug":"spd-type1-vs-type2-vs-type-3","status":"publish","type":"post","link":"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/","title":{"rendered":"Type 1 vs Type 2 vs Type 3 SPD: What Is the Difference?"},"content":{"rendered":"<section class=\"l-section wpb_row height_large\"><div class=\"l-section-h i-cf\"><div class=\"g-cols vc_row via_grid cols_1 laptops-cols_inherit tablets-cols_inherit mobiles-cols_1 valign_top type_default stacking_default\"><div class=\"wpb_column vc_column_container\"><div class=\"vc_column-inner\"><div class=\"w-html us_custom_4f93c5c3\"><style>\n\/* =========================================================\n   LEEYEE ARTICLE CLEAN VERSION\n   Type 1 vs Type 2 vs Type 3 SPD\n   Use inside WordPress Custom 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var(--muted);\n}\n\n.leeyee-spd-related {\n  display: grid;\n  grid-template-columns: repeat(2, minmax(0, 1fr));\n  gap: 12px;\n  margin-top: 22px;\n}\n\n.leeyee-spd-related a {\n  display: block;\n  padding: 16px 17px;\n  border: 1px solid var(--line);\n  border-radius: 9px;\n  background: #fff;\n  color: var(--text) !important;\n  font-weight: 800;\n  text-decoration: none !important;\n}\n\n.leeyee-spd-related a:hover {\n  border-color: var(--blue);\n  color: var(--blue) !important;\n}\n\n.leeyee-spd-related span {\n  display: block;\n  margin-top: 5px;\n  color: var(--muted);\n  font-size: 13px;\n  font-weight: 400;\n}\n\n.leeyee-spd-cta {\n  margin-top: 8px;\n  padding: 22px;\n  border: 1px solid #cfe0ec;\n  border-radius: 12px;\n  background: var(--blue-pale);\n}\n\n.leeyee-spd-cta h2 {\n  margin-bottom: 8px;\n  font-size: 27px;\n}\n\n.leeyee-spd-btn {\n  display: inline-flex;\n  align-items: center;\n  justify-content: center;\n  min-height: 46px;\n  margin-top: 8px;\n  padding: 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 .leeyee-spd-table {\n    display: block !important;\n    min-width: 0 !important;\n    width: 100% !important;\n  }\n\n  .leeyee-spd-table thead {\n    display: none !important;\n  }\n\n  .leeyee-spd-table tbody {\n    display: grid !important;\n    gap: 14px !important;\n  }\n\n  .leeyee-spd-table tr {\n    display: block !important;\n    overflow: hidden !important;\n    border: 1px solid var(--line) !important;\n    border-radius: 12px !important;\n    background: #fff !important;\n  }\n\n  .leeyee-spd-table td {\n    display: block !important;\n    width: 100% !important;\n    padding: 12px 15px !important;\n    border-right: 0 !important;\n    border-bottom: 1px solid var(--line) !important;\n    font-size: 14px !important;\n    text-align: left !important;\n  }\n\n  .leeyee-spd-table td:last-child {\n    border-bottom: 0 !important;\n  }\n\n  .leeyee-spd-table td:first-child {\n    background: var(--blue) !important;\n    color: #fff !important;\n    font-size: 16px !important;\n    font-weight: 800 !important;\n  }\n\n  .leeyee-spd-table td:not(:first-child)::before {\n    display: block !important;\n    margin-bottom: 4px !important;\n    color: var(--blue) !important;\n    font-size: 12px !important;\n    font-weight: 800 !important;\n    text-transform: uppercase !important;\n    letter-spacing: .04em !important;\n  }\n\n  #quick-comparison .leeyee-spd-table td:nth-child(2)::before {\n    content: \"Typical position\";\n  }\n\n  #quick-comparison .leeyee-spd-table td:nth-child(3)::before {\n    content: \"Main protection role\";\n  }\n\n  #quick-comparison .leeyee-spd-table td:nth-child(4)::before {\n    content: \"Principal test duty\";\n  }\n\n  #quick-comparison .leeyee-spd-table td:nth-child(5)::before {\n    content: \"Common key rating\";\n  }\n\n  #technical-comparison .leeyee-spd-table td:nth-child(2)::before {\n    content: \"Type 1 SPD\";\n  }\n\n  #technical-comparison .leeyee-spd-table td:nth-child(3)::before {\n    content: \"Type 2 SPD\";\n  }\n\n  #technical-comparison .leeyee-spd-table td:nth-child(4)::before {\n    content: \"Type 3 SPD\";\n  }\n}\n\n@media (max-width: 600px) {\n  .leeyee-spd-article {\n    font-size: 15px;\n  }\n\n  .leeyee-spd-article section {\n    padding: 36px 0;\n  }\n\n  .leeyee-spd-intro {\n    padding-top: 4px;\n    padding-bottom: 26px;\n  }\n\n  .leeyee-spd-lead {\n    font-size: 16px;\n  }\n\n  .leeyee-spd-direct {\n    padding: 15px 16px;\n    font-size: 14px;\n  }\n\n  .leeyee-spd-toc {\n    padding: 19px;\n  }\n\n  .leeyee-spd-toc-grid,\n  .leeyee-spd-rating-list,\n  .leeyee-spd-related {\n    grid-template-columns: 1fr;\n  }\n\n  .leeyee-spd-cta {\n    padding: 19px;\n  }\n\n  .leeyee-spd-btn {\n    width: 100%;\n  }\n}\n<\/style>\n\n<article class=\"leeyee-spd-article\">\n\n  <div class=\"leeyee-spd-intro\">\n    <div class=\"leeyee-spd-label\">SPD Classification Guide<\/div>\n\n    <p class=\"leeyee-spd-lead\">\n      Compare Type 1, Type 2 and Type 3 surge protective devices by installation\n      position, test waveform, current rating and protection role.\n    <\/p>\n\n    <div class=\"leeyee-spd-direct\">\n      <strong>Direct answer:<\/strong>\n      Type 1 SPDs discharge high-energy lightning impulse current at the origin\n      of an installation. Type 2 SPDs limit induced lightning and switching\n      surges in distribution boards. Type 3 SPDs provide final protection close\n      to sensitive equipment.\n    <\/div>\n  <\/div>\n\n  <section id=\"contents\">\n    <div class=\"leeyee-spd-toc\">\n      <div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-custom 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\"><\/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=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#find-the-information-you-need\" >Find the Information You Need<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#type-1-type-2-and-type-3-spd-quick-comparison\" >Type 1, Type 2 and Type 3 SPD Quick Comparison<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#what-is-a-type-1-surge-protective-device\" >What Is a Type 1 Surge Protective Device?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#what-is-a-type-2-surge-protective-device\" >What Is a Type 2 Surge Protective Device?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#what-is-a-type-3-surge-protective-device\" >What Is a Type 3 Surge Protective Device?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#technical-comparison-type-1-vs-type-2-vs-type-3\" >Technical Comparison: Type 1 vs Type 2 vs Type 3<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#10350-%ce%bcs-vs-820-%ce%bcs-why-the-test-waveform-matters\" >10\/350 \u03bcs vs 8\/20 \u03bcs: Why the Test Waveform Matters<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#iimp-vs-in-vs-imax-vs-uoc\" >Iimp vs In vs Imax vs Uoc<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#how-type-1-type-2-and-type-3-spds-work-together\" >How Type 1, Type 2 and Type 3 SPDs Work Together<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#what-is-a-type-12-combined-spd\" >What Is a Type 1+2 Combined SPD?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#which-spd-type-do-you-need\" >Which SPD Type Do You Need?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#how-to-select-the-correct-spd-type\" >How to Select the Correct SPD Type<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#common-spd-selection-mistakes\" >Common SPD Selection Mistakes<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#iec-and-ul-spd-types-are-not-identical-definitions\" >IEC and UL SPD Types Are Not Identical Definitions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#type-1-vs-type-2-vs-type-3-spd-faq\" >Type 1 vs Type 2 vs Type 3 SPD FAQ<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#related-surge-protection-guides\" >Related Surge Protection Guides<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"#\" data-href=\"https:\/\/www.cnspd.com\/pt\/spd-tipo-1-vs-tipo-2-vs-tipo-3\/#need-help-selecting-the-correct-spd-type\" >Need Help Selecting the Correct SPD Type?<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"find-the-information-you-need\"><\/span>Find the Information You Need<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n      <div class=\"leeyee-spd-toc-grid\">\n        <a href=\"#quick-comparison\">Quick comparison<\/a>\n        <a href=\"#type-1-spd\">What is Type 1 SPD?<\/a>\n        <a href=\"#type-2-spd\">What is Type 2 SPD?<\/a>\n        <a href=\"#type-3-spd\">What is Type 3 SPD?<\/a>\n        <a href=\"#technical-comparison\">Technical comparison<\/a>\n        <a href=\"#waveforms\">10\/350 vs 8\/20 \u03bcs<\/a>\n        <a href=\"#ratings\">Iimp, In, Imax and Uoc<\/a>\n        <a href=\"#coordination\">How the types work together<\/a>\n        <a href=\"#type-1-2\">What is Type 1+2?<\/a>\n        <a href=\"#selection-guide\">Which SPD do you need?<\/a>\n        <a href=\"#selection-steps\">How to select an SPD<\/a>\n        <a href=\"#common-mistakes\">Common mistakes<\/a>\n        <a href=\"#iec-vs-ul\">IEC vs UL types<\/a>\n        <a href=\"#faq\">Frequently asked questions<\/a>\n        <a href=\"#request-selection\">Request model selection<\/a>\n      <\/div>\n    <\/div>\n  <\/section>\n\n  <section id=\"quick-comparison\">\n    <h2><span class=\"ez-toc-section\" id=\"type-1-type-2-and-type-3-spd-quick-comparison\"><\/span>Type 1, Type 2 and Type 3 SPD Quick Comparison<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      The easiest way to understand the three SPD types is to connect each type\n      with its normal position in the electrical installation.\n    <\/p>\n\n    <div class=\"leeyee-spd-table-wrap\">\n      <table class=\"leeyee-spd-table\">\n        <thead>\n          <tr>\n            <th>SPD type<\/th>\n            <th>Typical position<\/th>\n            <th>Main protection role<\/th>\n            <th>Principal test duty<\/th>\n            <th>Common key rating<\/th>\n          <\/tr>\n        <\/thead>\n        <tbody>\n          <tr>\n            <td>Type 1<\/td>\n            <td>Origin or main incoming board<\/td>\n            <td>Discharges high-energy partial lightning current<\/td>\n            <td>10\/350 \u03bcs impulse current<\/td>\n            <td>Iimp<\/td>\n          <\/tr>\n          <tr>\n            <td>Type 2<\/td>\n            <td>Main or sub-distribution board<\/td>\n            <td>Limits induced lightning and switching surges<\/td>\n            <td>8\/20 \u03bcs discharge current<\/td>\n            <td>In and Imax<\/td>\n          <\/tr>\n          <tr>\n            <td>Type 3<\/td>\n            <td>Close to sensitive terminal equipment<\/td>\n            <td>Limits remaining residual overvoltage<\/td>\n            <td>Combination-wave test<\/td>\n            <td>Uoc and Up<\/td>\n          <\/tr>\n        <\/tbody>\n      <\/table>\n    <\/div>\n\n    <div class=\"leeyee-spd-note\">\n      <strong>Simple protection path:<\/strong>\n      incoming supply \u2192 main distribution \u2192 sensitive equipment normally\n      corresponds to Type 1 \u2192 Type 2 \u2192 Type 3.\n    <\/div>\n  <\/section>\n\n  <section id=\"type-1-spd\">\n    <h2><span class=\"ez-toc-section\" id=\"what-is-a-type-1-surge-protective-device\"><\/span>What Is a Type 1 Surge Protective Device?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      A Type 1 SPD is designed for installation where partial lightning current\n      may enter the low-voltage electrical system.\n    <\/p>\n\n    <p>\n      It is commonly considered at the origin of an installation, particularly\n      where the building has an external lightning protection system or where\n      the incoming supply arrangement creates significant lightning-current\n      exposure.\n    <\/p>\n\n    <h3>What does a Type 1 SPD do?<\/h3>\n\n    <p>\n      A Type 1 SPD diverts high-energy impulse current toward the equipotential\n      bonding and earthing system. Its main role is to prevent lightning current\n      from passing uncontrolled through the internal electrical installation.\n    <\/p>\n\n    <h3>Type 1 test waveform<\/h3>\n\n    <p>\n      Type 1 SPDs are tested using a <strong>10\/350 \u03bcs current impulse<\/strong>.\n      The main rating associated with this test is <strong>Iimp<\/strong>, or\n      impulse discharge current.\n    <\/p>\n\n    <p>\n      Iimp should not be compared directly with the Imax value of a Type 2 SPD\n      because the two ratings use different waveforms and represent different\n      test duties.\n    <\/p>\n\n    <h3>Where is a Type 1 SPD installed?<\/h3>\n\n    <ul>\n      <li>Service entrance;<\/li>\n      <li>Main low-voltage switchboard;<\/li>\n      <li>Origin of the electrical installation;<\/li>\n      <li>Lightning protection zone transition where partial lightning current is expected.<\/li>\n    <\/ul>\n\n    <h3>When should Type 1 be considered?<\/h3>\n\n    <ul>\n      <li>The building has an external lightning protection system;<\/li>\n      <li>The incoming supply is exposed to lightning-current entry;<\/li>\n      <li>A project risk assessment identifies partial lightning current;<\/li>\n      <li>National installation rules specify Type 1 protection;<\/li>\n      <li>The installation is critical infrastructure with a defined lightning protection concept.<\/li>\n    <\/ul>\n\n    <div class=\"leeyee-spd-warning\">\n      <strong>Important limitation:<\/strong>\n      Type 1 primarily manages high-energy current. It does not automatically\n      guarantee sufficiently low residual voltage at every distant or sensitive load.\n    <\/div>\n  <\/section>\n\n  <section id=\"type-2-spd\">\n    <h2><span class=\"ez-toc-section\" id=\"what-is-a-type-2-surge-protective-device\"><\/span>What Is a Type 2 Surge Protective Device?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      A Type 2 SPD is the most common distribution-level surge protective device\n      in low-voltage electrical installations.\n    <\/p>\n\n    <p>\n      It limits transient overvoltages caused by indirect lightning effects,\n      switching operations and residual surge energy from an upstream protection stage.\n    <\/p>\n\n    <h3>What surge sources does Type 2 address?<\/h3>\n\n    <ul>\n      <li>Indirect lightning effects;<\/li>\n      <li>Switching operations;<\/li>\n      <li>Motors and transformers;<\/li>\n      <li>Utility-network disturbances;<\/li>\n      <li>Residual surge energy after an upstream SPD.<\/li>\n    <\/ul>\n\n    <h3>Type 2 test waveform<\/h3>\n\n    <p>\n      Type 2 SPDs are tested using the <strong>8\/20 \u03bcs current waveform<\/strong>.\n      Important ratings include <strong>In<\/strong>, <strong>Imax<\/strong>,\n      <strong>Up<\/strong> and <strong>Uc<\/strong>.\n    <\/p>\n\n    <h3>Where is a Type 2 SPD installed?<\/h3>\n\n    <ul>\n      <li>Main distribution boards;<\/li>\n      <li>Sub-distribution boards;<\/li>\n      <li>Machine-control cabinets;<\/li>\n      <li>Industrial panels;<\/li>\n      <li>Commercial electrical panels;<\/li>\n      <li>Solar inverter AC distribution panels.<\/li>\n    <\/ul>\n\n    <h3>When may Type 2 be sufficient?<\/h3>\n\n    <p>\n      A Type 2 SPD may be sufficient at the origin of some installations where\n      the system is not expected to carry partial lightning current.\n    <\/p>\n\n    <p>This may include certain installations with:<\/p>\n\n    <ul>\n      <li>Underground incoming supply;<\/li>\n      <li>No external lightning protection system;<\/li>\n      <li>Lower assessed lightning-current exposure;<\/li>\n      <li>No upstream Type 1 duty requirement.<\/li>\n    <\/ul>\n\n    <div class=\"leeyee-spd-note\">\n      This is not a universal rule. Final selection must follow the applicable\n      installation requirements and project risk assessment.\n    <\/div>\n  <\/section>\n\n  <section id=\"type-3-spd\">\n    <h2><span class=\"ez-toc-section\" id=\"what-is-a-type-3-surge-protective-device\"><\/span>What Is a Type 3 Surge Protective Device?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      A Type 3 SPD provides point-of-use protection for sensitive terminal equipment.\n      It limits residual surge voltage remaining after upstream protection or\n      developing along downstream conductors.\n    <\/p>\n\n    <h3>Where is Type 3 installed?<\/h3>\n\n    <p>Type 3 is installed close to protected equipment, including:<\/p>\n\n    <ul>\n      <li>PLCs;<\/li>\n      <li>Servers;<\/li>\n      <li>Control systems;<\/li>\n      <li>Communication equipment;<\/li>\n      <li>Medical equipment;<\/li>\n      <li>Sensitive power supplies;<\/li>\n      <li>Electronic household equipment.<\/li>\n    <\/ul>\n\n    <p>Type 3 protection may be built into socket outlets, power strips, equipment-protection modules, control-panel devices or terminal-protection units.<\/p>\n\n    <h3>Type 3 test method<\/h3>\n\n    <p>\n      Type 3 devices are commonly evaluated with a combination-wave generator\n      producing a 1.2\/50 \u03bcs open-circuit voltage waveform and an 8\/20 \u03bcs\n      short-circuit current waveform. Relevant ratings may include\n      <strong>Uoc<\/strong> and <strong>Up<\/strong>.\n    <\/p>\n\n    <h3>Can Type 3 be used alone?<\/h3>\n\n    <p>\n      Type 3 should not normally be expected to discharge the high surge energy\n      present at the service entrance or main distribution level.\n    <\/p>\n\n    <div class=\"leeyee-spd-warning\">\n      Type 3 is normally used as terminal protection within a coordinated system,\n      not as a substitute for correctly selected upstream protection.\n    <\/div>\n  <\/section>\n\n  <section id=\"technical-comparison\">\n    <h2><span class=\"ez-toc-section\" id=\"technical-comparison-type-1-vs-type-2-vs-type-3\"><\/span>Technical Comparison: Type 1 vs Type 2 vs Type 3<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <div class=\"leeyee-spd-table-wrap\">\n      <table class=\"leeyee-spd-table\">\n        <thead>\n          <tr>\n            <th>Comparison item<\/th>\n            <th>Type 1 SPD<\/th>\n            <th>Type 2 SPD<\/th>\n            <th>Type 3 SPD<\/th>\n          <\/tr>\n        <\/thead>\n        <tbody>\n          <tr>\n            <td>Main role<\/td>\n            <td>Lightning-current discharge<\/td>\n            <td>Distribution-level surge limitation<\/td>\n            <td>Final equipment protection<\/td>\n          <\/tr>\n          <tr>\n            <td>Typical position<\/td>\n            <td>Origin or main incoming board<\/td>\n            <td>Main or sub-distribution board<\/td>\n            <td>Close to terminal equipment<\/td>\n          <\/tr>\n          <tr>\n            <td>Test class<\/td>\n            <td>Class I<\/td>\n            <td>Class II<\/td>\n            <td>Class III<\/td>\n          <\/tr>\n          <tr>\n            <td>Principal waveform<\/td>\n            <td>10\/350 \u03bcs<\/td>\n            <td>8\/20 \u03bcs<\/td>\n            <td>Combination wave<\/td>\n          <\/tr>\n          <tr>\n            <td>Important rating<\/td>\n            <td>Iimp<\/td>\n            <td>In and Imax<\/td>\n            <td>Uoc<\/td>\n          <\/tr>\n          <tr>\n            <td>Also evaluate<\/td>\n            <td>Uc, Up and fault behaviour<\/td>\n            <td>Uc, Up and short-circuit rating<\/td>\n            <td>Up and load compatibility<\/td>\n          <\/tr>\n          <tr>\n            <td>Typical surge environment<\/td>\n            <td>Partial lightning current<\/td>\n            <td>Induced lightning and switching transients<\/td>\n            <td>Residual surge voltage<\/td>\n          <\/tr>\n          <tr>\n            <td>Can it protect the whole installation alone?<\/td>\n            <td>Not necessarily<\/td>\n            <td>Not necessarily<\/td>\n            <td>No<\/td>\n          <\/tr>\n          <tr>\n            <td>Common technology<\/td>\n            <td>Spark gap, MOV or combined technology<\/td>\n            <td>MOV-based or combined technology<\/td>\n            <td>Compact MOV, GDT or filter-based protection<\/td>\n          <\/tr>\n        <\/tbody>\n      <\/table>\n    <\/div>\n  <\/section>\n\n  <section id=\"waveforms\">\n    <h2><span class=\"ez-toc-section\" id=\"10350-%ce%bcs-vs-820-%ce%bcs-why-the-test-waveform-matters\"><\/span>10\/350 \u03bcs vs 8\/20 \u03bcs: Why the Test Waveform Matters<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      A current value shown in kiloamperes is meaningful only when the associated\n      waveform and rating definition are also known.\n    <\/p>\n\n    <div class=\"leeyee-spd-image\">\n      <img decoding=\"async\"\n        src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/06\/Waveform-comparison-for-SPD-selection.png\"\n        alt=\"10\/350 \u03bcs vs 8\/20 \u03bcs waveform comparison for SPD selection\"\n        loading=\"lazy\"\n      \/>\n      <div class=\"leeyee-spd-caption\">\n        The 10\/350 \u03bcs waveform is associated with Type 1 lightning-current duty,\n        while the 8\/20 \u03bcs waveform is associated with Type 2 discharge-current\n        testing. The kA value should always be read together with the waveform\n        and SPD classification.\n      <\/div>\n    <\/div>\n\n    <div class=\"leeyee-spd-note\">\n      Always compare the waveform, rating definition, current per protection mode,\n      voltage protection level and full SPD classification.\n    <\/div>\n  <\/section>\n\n  <section id=\"ratings\">\n    <h2><span class=\"ez-toc-section\" id=\"iimp-vs-in-vs-imax-vs-uoc\"><\/span>Iimp vs In vs Imax vs Uoc<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      These values describe different tests and should not be treated as\n      interchangeable versions of the same current rating.\n    <\/p>\n\n    <div class=\"leeyee-spd-rating-list\">\n      <div class=\"leeyee-spd-rating\">\n        <strong>Iimp<\/strong>\n        <span>Impulse discharge current associated with the Type 1 10\/350 \u03bcs test.<\/span>\n      <\/div>\n      <div class=\"leeyee-spd-rating\">\n        <strong>In<\/strong>\n        <span>Nominal discharge current associated with the Type 2 8\/20 \u03bcs test.<\/span>\n      <\/div>\n      <div class=\"leeyee-spd-rating\">\n        <strong>Imax<\/strong>\n        <span>Maximum discharge current associated with a Type 2 8\/20 \u03bcs test.<\/span>\n      <\/div>\n      <div class=\"leeyee-spd-rating\">\n        <strong>Uoc<\/strong>\n        <span>Open-circuit voltage of the combination-wave generator used for Type 3 testing.<\/span>\n      <\/div>\n    <\/div>\n\n    <p>\n      Other important values include Uc, Up, short-circuit current rating and\n      backup protection requirements.\n    <\/p>\n  <\/section>\n\n  <section id=\"coordination\">\n    <h2><span class=\"ez-toc-section\" id=\"how-type-1-type-2-and-type-3-spds-work-together\"><\/span>How Type 1, Type 2 and Type 3 SPDs Work Together<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      Effective surge protection is based on coordinated protection stages,\n      not simply on installing the SPD with the largest current rating.\n    <\/p>\n\n    <p>A typical concept may use:<\/p>\n\n    <ol>\n      <li><strong>Type 1<\/strong> at the origin to discharge partial lightning current;<\/li>\n      <li><strong>Type 2<\/strong> in a downstream distribution board to limit remaining overvoltage;<\/li>\n      <li><strong>Type 3<\/strong> near sensitive equipment to reduce final residual surge voltage.<\/li>\n    <\/ol>\n\n    <p>\n      This does not mean every building must use three separate SPDs. Possible\n      alternatives include Type 1+2 combined SPDs, Type 2+3 combined SPDs, or\n      Type 2 protection at the origin where Type 1 duty is not required.\n    <\/p>\n\n    <div class=\"leeyee-spd-warning\">\n      <strong>Is a 10-meter distance always required?<\/strong><br>\n      No single cable-distance rule should be applied to every SPD combination.\n      Required coordination depends on SPD technology, manufacturer-tested\n      coordination, conductor arrangement, protection levels and the protected equipment.\n    <\/div>\n  <\/section>\n\n  <section id=\"type-1-2\">\n    <h2><span class=\"ez-toc-section\" id=\"what-is-a-type-12-combined-spd\"><\/span>What Is a Type 1+2 Combined SPD?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      A Type 1+2 SPD is tested for both Type 1\/Class I and Type 2\/Class II duties.\n      It combines lightning impulse-current discharge and distribution-level\n      surge-voltage limitation.\n    <\/p>\n\n    <p>A Type 1+2 SPD may be useful where:<\/p>\n\n    <ul>\n      <li>Both protection duties are required at one installation point;<\/li>\n      <li>Main-board space is limited;<\/li>\n      <li>Separate SPD coordination would be difficult;<\/li>\n      <li>A compact internally coordinated solution is preferred.<\/li>\n    <\/ul>\n\n    <div class=\"leeyee-spd-note\">\n      Type 1+2 does not automatically mean no downstream protection is required.\n      Remote panels and sensitive equipment may still need additional coordinated\n      Type 2 or Type 3 protection.\n    <\/div>\n\n    <p>\n      For complete Type 1+2 selection guidance, see the dedicated\n      <a href=\"https:\/\/www.cnspd.com\/type-1-2-spd\/\" target=\"_blank\" rel=\"noopener\">Type 1+2 SPD guide<\/a>.\n    <\/p>\n  <\/section>\n\n  <section id=\"selection-guide\">\n    <h2><span class=\"ez-toc-section\" id=\"which-spd-type-do-you-need\"><\/span>Which SPD Type Do You Need?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      The following table provides an initial direction. Final selection must\n      still follow the actual system design and applicable requirements.\n    <\/p>\n\n    <div class=\"leeyee-spd-table-wrap\">\n      <table class=\"leeyee-spd-table\">\n        <thead>\n          <tr>\n            <th>Project situation<\/th>\n            <th>Initial selection direction<\/th>\n          <\/tr>\n        <\/thead>\n        <tbody>\n          <tr>\n            <td>Building has an external lightning protection system<\/td>\n            <td>Consider Type 1 or Type 1+2<\/td>\n          <\/tr>\n          <tr>\n            <td>Partial lightning current may enter the installation<\/td>\n            <td>Type 1 duty is required<\/td>\n          <\/tr>\n          <tr>\n            <td>General main-panel protection without Type 1 duty<\/td>\n            <td>Type 2<\/td>\n          <\/tr>\n          <tr>\n            <td>Sub-distribution or machine-control panel<\/td>\n            <td>Type 2<\/td>\n          <\/tr>\n          <tr>\n            <td>Sensitive terminal equipment<\/td>\n            <td>Type 3 near the equipment<\/td>\n          <\/tr>\n          <tr>\n            <td>Type 1 and Type 2 duties are required in one main board<\/td>\n            <td>Type 1+2<\/td>\n          <\/tr>\n          <tr>\n            <td>Equipment is far from the main SPD<\/td>\n            <td>Consider additional Type 2 or Type 3<\/td>\n          <\/tr>\n          <tr>\n            <td>Surge protection is required on a solar PV DC circuit<\/td>\n            <td>Use a PV-specific DC SPD<\/td>\n          <\/tr>\n        <\/tbody>\n      <\/table>\n    <\/div>\n  <\/section>\n\n  <section id=\"selection-steps\">\n    <h2><span class=\"ez-toc-section\" id=\"how-to-select-the-correct-spd-type\"><\/span>How to Select the Correct SPD Type<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <ol>\n      <li><strong>Identify the installation position.<\/strong> Is the SPD installed at the origin, distribution board, machine panel or terminal equipment?<\/li>\n      <li><strong>Assess lightning exposure.<\/strong> Check the external lightning protection system, incoming supply and lightning protection zones.<\/li>\n      <li><strong>Confirm AC or DC application.<\/strong> Do not use a normal AC SPD on the DC side of a photovoltaic system.<\/li>\n      <li><strong>Confirm the earthing system.<\/strong> Identify TN-S, TN-C, TT, IT or the relevant DC grounding arrangement.<\/li>\n      <li><strong>Check the full rating set.<\/strong> Review Uc, Up, Iimp, In, Imax, Uoc, short-circuit rating and backup protection.<\/li>\n      <li><strong>Verify coordination.<\/strong> Check the relationship between upstream protection, downstream SPDs and protected equipment.<\/li>\n    <\/ol>\n  <\/section>\n\n  <section id=\"common-mistakes\">\n    <h2><span class=\"ez-toc-section\" id=\"common-spd-selection-mistakes\"><\/span>Common SPD Selection Mistakes<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <ul>\n      <li><strong>Choosing only by the largest kA value.<\/strong> A larger current number does not correct the wrong waveform, voltage rating or circuit configuration.<\/li>\n      <li><strong>Comparing Iimp directly with Imax.<\/strong> These values represent different test duties and different waveforms.<\/li>\n      <li><strong>Using Type 3 as the main building SPD.<\/strong> Type 3 is intended for final equipment protection, not high-energy incoming surge current.<\/li>\n      <li><strong>Assuming Type 1 protects every load.<\/strong> Residual voltage and downstream conductor effects may still require additional protection.<\/li>\n      <li><strong>Using a fixed 10-meter rule.<\/strong> Coordination must follow the selected SPD technologies and manufacturer documentation.<\/li>\n      <li><strong>Ignoring Uc and Up.<\/strong> Current capacity alone does not determine voltage compatibility or equipment protection.<\/li>\n      <li><strong>Using an AC SPD on PV DC.<\/strong> Photovoltaic DC circuits require application-specific voltage and disconnection characteristics.<\/li>\n      <li><strong>Ignoring short-circuit coordination.<\/strong> The SPD, backup fuse and prospective short-circuit current must be compatible.<\/li>\n    <\/ul>\n  <\/section>\n\n  <section id=\"iec-vs-ul\">\n    <h2><span class=\"ez-toc-section\" id=\"iec-and-ul-spd-types-are-not-identical-definitions\"><\/span>IEC and UL SPD Types Are Not Identical Definitions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <p>\n      IEC and UL systems both use Type 1, Type 2 and Type 3 terminology, but\n      the classifications should not be treated as fully interchangeable.\n    <\/p>\n\n    <p>\n      Under the IEC framework, the types are closely associated with test\n      classes, waveforms and protection duties. Under UL 1449, SPD types are\n      strongly related to the permitted connection location and installation\n      relative to service equipment and overcurrent protection.\n    <\/p>\n\n    <p>For North American projects, confirm:<\/p>\n\n    <ul>\n      <li>UL listing;<\/li>\n      <li>SPD type;<\/li>\n      <li>Nominal discharge current;<\/li>\n      <li>Voltage protection rating;<\/li>\n      <li>Short-circuit current rating;<\/li>\n      <li>Permitted connection location.<\/li>\n    <\/ul>\n\n    <div class=\"leeyee-spd-note\">\n      Do not convert IEC and UL classifications solely by matching the type number.\n    <\/div>\n  <\/section>\n\n  <section id=\"faq\">\n    <h2><span class=\"ez-toc-section\" id=\"type-1-vs-type-2-vs-type-3-spd-faq\"><\/span>Type 1 vs Type 2 vs Type 3 SPD FAQ<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <div class=\"leeyee-spd-faq\">\n      <details>\n        <summary>What is the main difference between Type 1, Type 2 and Type 3 SPD?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>Type 1 manages lightning-current duty at the origin, Type 2 provides distribution-level surge protection, and Type 3 limits residual surge voltage close to sensitive equipment.<\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Is Type 1 better than Type 2?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>No. They perform different roles. Type 1 handles lightning-current duty, while Type 2 limits transient overvoltage in the electrical distribution system.<\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Can Type 2 be installed at the main distribution board?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>Yes. Type 2 is commonly installed in main and sub-distribution boards where Type 1 lightning-current duty is not required or where an upstream Type 1 stage already exists.<\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Does every installation need a Type 1 SPD?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>No. The need for Type 1 depends on lightning-current exposure, external lightning protection, the incoming supply arrangement and applicable project requirements.<\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Can Type 3 SPD be used without Type 1 or Type 2?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>Type 3 should not normally be relied upon as the only protection where high-energy surges may enter the installation. It is intended primarily as coordinated terminal protection.<\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Is Type 1+2 the same as Type 1 and Type 2?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>A Type 1+2 SPD is tested for both Type 1 and Type 2 duties within one product. Separate Type 1 and Type 2 devices can provide the same stages, but their coordination must be verified.<\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>What is the difference between Iimp and Imax?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>Iimp is associated with the 10\/350 \u03bcs Type 1 impulse-current test. Imax is associated with the 8\/20 \u03bcs Type 2 maximum discharge-current test.<\/p>\n        <\/div>\n      <\/details>\n\n      <details>\n        <summary>Can LEEYEE help select the correct SPD type?<\/summary>\n        <div class=\"leeyee-spd-faq-body\">\n          <p>Yes. Provide the system voltage, AC or DC application, earthing arrangement, installation position, poles, required ratings and project quantity.<\/p>\n        <\/div>\n      <\/details>\n    <\/div>\n  <\/section>\n\n  <section>\n    <h2><span class=\"ez-toc-section\" id=\"related-surge-protection-guides\"><\/span>Related Surge Protection Guides<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n    <div class=\"leeyee-spd-related\">\n      <a href=\"https:\/\/www.cnspd.com\/shop\/surge-protective-device\/\" target=\"_blank\" rel=\"noopener\">Surge Protective Devices<span>Browse AC, DC, solar PV and signal surge protection products.<\/span><\/a>\n      <a href=\"https:\/\/www.cnspd.com\/type-1-2-spd\/\" target=\"_blank\" rel=\"noopener\">Type 1+2 SPD<span>Learn when combined Type 1 and Type 2 protection is suitable.<\/span><\/a>\n      <a href=\"https:\/\/www.cnspd.com\/solar-spd\/\" target=\"_blank\" rel=\"noopener\">Solar SPD<span>Understand surge protection selection for photovoltaic systems.<\/span><\/a>\n      <a href=\"https:\/\/www.cnspd.com\/dc-spd-up-to-1500v\/\" target=\"_blank\" rel=\"noopener\">1500V DC SPD<span>Explore surge protection for high-voltage PV DC systems.<\/span><\/a>\n    <\/div>\n  <\/section>\n\n  <section id=\"request-selection\">\n    <div class=\"leeyee-spd-cta\">\n      <h2><span class=\"ez-toc-section\" id=\"need-help-selecting-the-correct-spd-type\"><\/span>Need Help Selecting the Correct SPD Type?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n      <p>\n        Send the AC or DC application, system voltage, earthing arrangement,\n        installation position, required poles, current ratings and project quantity.\n        LEEYEE will help identify a suitable surge protection configuration.\n      <\/p>\n\n      <button type=\"button\" class=\"leeyee-spd-btn leeyee-site-popup-btn\" aria-label=\"Request SPD Selection\">\n        <span class=\"w-btn-label\">Request SPD Selection<\/span>\n      <\/button>\n    <\/div>\n  <\/section>\n\n<\/article>\n\n\n<script>\n  document.addEventListener('DOMContentLoaded', function () {\n    var articlePopupButtons = document.querySelectorAll('.leeyee-site-popup-btn');\n\n    articlePopupButtons.forEach(function (button) {\n      button.addEventListener('click', function () {\n        var realPopupTrigger = document.querySelector('.w-popup.ush_popup_1 .w-popup-trigger');\n\n        if (realPopupTrigger) {\n          realPopupTrigger.click();\n        } else {\n          window.open('https:\/\/www.cnspd.com\/contact\/', '_blank', 'noopener');\n        }\n      });\n    });\n  });\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the main difference between Type 1, Type 2 and Type 3 SPD?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Type 1 manages lightning-current duty at the origin, Type 2 provides distribution-level surge protection, and Type 3 limits residual surge voltage close to sensitive equipment.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is Type 1 better than Type 2?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"No. They perform different roles. Type 1 handles lightning-current duty, while Type 2 limits transient overvoltage in the electrical distribution system.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can Type 2 be installed at the main distribution board?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. Type 2 is commonly installed in main and sub-distribution boards where Type 1 lightning-current duty is not required or where an upstream Type 1 stage already exists.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Does every installation need a Type 1 SPD?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"No. The need for Type 1 depends on lightning-current exposure, external lightning protection, the incoming supply arrangement and applicable project requirements.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can Type 3 SPD be used without Type 1 or Type 2?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Type 3 should not normally be relied upon as the only protection where high-energy surges may enter the installation. It is intended primarily as coordinated terminal protection.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Is Type 1+2 the same as Type 1 and Type 2?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"A Type 1+2 SPD is tested for both Type 1 and Type 2 duties within one product. Separate Type 1 and Type 2 devices can provide the same stages, but their coordination must be verified.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"What is the difference between Iimp and Imax?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Iimp is associated with the 10\/350 microsecond Type 1 impulse-current test. Imax is associated with the 8\/20 microsecond Type 2 maximum discharge-current test.\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Can LEEYEE help select the correct SPD type?\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"Yes. Provide the system voltage, AC or DC application, earthing arrangement, installation position, poles, required ratings and project quantity.\"\n      }\n    }\n  ]\n}\n<\/script><\/div><\/div><\/div><\/div><\/div><\/section>\n","protected":false},"excerpt":{"rendered":"SPD Classification Guide Compare Type 1, Type 2 and Type 3 surge protective devices by installation position, test waveform, current rating and protection role. Direct answer: Type 1 SPDs discharge high-energy lightning impulse current at the origin of an installation. Type 2 SPDs limit induced lightning and switching surges in distribution boards. Type 3 SPDs...","protected":false},"author":18,"featured_media":25946,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,488,422],"tags":[],"class_list":["post-27036","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","category-surge-protection","category-industry-news"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Type 1 vs Type 2 vs Type 3 SPD: Differences &amp; Selection<\/title>\n<meta name=\"description\" content=\"Compare Type 1, Type 2 and Type 3 SPDs by installation position, test waveform, surge rating and application. 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