{"id":30391,"date":"2026-07-24T12:49:49","date_gmt":"2026-07-24T04:49:49","guid":{"rendered":"https:\/\/www.cnspd.com\/?p=30391"},"modified":"2026-07-24T14:43:52","modified_gmt":"2026-07-24T06:43:52","slug":"spd-tov-withstand-guide-for-oem-buyers-and-panel-builders","status":"publish","type":"post","link":"https:\/\/www.cnspd.com\/it\/spd-tov-withstand\/","title":{"rendered":"Guida alla resistenza SPD TOV per acquirenti OEM e costruttori di pannelli"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"30391\" class=\"elementor elementor-30391\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-6c7797a e-flex e-con-boxed e-con e-parent\" data-id=\"6c7797a\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-3fd443b elementor-widget elementor-widget-html\" data-id=\"3fd443b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t<style>\r\n#leeyee-spd-tov-withstand{\r\n  --tov-blue:#004898;\r\n  --tov-blue-dark:#00366f;\r\n  --tov-blue-soft:#eef5ff;\r\n  --tov-blue-pale:#f7fbff;\r\n  --tov-text:#293946;\r\n  --tov-heading:#172736;\r\n  --tov-muted:#607181;\r\n  --tov-border:#d8e2ec;\r\n  --tov-warning:#925300;\r\n  --tov-warning-bg:#fff8ea;\r\n  --tov-danger:#963333;\r\n  --tov-danger-bg:#fff5f5;\r\n  --tov-success:#2f7049;\r\n  --tov-success-bg:#f3faf6;\r\n  width:100%;\r\n  color:var(--tov-text);\r\n  font-size:17px;\r\n  line-height:1.72;\r\n  overflow-wrap:anywhere;\r\n}\r\n\r\n#leeyee-spd-tov-withstand,\r\n#leeyee-spd-tov-withstand *,\r\n#leeyee-spd-tov-withstand *::before,\r\n#leeyee-spd-tov-withstand *::after{\r\n  box-sizing:border-box;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-reading{\r\n  width:min(100%,850px);\r\n  margin:0 auto;\r\n}\r\n\r\n#leeyee-spd-tov-withstand p{\r\n  margin:0 0 18px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand strong{\r\n  color:var(--tov-heading);\r\n}\r\n\r\n#leeyee-spd-tov-withstand a{\r\n  color:var(--tov-blue);\r\n  text-decoration-thickness:1px;\r\n  text-underline-offset:3px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand a:hover{\r\n  color:var(--tov-blue-dark);\r\n}\r\n\r\n#leeyee-spd-tov-withstand sup{\r\n  font-size:.72em;\r\n  line-height:0;\r\n}\r\n\r\n#leeyee-spd-tov-withstand sup a{\r\n  text-decoration:none;\r\n}\r\n\r\n#leeyee-spd-tov-withstand h2{\r\n  margin:56px 0 19px;\r\n  color:var(--tov-heading);\r\n  font-size:31px;\r\n  line-height:1.26;\r\n  letter-spacing:-.02em;\r\n}\r\n\r\n#leeyee-spd-tov-withstand h3{\r\n  margin:33px 0 13px;\r\n  color:#203346;\r\n  font-size:23px;\r\n  line-height:1.35;\r\n}\r\n\r\n#leeyee-spd-tov-withstand h2 + p,\r\n#leeyee-spd-tov-withstand h3 + p{\r\n  margin-top:0;\r\n}\r\n\r\n#leeyee-spd-tov-withstand ul,\r\n#leeyee-spd-tov-withstand ol{\r\n  margin:0 0 22px;\r\n  padding-left:24px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand li{\r\n  margin:8px 0;\r\n  padding-left:3px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand section[id]{\r\n  scroll-margin-top:24px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-intro{\r\n  margin-bottom:20px;\r\n  color:#34485a;\r\n  font-size:18px;\r\n  line-height:1.7;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-scope{\r\n  margin:22px 0 29px;\r\n  padding:15px 18px;\r\n  border-left:4px solid var(--tov-blue);\r\n  background:var(--tov-blue-pale);\r\n  color:#405568;\r\n  font-size:15px;\r\n  line-height:1.63;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-quick{\r\n  margin:27px 0 25px;\r\n  padding:24px 25px;\r\n  border:1px solid #c8dbee;\r\n  border-radius:10px;\r\n  background:var(--tov-blue-pale);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-eyebrow{\r\n  display:block;\r\n  margin-bottom:7px;\r\n  color:var(--tov-blue);\r\n  font-size:13px;\r\n  font-weight:700;\r\n  letter-spacing:.08em;\r\n  text-transform:uppercase;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-quick h2{\r\n  margin:0 0 13px;\r\n  font-size:27px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-quick p:last-of-type{\r\n  margin-bottom:0;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-formula{\r\n  margin:19px 0 4px;\r\n  padding:14px 16px;\r\n  border:1px solid #bdd3e9;\r\n  border-radius:8px;\r\n  background:#fff;\r\n  color:#253c51;\r\n  font-size:18px;\r\n  font-weight:700;\r\n  text-align:center;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-formula span{\r\n  color:var(--tov-blue);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-answer-grid{\r\n  display:grid;\r\n  grid-template-columns:1fr 1fr;\r\n  gap:12px 22px;\r\n  margin:20px 0 0;\r\n  padding:0;\r\n  list-style:none;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-answer-grid li{\r\n  position:relative;\r\n  margin:0;\r\n  padding:0 0 0 23px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-answer-grid li::before{\r\n  content:\"\";\r\n  position:absolute;\r\n  top:.72em;\r\n  left:0;\r\n  width:8px;\r\n  height:8px;\r\n  border-radius:50%;\r\n  background:var(--tov-blue);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-figure{\r\n  width:min(100%,760px);\r\n  margin:28px auto 35px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-figure img{\r\n  display:block;\r\n  width:100%;\r\n  height:auto;\r\n  border:1px solid var(--tov-border);\r\n  border-radius:9px;\r\n  background:#fff;\r\n  box-shadow:0 5px 18px rgba(24,55,82,.07);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-figure figcaption{\r\n  margin-top:10px;\r\n  color:var(--tov-muted);\r\n  font-size:14px;\r\n  line-height:1.56;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-toc{\r\n  margin:29px 0 42px;\r\n  padding:21px 23px;\r\n  border:1px solid var(--tov-border);\r\n  border-radius:9px;\r\n  background:#fff;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-toc-title{\r\n  display:block;\r\n  margin-bottom:10px;\r\n  color:var(--tov-heading);\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-toc ol{\r\n  display:grid;\r\n  grid-template-columns:1fr 1fr;\r\n  gap:4px 28px;\r\n  margin:0;\r\n  padding-left:21px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-toc li{\r\n  margin:4px 0;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-toc a{\r\n  text-decoration:none;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-table-wrap{\r\n  width:100%;\r\n  margin:22px 0 13px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand table{\r\n  width:100%;\r\n  border-collapse:collapse;\r\n  table-layout:fixed;\r\n  background:#fff;\r\n  font-size:15px;\r\n  line-height:1.52;\r\n}\r\n\r\n#leeyee-spd-tov-withstand th,\r\n#leeyee-spd-tov-withstand td{\r\n  padding:13px 14px;\r\n  border:1px solid var(--tov-border);\r\n  text-align:left;\r\n  vertical-align:top;\r\n}\r\n\r\n#leeyee-spd-tov-withstand th{\r\n  background:var(--tov-blue);\r\n  color:#fff;\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand tbody tr:nth-child(even){\r\n  background:#fafcfe;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-table-note{\r\n  margin:9px 0 25px;\r\n  color:var(--tov-muted);\r\n  font-size:14px;\r\n  line-height:1.58;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-decision-table tbody tr:nth-child(1) td:first-child{\r\n  color:var(--tov-success);\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-decision-table tbody tr:nth-child(2) td:first-child{\r\n  color:var(--tov-warning);\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-decision-table tbody tr:nth-child(3) td:first-child{\r\n  color:var(--tov-danger);\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-meaning{\r\n  margin:21px 0 27px;\r\n  padding:16px 18px;\r\n  border-left:4px solid var(--tov-blue);\r\n  background:var(--tov-blue-pale);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-meaning strong{\r\n  display:block;\r\n  margin-bottom:4px;\r\n  color:var(--tov-blue-dark);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-warning{\r\n  margin:24px 0 28px;\r\n  padding:19px 20px;\r\n  border:1px solid #ead4ab;\r\n  border-left:4px solid var(--tov-warning);\r\n  border-radius:8px;\r\n  background:var(--tov-warning-bg);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-warning strong{\r\n  display:block;\r\n  margin-bottom:5px;\r\n  color:#724100;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-danger{\r\n  margin:24px 0 28px;\r\n  padding:19px 20px;\r\n  border:1px solid #eacaca;\r\n  border-left:4px solid var(--tov-danger);\r\n  border-radius:8px;\r\n  background:var(--tov-danger-bg);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-danger strong{\r\n  display:block;\r\n  margin-bottom:5px;\r\n  color:#782828;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-example{\r\n  margin:25px 0 29px;\r\n  padding:21px 22px;\r\n  border:1px solid #cdd9e4;\r\n  border-radius:9px;\r\n  background:#fff;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-example h3{\r\n  margin:0 0 13px;\r\n  font-size:22px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-example-label{\r\n  display:inline-block;\r\n  margin-bottom:12px;\r\n  padding:4px 9px;\r\n  border-radius:4px;\r\n  background:var(--tov-blue-soft);\r\n  color:var(--tov-blue-dark);\r\n  font-size:13px;\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-two-column{\r\n  display:grid;\r\n  grid-template-columns:1fr 1fr;\r\n  gap:20px;\r\n  margin:23px 0 29px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-small-panel{\r\n  padding:19px 20px;\r\n  border:1px solid var(--tov-border);\r\n  border-radius:9px;\r\n  background:#fff;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-small-panel h3{\r\n  margin:0 0 11px;\r\n  font-size:21px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-small-panel ul{\r\n  margin-bottom:0;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-steps{\r\n  margin:23px 0 28px;\r\n  padding:0;\r\n  counter-reset:tov-step;\r\n  list-style:none;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-steps li{\r\n  position:relative;\r\n  margin:0;\r\n  padding:17px 0 17px 53px;\r\n  border-bottom:1px solid var(--tov-border);\r\n  counter-increment:tov-step;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-steps li:first-child{\r\n  border-top:1px solid var(--tov-border);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-steps li::before{\r\n  content:counter(tov-step);\r\n  position:absolute;\r\n  top:17px;\r\n  left:0;\r\n  display:flex;\r\n  width:34px;\r\n  height:34px;\r\n  align-items:center;\r\n  justify-content:center;\r\n  border-radius:50%;\r\n  background:var(--tov-blue);\r\n  color:#fff;\r\n  font-size:15px;\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-steps strong{\r\n  display:block;\r\n  margin-bottom:3px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-checklist{\r\n  margin:26px 0 30px;\r\n  padding:23px 24px;\r\n  border:1px solid #c8dbee;\r\n  border-radius:10px;\r\n  background:var(--tov-blue-pale);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-checklist h3{\r\n  margin:0 0 14px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-check-grid{\r\n  display:grid;\r\n  grid-template-columns:1fr 1fr;\r\n  gap:7px 25px;\r\n  margin:0;\r\n  padding:0;\r\n  list-style:none;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-check-grid li{\r\n  position:relative;\r\n  margin:0;\r\n  padding:6px 0 6px 26px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-check-grid li::before{\r\n  content:\"\u2713\";\r\n  position:absolute;\r\n  left:0;\r\n  color:var(--tov-success);\r\n  font-weight:700;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-evidence{\r\n  margin:25px 0 29px;\r\n  padding:21px 22px;\r\n  border:1px solid var(--tov-border);\r\n  border-radius:9px;\r\n  background:#fff;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-evidence h3{\r\n  margin:0 0 13px;\r\n  font-size:22px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-evidence-list{\r\n  display:grid;\r\n  grid-template-columns:1fr 1fr;\r\n  gap:10px 24px;\r\n  margin:0;\r\n  padding:0;\r\n  list-style:none;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-evidence-list li{\r\n  position:relative;\r\n  margin:0;\r\n  padding:8px 0 8px 22px;\r\n  border-bottom:1px solid #edf1f4;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-evidence-list li::before{\r\n  content:\"\";\r\n  position:absolute;\r\n  top:1.08em;\r\n  left:0;\r\n  width:8px;\r\n  height:8px;\r\n  border:2px solid var(--tov-blue);\r\n  border-radius:2px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-cta{\r\n  margin:33px 0 44px;\r\n  padding:24px 25px;\r\n  border:1px solid #c8dbee;\r\n  border-radius:10px;\r\n  background:#fff;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-cta h2{\r\n  margin:0 0 10px;\r\n  font-size:27px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-cta p:last-of-type{\r\n  margin-bottom:19px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-faq{\r\n  margin-top:19px;\r\n  border-top:1px solid var(--tov-border);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-faq-item{\r\n  padding:22px 0 5px;\r\n  border-bottom:1px solid var(--tov-border);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-faq-item h3{\r\n  margin:0 0 9px;\r\n  font-size:21px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-related{\r\n  margin:31px 0 42px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-references{\r\n  margin-top:55px;\r\n  padding-top:25px;\r\n  border-top:2px solid var(--tov-border);\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-references h2{\r\n  margin-top:0;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-references ol{\r\n  padding-left:22px;\r\n}\r\n\r\n#leeyee-spd-tov-withstand .tov-references li{\r\n  margin:11px 0;\r\n  color:#4e5f6f;\r\n  font-size:14px;\r\n  line-height:1.58;\r\n}\r\n\r\n@media (max-width:768px){\r\n  #leeyee-spd-tov-withstand{\r\n    font-size:16px;\r\n    line-height:1.68;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand h2{\r\n    margin-top:46px;\r\n    font-size:28px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand h3{\r\n    font-size:21px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-intro{\r\n    font-size:17px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-answer-grid,\r\n  #leeyee-spd-tov-withstand .tov-toc ol,\r\n  #leeyee-spd-tov-withstand .tov-check-grid,\r\n  #leeyee-spd-tov-withstand .tov-evidence-list{\r\n    grid-template-columns:1fr;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-two-column{\r\n    grid-template-columns:1fr;\r\n    gap:14px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards,\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards tbody,\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards tr,\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards td{\r\n    display:block;\r\n    width:100%;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards{\r\n    border:0;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards thead{\r\n    position:absolute;\r\n    width:1px;\r\n    height:1px;\r\n    overflow:hidden;\r\n    clip:rect(0 0 0 0);\r\n    white-space:nowrap;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards tr{\r\n    margin-bottom:14px;\r\n    padding:7px 14px;\r\n    border:1px solid var(--tov-border);\r\n    border-radius:8px;\r\n    background:#fff;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards td{\r\n    display:grid;\r\n    grid-template-columns:minmax(112px,38%) 1fr;\r\n    gap:12px;\r\n    padding:10px 0;\r\n    border:0;\r\n    border-bottom:1px solid #e7edf2;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards td:last-child{\r\n    border-bottom:0;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards td::before{\r\n    content:attr(data-label);\r\n    color:#263b4f;\r\n    font-weight:700;\r\n  }\r\n}\r\n\r\n@media (max-width:480px){\r\n  #leeyee-spd-tov-withstand h2{\r\n    font-size:25px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand h3{\r\n    font-size:20px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-quick,\r\n  #leeyee-spd-tov-withstand .tov-toc,\r\n  #leeyee-spd-tov-withstand .tov-checklist,\r\n  #leeyee-spd-tov-withstand .tov-cta,\r\n  #leeyee-spd-tov-withstand .tov-example,\r\n  #leeyee-spd-tov-withstand .tov-evidence{\r\n    padding:19px 17px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-formula{\r\n    font-size:16px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-mobile-cards td{\r\n    grid-template-columns:1fr;\r\n    gap:3px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-steps li{\r\n    padding-left:48px;\r\n  }\r\n\r\n  #leeyee-spd-tov-withstand .tov-figure{\r\n    margin-top:24px;\r\n    margin-bottom:31px;\r\n  }\r\n}\r\n<\/style>\r\n\r\n<article id=\"leeyee-spd-tov-withstand\">\r\n  <div class=\"tov-reading\">\r\n\r\n    <p class=\"tov-intro\">\r\n      An SPD may survive a very high lightning impulse but fail during a much lower voltage that remains for seconds or longer. This longer abnormal voltage is called a <strong>temporary overvoltage, or TOV<\/strong>.\r\n    <\/p>\r\n\r\n    <p>\r\n      For OEM buyers and panel builders, TOV withstand is a procurement-risk parameter. It helps determine whether an SPD can remain stable, disconnect in a controlled manner or suffer serious damage when the system voltage rises beyond its intended continuous operating range.\r\n    <\/p>\r\n\r\n    <div class=\"tov-scope\">\r\n      <strong>Page scope:<\/strong> This guide focuses on SPD TOV withstand, Uc or Ucpv suitability and model-approval risk. For a detailed comparison of 275 V, 320 V, 385 V and 440 V ratings, use the separate <a href=\"https:\/\/www.cnspd.com\/spd-uc-selection-guide\/\">SPD Uc selection guide<\/a>. For visible failure diagnosis, see <a href=\"https:\/\/www.cnspd.com\/why-spd-burns-out\/\">why an SPD burns, melts or smokes<\/a>.\r\n    <\/div>\r\n\r\n    <section class=\"tov-quick\" aria-labelledby=\"tov-quick-answer\">\r\n      <span class=\"tov-eyebrow\">Quick answer<\/span>\r\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\/it\/spd-tov-withstand\/#what-is-spd-tov-withstand\" >What Is SPD TOV Withstand?<\/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\/it\/spd-tov-withstand\/#quick-approval-decision-for-buyers\" >Quick Approval Decision for Buyers<\/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\/it\/spd-tov-withstand\/#tov-and-surge-are-different-electrical-events\" >TOV and Surge Are Different Electrical Events<\/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\/it\/spd-tov-withstand\/#four-fields-are-needed-to-understand-a-tov-rating\" >Four Fields Are Needed to Understand a TOV Rating<\/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\/it\/spd-tov-withstand\/#uc-ucpv-and-ut-do-not-mean-the-same-thing\" >Uc, Ucpv and UT Do Not Mean the Same Thing<\/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\/it\/spd-tov-withstand\/#how-can-tov-make-an-spd-heat-disconnect-or-burn\" >How Can TOV Make an SPD Heat, Disconnect or Burn?<\/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\/it\/spd-tov-withstand\/#tov-must-be-checked-for-each-protection-mode\" >TOV Must Be Checked for Each Protection Mode<\/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\/it\/spd-tov-withstand\/#why-neutral-loss-is-a-critical-ac-tov-scenario\" >Why Neutral Loss Is a Critical AC TOV Scenario<\/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\/it\/spd-tov-withstand\/#how-to-read-a-real-tov-datasheet-entry\" >How to Read a Real TOV Datasheet Entry<\/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\/it\/spd-tov-withstand\/#do-ac-tov-conclusions-apply-directly-to-dc-or-pv-spds\" >Do AC TOV Conclusions Apply Directly to DC or PV SPDs?<\/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\/it\/spd-tov-withstand\/#spd-tov-verification-workflow-for-oem-approval\" >SPD TOV Verification Workflow for OEM Approval<\/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\/it\/spd-tov-withstand\/#confirm-tov-data-before-approving-the-spd-model\" >Confirm TOV Data Before Approving the SPD Model<\/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\/it\/spd-tov-withstand\/#what-should-be-checked-after-a-suspected-tov-event\" >What Should Be Checked After a Suspected TOV Event?<\/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\/it\/spd-tov-withstand\/#frequently-asked-questions-about-spd-tov-withstand\" >Frequently Asked Questions About SPD TOV Withstand<\/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\/it\/spd-tov-withstand\/#related-spd-selection-and-failure-guides\" >Related SPD Selection and Failure Guides<\/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\/it\/spd-tov-withstand\/#references\" >References<\/a><\/li><\/ul><\/nav><\/div>\n<h2 id=\"tov-quick-answer\"><span class=\"ez-toc-section\" id=\"what-is-spd-tov-withstand\"><\/span>What Is SPD TOV Withstand?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        A surge is a short transient event that an SPD is intended to limit. A TOV is an abnormal power-frequency or DC voltage that remains long enough to create sustained electrical and thermal stress.<sup><a href=\"#tov-ref-1\">[1]<\/a><\/sup><sup><a href=\"#tov-ref-2\">[2]<\/a><\/sup><sup><a href=\"#tov-ref-4\">[4]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <p>\r\n        TOV withstand is not one standalone voltage number. A meaningful declaration must identify the protection mode, applied voltage, duration and expected result.\r\n      <\/p>\r\n\r\n      <div class=\"tov-formula\">\r\n        TOV evidence = <span>mode<\/span> + <span>voltage<\/span> + <span>duration<\/span> + <span>result<\/span>\r\n      <\/div>\r\n\r\n      <ul class=\"tov-answer-grid\">\r\n        <li><strong>Uc or Ucpv covers continuous voltage.<\/strong> The real operating voltage must remain within the declared rating.<\/li>\r\n        <li><strong>UT describes a defined abnormal condition.<\/strong> It must be read together with duration and test outcome.<\/li>\r\n        <li><strong>Low Uc can increase TOV sensitivity.<\/strong> Sustained MOV conduction may cause heating and disconnection.<\/li>\r\n        <li><strong>High Imax does not prove TOV strength.<\/strong> Impulse-current and sustained-voltage risks are different.<\/li>\r\n      <\/ul>\r\n    <\/section>\r\n\r\n    <section aria-labelledby=\"tov-fast-decision\">\r\n      <h2 id=\"tov-fast-decision\"><span class=\"ez-toc-section\" id=\"quick-approval-decision-for-buyers\"><\/span>Quick Approval Decision for Buyers<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Use this table before approving a sample, BOM item or private-label model. It is a screening tool, not a substitute for project engineering.\r\n      <\/p>\r\n\r\n      <div class=\"tov-table-wrap\">\r\n        <table class=\"tov-mobile-cards tov-decision-table\">\r\n          <thead>\r\n            <tr>\r\n              <th style=\"width:17%;\">Decision<\/th>\r\n              <th style=\"width:42%;\">Finding<\/th>\r\n              <th style=\"width:41%;\">Required action<\/th>\r\n            <\/tr>\r\n          <\/thead>\r\n          <tbody>\r\n            <tr>\r\n              <td data-label=\"Decision\">Approve<\/td>\r\n              <td data-label=\"Finding\">The exact model data matches the system voltage, protection mode, TOV condition and short-circuit requirements.<\/td>\r\n              <td data-label=\"Required action\">Proceed to sample or BOM approval, subject to the complete project review.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Decision\">Hold<\/td>\r\n              <td data-label=\"Finding\">UT is shown without duration, the safe-failure result is unclear, or the certificate scope does not identify the exact model.<\/td>\r\n              <td data-label=\"Required action\">Request the missing test condition, report scope and installation information.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Decision\">Reject<\/td>\r\n              <td data-label=\"Finding\">The normal maximum voltage exceeds Uc or Ucpv, the application type is wrong, or the required protection mode is unsupported.<\/td>\r\n              <td data-label=\"Required action\">Select another model or correct the system specification before ordering.<\/td>\r\n            <\/tr>\r\n          <\/tbody>\r\n        <\/table>\r\n      <\/div>\r\n\r\n      <p class=\"tov-table-note\">\r\n        A product should not be approved from a front label, Imax value or general \u201cTOV resistant\u201d statement alone.\r\n      <\/p>\r\n    <\/section>\r\n\r\n    <figure class=\"tov-figure\">\r\n      <img fetchpriority=\"high\"\r\n        src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/07\/spd-tov-vs-surge-comparison.webp\"\r\n        alt=\"Comparison of transient surge and temporary overvoltage effects on a surge protective device\"\r\n        width=\"1448\"\r\n        height=\"1086\"\r\n        loading=\"eager\"\r\n        decoding=\"async\">\r\n      <figcaption>\r\n        A transient surge has a high but short peak. A TOV has a lower peak but remains long enough to stress the SPD continuously. Project-specific voltage and duration must still be confirmed.\r\n      <\/figcaption>\r\n    <\/figure>\r\n\r\n    <div class=\"tov-toc\">\r\n      <span class=\"tov-toc-title\">In this guide<\/span>\r\n      <ol>\r\n        <li><a href=\"#tov-versus-surge\">TOV versus surge<\/a><\/li>\r\n        <li><a href=\"#tov-rating-fields\">How to read a TOV rating<\/a><\/li>\r\n        <li><a href=\"#uc-and-tov\">Uc, Ucpv and UT<\/a><\/li>\r\n        <li><a href=\"#tov-failure-mechanism\">Why TOV damages an SPD<\/a><\/li>\r\n        <li><a href=\"#protection-mode-risk\">Protection-mode differences<\/a><\/li>\r\n        <li><a href=\"#ac-tov-risk\">AC distribution risks<\/a><\/li>\r\n        <li><a href=\"#datasheet-example\">Datasheet example<\/a><\/li>\r\n        <li><a href=\"#dc-pv-boundary\">DC and PV boundary<\/a><\/li>\r\n        <li><a href=\"#oem-verification\">OEM verification workflow<\/a><\/li>\r\n        <li><a href=\"#after-tov-event\">Checks after a TOV event<\/a><\/li>\r\n        <li><a href=\"#tov-faq\">Buyer FAQ<\/a><\/li>\r\n      <\/ol>\r\n    <\/div>\r\n\r\n    <section id=\"tov-versus-surge\">\r\n      <h2><span class=\"ez-toc-section\" id=\"tov-and-surge-are-different-electrical-events\"><\/span>TOV and Surge Are Different Electrical Events<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Both events raise voltage above its normal level. The important differences are duration, energy source and the way the SPD responds.\r\n      <\/p>\r\n\r\n      <div class=\"tov-table-wrap\">\r\n        <table class=\"tov-mobile-cards\">\r\n          <thead>\r\n            <tr>\r\n              <th style=\"width:21%;\">Comparison<\/th>\r\n              <th style=\"width:39.5%;\">Transient surge<\/th>\r\n              <th style=\"width:39.5%;\">Temporary overvoltage<\/th>\r\n            <\/tr>\r\n          <\/thead>\r\n          <tbody>\r\n            <tr>\r\n              <td data-label=\"Comparison\"><strong>Nature<\/strong><\/td>\r\n              <td data-label=\"Transient surge\">A short voltage or current impulse with a high peak.<\/td>\r\n              <td data-label=\"Temporary overvoltage\">An abnormal AC RMS or DC voltage that remains present.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Comparison\"><strong>Possible causes<\/strong><\/td>\r\n              <td data-label=\"Transient surge\">Lightning effects, switching and inductive load interruption.<\/td>\r\n              <td data-label=\"Temporary overvoltage\">Neutral loss, earth faults, poor regulation, wrong supply voltage or source faults.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Comparison\"><strong>SPD function<\/strong><\/td>\r\n              <td data-label=\"Transient surge\">Limits transient voltage and diverts impulse current.<\/td>\r\n              <td data-label=\"Temporary overvoltage\">Must remain stable or enter the declared controlled end-of-life condition.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Comparison\"><strong>Main ratings<\/strong><\/td>\r\n              <td data-label=\"Transient surge\">In, Imax, Iimp and Up.<\/td>\r\n              <td data-label=\"Temporary overvoltage\">Uc or Ucpv, UT, protection mode, duration and result.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Comparison\"><strong>Main risk<\/strong><\/td>\r\n              <td data-label=\"Transient surge\">Excessive impulse energy or accumulated surge stress.<\/td>\r\n              <td data-label=\"Temporary overvoltage\">Continuous conduction, heating, thermal runaway or fault-current follow-through.<\/td>\r\n            <\/tr>\r\n          <\/tbody>\r\n        <\/table>\r\n      <\/div>\r\n\r\n      <p class=\"tov-table-note\">\r\n        The applicable standard and product documentation determine the exact TOV test duration. Do not apply one universal time threshold to every system or SPD.\r\n      <\/p>\r\n\r\n      <div class=\"tov-warning\">\r\n        <strong>An SPD is not a voltage regulator.<\/strong>\r\n        It does not repair a broken neutral, correct a transformer tap, stabilise a generator or clear an earth fault. The system fault must be removed by the appropriate installation protection and control equipment.\r\n      <\/div>\r\n    <\/section>\r\n\r\n    <section id=\"tov-rating-fields\">\r\n      <h2><span class=\"ez-toc-section\" id=\"four-fields-are-needed-to-understand-a-tov-rating\"><\/span>Four Fields Are Needed to Understand a TOV Rating<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Statements such as \u201chigh TOV resistance\u201d or \u201cTOV-proof SPD\u201d are not complete engineering data. Buyers need four specific fields.\r\n      <\/p>\r\n\r\n      <div class=\"tov-table-wrap\">\r\n        <table class=\"tov-mobile-cards\">\r\n          <thead>\r\n            <tr>\r\n              <th style=\"width:23%;\">Required field<\/th>\r\n              <th style=\"width:37%;\">What it means<\/th>\r\n              <th style=\"width:40%;\">Procurement impact<\/th>\r\n            <\/tr>\r\n          <\/thead>\r\n          <tbody>\r\n            <tr>\r\n              <td data-label=\"Required field\"><strong>Protection mode<\/strong><\/td>\r\n              <td data-label=\"Meaning\">The two conductors across which the abnormal voltage is applied.<\/td>\r\n              <td data-label=\"Procurement impact\">L-N, L-PE and N-PE paths can experience different fault voltages.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Required field\"><strong>Applied voltage<\/strong><\/td>\r\n              <td data-label=\"Meaning\">The specified AC RMS or DC TOV test voltage, often identified as UT.<\/td>\r\n              <td data-label=\"Procurement impact\">Compare it with the credible abnormal voltage in the actual system.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Required field\"><strong>Duration<\/strong><\/td>\r\n              <td data-label=\"Meaning\">How long the abnormal voltage is applied during the stated condition.<\/td>\r\n              <td data-label=\"Procurement impact\">An SPD may withstand one voltage briefly but disconnect during a longer exposure.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Required field\"><strong>Result<\/strong><\/td>\r\n              <td data-label=\"Meaning\">The required behaviour after or during the test.<\/td>\r\n              <td data-label=\"Procurement impact\">Determine whether the SPD remains functional, disconnects or requires replacement.<\/td>\r\n            <\/tr>\r\n          <\/tbody>\r\n        <\/table>\r\n      <\/div>\r\n\r\n      <div class=\"tov-meaning\">\r\n        <strong>Buyer meaning<\/strong>\r\n        Do not compare two TOV claims unless the protection mode, voltage, duration and permitted result use equivalent conditions.\r\n      <\/div>\r\n    <\/section>\r\n\r\n    <section id=\"uc-and-tov\">\r\n      <h2><span class=\"ez-toc-section\" id=\"uc-ucpv-and-ut-do-not-mean-the-same-thing\"><\/span>Uc, Ucpv and UT Do Not Mean the Same Thing<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        <strong>Uc<\/strong> is the maximum continuous operating voltage that may be continuously applied to the stated SPD protection mode. <strong>Ucpv<\/strong> is the corresponding parameter used for photovoltaic SPDs.<sup><a href=\"#tov-ref-1\">[1]<\/a><\/sup><sup><a href=\"#tov-ref-2\">[2]<\/a><\/sup><sup><a href=\"#tov-ref-6\">[6]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <p>\r\n        <strong>UT<\/strong> describes behaviour during a specified temporary abnormal-voltage condition. Uc or Ucpv and UT are related, but one cannot replace the other.\r\n      <\/p>\r\n\r\n      <div class=\"tov-table-wrap\">\r\n        <table class=\"tov-mobile-cards\">\r\n          <thead>\r\n            <tr>\r\n              <th style=\"width:20%;\">Parameter<\/th>\r\n              <th style=\"width:38%;\">Question answered<\/th>\r\n              <th style=\"width:42%;\">Approval risk<\/th>\r\n            <\/tr>\r\n          <\/thead>\r\n          <tbody>\r\n            <tr>\r\n              <td data-label=\"Parameter\"><strong>Un or Uo<\/strong><\/td>\r\n              <td data-label=\"Question answered\">What is the nominal system or phase-to-neutral voltage?<\/td>\r\n              <td data-label=\"Approval risk\">It is a starting point, not the final SPD voltage-selection value.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Parameter\"><strong>Uc<\/strong><\/td>\r\n              <td data-label=\"Question answered\">Can the SPD remain connected continuously at this voltage?<\/td>\r\n              <td data-label=\"Approval risk\">A value that is too low can increase leakage, heating and early disconnection.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Parameter\"><strong>Ucpv<\/strong><\/td>\r\n              <td data-label=\"Question answered\">Can the PV SPD remain connected at the calculated maximum array voltage?<\/td>\r\n              <td data-label=\"Approval risk\">Normal inverter operating voltage alone is not enough.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Parameter\"><strong>UT<\/strong><\/td>\r\n              <td data-label=\"Question answered\">What happens under the stated abnormal voltage and duration?<\/td>\r\n              <td data-label=\"Approval risk\">A voltage value without duration and result is incomplete.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Parameter\"><strong>Up<\/strong><\/td>\r\n              <td data-label=\"Question answered\">What voltage protection level is declared during the specified surge test?<\/td>\r\n              <td data-label=\"Approval risk\">A higher Uc does not automatically provide the most suitable protection coordination.<\/td>\r\n            <\/tr>\r\n          <\/tbody>\r\n        <\/table>\r\n      <\/div>\r\n\r\n      <h3>Why Can a Low Uc Cause Failure?<\/h3>\r\n\r\n      <p>\r\n        Most voltage-limiting AC power SPDs use one or more metal-oxide varistors. Under normal voltage, an MOV carries only a small leakage current.\r\n      <\/p>\r\n\r\n      <p>\r\n        When the applied voltage rises beyond the component\u2019s stable operating range, MOV current can increase sharply. If the abnormal voltage remains, electrical energy is converted into heat rather than being handled as one short surge impulse.<sup><a href=\"#tov-ref-9\">[9]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <h3>Is a Higher Uc Always Better?<\/h3>\r\n\r\n      <p>\r\n        No. A higher Uc can increase continuous-voltage margin, but the selected SPD must still provide a suitable Up, protection mode and coordination with the equipment being protected.\r\n      <\/p>\r\n\r\n      <p>\r\n        The correct choice is not simply the highest available Uc. It is a rating that safely covers the real maximum operating voltage and credible fault conditions while meeting the required protection level.<sup><a href=\"#tov-ref-3\">[3]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <div class=\"tov-danger\">\r\n        <strong>Do not use Imax as a substitute for Uc or TOV data.<\/strong>\r\n        A larger impulse-current rating does not prove that an SPD can tolerate neutral loss, sustained overvoltage or an incorrect supply voltage.\r\n      <\/div>\r\n    <\/section>\r\n\r\n    <section id=\"tov-failure-mechanism\">\r\n      <h2><span class=\"ez-toc-section\" id=\"how-can-tov-make-an-spd-heat-disconnect-or-burn\"><\/span>How Can TOV Make an SPD Heat, Disconnect or Burn?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        The exact response depends on SPD technology, internal construction and the system fault. A common MOV-based failure sequence is shown below.\r\n      <\/p>\r\n\r\n      <figure class=\"tov-figure\">\r\n        <img loading=\"lazy\"\r\n          src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/07\/spd-tov-failure-mechanism.webp\"\r\n          alt=\"SPD temporary overvoltage failure mechanism from voltage above Uc to thermal disconnection or damage\"\r\n          width=\"1448\"\r\n          height=\"1086\"\r\n          loading=\"lazy\"\r\n          decoding=\"async\">\r\n        <figcaption>\r\n          A typical MOV-based TOV failure path. The final result depends on voltage, duration, internal disconnection, available fault current and backup-protection coordination.\r\n        <\/figcaption>\r\n      <\/figure>\r\n\r\n      <ol class=\"tov-steps\">\r\n        <li>\r\n          <strong>The applied voltage exceeds the suitable continuous range.<\/strong>\r\n          This may result from a low Uc selection or an abnormal system condition.\r\n        <\/li>\r\n        <li>\r\n          <strong>The voltage-limiting component conducts continuously.<\/strong>\r\n          The SPD is drawing power-frequency or DC current instead of handling one short impulse.\r\n        <\/li>\r\n        <li>\r\n          <strong>Internal temperature rises.<\/strong>\r\n          Continued energy input reduces the remaining thermal margin.\r\n        <\/li>\r\n        <li>\r\n          <strong>The thermal disconnector may open.<\/strong>\r\n          A controlled disconnection can isolate the stressed component and change the status indicator.\r\n        <\/li>\r\n        <li>\r\n          <strong>Severe damage remains possible.<\/strong>\r\n          A severe TOV, high available fault current or inadequate disconnection can enlarge the failure.\r\n        <\/li>\r\n      <\/ol>\r\n\r\n      <p>\r\n        NIST-hosted TOV research found that SPD responses under sustained abnormal voltage can range from no damage to complete destruction. The paper identifies maximum continuous operating voltage and disconnector response as important factors in TOV susceptibility.<sup><a href=\"#tov-ref-9\">[9]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <div class=\"tov-danger\">\r\n        <strong>A red indicator does not prove that lightning caused the failure.<\/strong>\r\n        Repeated surges, TOV, incorrect Uc, high temperature, wiring errors and short-circuit conditions can all lead to end of life.\r\n      <\/div>\r\n    <\/section>\r\n\r\n    <section id=\"protection-mode-risk\">\r\n      <h2><span class=\"ez-toc-section\" id=\"tov-must-be-checked-for-each-protection-mode\"><\/span>TOV Must Be Checked for Each Protection Mode<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        A multipole SPD is not exposed to one single voltage. Each protection element sees the voltage between the two conductors connected to that protection path.\r\n      <\/p>\r\n\r\n      <div class=\"tov-table-wrap\">\r\n        <table class=\"tov-mobile-cards\">\r\n          <thead>\r\n            <tr>\r\n              <th style=\"width:21%;\">Protection mode<\/th>\r\n              <th style=\"width:39%;\">Normal selection question<\/th>\r\n              <th style=\"width:40%;\">TOV risk to confirm<\/th>\r\n            <\/tr>\r\n          <\/thead>\r\n          <tbody>\r\n            <tr>\r\n              <td data-label=\"Protection mode\"><strong>L-N<\/strong><\/td>\r\n              <td data-label=\"Normal question\">What is the maximum continuous phase-to-neutral voltage?<\/td>\r\n              <td data-label=\"TOV risk\">Neutral loss, poor neutral connection and load imbalance.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Protection mode\"><strong>L-PE<\/strong><\/td>\r\n              <td data-label=\"Normal question\">What voltage can appear between the phase conductor and earth?<\/td>\r\n              <td data-label=\"TOV risk\">Earth faults, neutral displacement and earthing-system behaviour.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Protection mode\"><strong>N-PE<\/strong><\/td>\r\n              <td data-label=\"Normal question\">Which N-PE protection technology and rating are used?<\/td>\r\n              <td data-label=\"TOV risk\">Temporary neutral-to-earth voltage during certain earth-fault conditions.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Protection mode\"><strong>DC +\/\u2212<\/strong><\/td>\r\n              <td data-label=\"Normal question\">What is the maximum pole-to-pole DC voltage?<\/td>\r\n              <td data-label=\"TOV risk\">Charging voltage, regulation faults and incorrect circuit configuration.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Protection mode\"><strong>DC pole-PE<\/strong><\/td>\r\n              <td data-label=\"Normal question\">How is the DC system referenced to earth?<\/td>\r\n              <td data-label=\"TOV risk\">An earth fault can shift the voltage across a pole-to-earth protection path.<\/td>\r\n            <\/tr>\r\n          <\/tbody>\r\n        <\/table>\r\n      <\/div>\r\n\r\n      <div class=\"tov-meaning\">\r\n        <strong>Engineering meaning<\/strong>\r\n        \u201cSuitable for a 230\/400 V system\u201d is not a complete model confirmation. The expected voltage across every connected protection mode must be identified.\r\n      <\/div>\r\n    <\/section>\r\n\r\n    <section id=\"ac-tov-risk\">\r\n      <h2><span class=\"ez-toc-section\" id=\"why-neutral-loss-is-a-critical-ac-tov-scenario\"><\/span>Why Neutral Loss Is a Critical AC TOV Scenario<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        In a healthy 230\/400 V three-phase four-wire system, an L-N protection path normally sees approximately 230 V.\r\n      <\/p>\r\n\r\n      <p>\r\n        If the neutral conductor opens or develops high impedance, the neutral point is no longer stable. With unbalanced single-phase loads, some L-N voltages can fall while another rises substantially and may approach the 400 V line-to-line voltage.<sup><a href=\"#tov-ref-4\">[4]<\/a><\/sup><sup><a href=\"#tov-ref-9\">[9]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <div class=\"tov-example\">\r\n        <span class=\"tov-example-label\">Simplified engineering scenario<\/span>\r\n        <h3>Healthy Supply Versus Neutral-Loss Condition<\/h3>\r\n\r\n        <p>\r\n          A 275 V Uc SPD may be suitable for a stable 230 V L-N circuit when the complete system and product requirements are satisfied.\r\n        <\/p>\r\n\r\n        <p>\r\n          If neutral loss causes the same protection path to experience a much higher sustained voltage, the SPD may begin conducting continuously. Whether it withstands, disconnects safely or suffers damage must be confirmed from the exact model\u2019s TOV data.\r\n        <\/p>\r\n\r\n        <p>\r\n          This example does not prove that every neutral-loss event produces exactly 400 V. The actual voltage depends on the connected loads, network arrangement and fault condition.\r\n        <\/p>\r\n      <\/div>\r\n\r\n      <div class=\"tov-meaning\">\r\n        <strong>Panel-builder meaning<\/strong>\r\n        Do not approve an L-N module only because the drawing states \u201c230\/400 V.\u201d Confirm normal maximum voltage, neutral-loss risk, protection mode and the declared TOV result.\r\n      <\/div>\r\n\r\n      <h3>Earth Faults and Earthing Arrangement<\/h3>\r\n\r\n      <p>\r\n        TN-S, TN-C-S, TT and IT systems can place different temporary voltages across L-N, L-PE and N-PE protection paths. The actual stress depends on the installation arrangement and fault condition.<sup><a href=\"#tov-ref-3\">[3]<\/a><\/sup><sup><a href=\"#tov-ref-4\">[4]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <p>\r\n        This is especially important when comparing 4+0 and 3+1 circuits. The L-N modules and the N-PE element perform different functions and should not be assumed to have identical TOV behaviour.\r\n      <\/p>\r\n\r\n      <h3>Generators, Transformers and Unstable Grids<\/h3>\r\n\r\n      <p>\r\n        Generator regulation faults, transformer-tap errors, load rejection, ferroresonance and poor utility regulation can create sustained abnormal voltage.\r\n      <\/p>\r\n\r\n      <p>\r\n        For these projects, request measured voltage records or the design voltage tolerance. Nominal voltage alone is not sufficient for final Uc approval.\r\n      <\/p>\r\n\r\n      <p>\r\n        Installation-level requirements and system-specific TOV conditions should be checked against the applicable edition of IEC 60364 and the local electrical code. The related <a href=\"https:\/\/www.cnspd.com\/iec-60364-5-534-spd-installation\/\">IEC 60364-5-534 SPD installation guide<\/a> explains the wider installation checks.\r\n      <\/p>\r\n    <\/section>\r\n\r\n    <section id=\"datasheet-example\">\r\n      <h2><span class=\"ez-toc-section\" id=\"how-to-read-a-real-tov-datasheet-entry\"><\/span>How to Read a Real TOV Datasheet Entry<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        The following example uses values published in a third-party manufacturer\u2019s technical guide. It explains the reading method only. It is not a recommendation for a LEEYEE model and must not be transferred to another product without verification.<sup><a href=\"#tov-ref-10\">[10]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <div class=\"tov-table-wrap\">\r\n        <table class=\"tov-mobile-cards\">\r\n          <thead>\r\n            <tr>\r\n              <th style=\"width:25%;\">Published entry<\/th>\r\n              <th style=\"width:37%;\">Correct interpretation<\/th>\r\n              <th style=\"width:38%;\">Wrong assumption to avoid<\/th>\r\n            <\/tr>\r\n          <\/thead>\r\n          <tbody>\r\n            <tr>\r\n              <td data-label=\"Published entry\"><strong>Uc 275 V<\/strong><\/td>\r\n              <td data-label=\"Correct interpretation\">The declared maximum continuous operating voltage for the stated protection mode.<\/td>\r\n              <td data-label=\"Wrong assumption\">The product can operate continuously at every voltage below its highest UT value.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Published entry\"><strong>UT 337 V \/ 5 s<\/strong><\/td>\r\n              <td data-label=\"Correct interpretation\">A short-duration TOV condition with the outcome stated in the same product documentation.<\/td>\r\n              <td data-label=\"Wrong assumption\">337 V is another continuous operating-voltage rating.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Published entry\"><strong>UT 442 V \/ 120 min<\/strong><\/td>\r\n              <td data-label=\"Correct interpretation\">A longer-duration condition associated with a declared safe-failure result.<\/td>\r\n              <td data-label=\"Wrong assumption\">The SPD continues protecting normally for two hours at 442 V.<\/td>\r\n            <\/tr>\r\n            <tr>\r\n              <td data-label=\"Published entry\"><strong>Separate N-PE value<\/strong><\/td>\r\n              <td data-label=\"Correct interpretation\">A TOV condition specifically stated for the N-PE protection element.<\/td>\r\n              <td data-label=\"Wrong assumption\">The same value automatically applies to L-N and L-PE elements.<\/td>\r\n            <\/tr>\r\n          <\/tbody>\r\n        <\/table>\r\n      <\/div>\r\n\r\n      <div class=\"tov-danger\">\r\n        <strong>Safe failure does not mean continued surge protection.<\/strong>\r\n        A safely disconnected module may no longer protect downstream equipment. Its visual indicator or remote contact must trigger inspection and, where required, replacement.\r\n      <\/div>\r\n\r\n      <h3>What Should Be Verified on a LEEYEE Model?<\/h3>\r\n\r\n      <p>\r\n        Do not assume that a third-party example represents a LEEYEE product. Request the exact LEEYEE model datasheet, connection diagram and applicable test or certificate scope for project confirmation.\r\n      <\/p>\r\n\r\n      <div class=\"tov-evidence\">\r\n        <h3>Model-Specific Evidence to Request<\/h3>\r\n        <ul class=\"tov-evidence-list\">\r\n          <li>Exact product and cartridge label<\/li>\r\n          <li>Uc or Ucpv for the stated protection mode<\/li>\r\n          <li>UT voltage, duration and declared result<\/li>\r\n          <li>Visual status-window operation<\/li>\r\n          <li>Remote signalling contact information<\/li>\r\n          <li>Internal and external disconnection requirements<\/li>\r\n          <li>Isccr or ISCPV rating where applicable<\/li>\r\n          <li>Backup fuse or MCB requirements<\/li>\r\n          <li>Installation and wiring instructions<\/li>\r\n          <li>Model-specific report or certificate scope<\/li>\r\n          <li>OEM label and packaging approval drawing<\/li>\r\n          <li>Sample inspection and approval record<\/li>\r\n        <\/ul>\r\n      <\/div>\r\n\r\n      <p>\r\n        Evidence should be reviewed at exact-model level. A certificate, report or datasheet for one voltage version or pole configuration must not be assumed to cover another.\r\n      <\/p>\r\n    <\/section>\r\n\r\n    <section id=\"dc-pv-boundary\">\r\n      <h2><span class=\"ez-toc-section\" id=\"do-ac-tov-conclusions-apply-directly-to-dc-or-pv-spds\"><\/span>Do AC TOV Conclusions Apply Directly to DC or PV SPDs?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        No. General DC and solar PV circuits require separate voltage calculations, protection modes and product standards.\r\n      <\/p>\r\n\r\n      <p>\r\n        IEC 61643-41:2025 covers SPDs connected to general DC low-voltage power circuits. PV SPDs remain within IEC 61643-31, with selection principles addressed by IEC 61643-32.<sup><a href=\"#tov-ref-5\">[5]<\/a><\/sup><sup><a href=\"#tov-ref-6\">[6]<\/a><\/sup><sup><a href=\"#tov-ref-7\">[7]<\/a><\/sup>\r\n      <\/p>\r\n\r\n      <div class=\"tov-warning\">\r\n        <strong>A \u201c1000 V DC SPD\u201d label is not a complete PV approval basis.<\/strong>\r\n        Confirm Ucpv, maximum corrected string open-circuit voltage, protection configuration, PV short-circuit rating, disconnection behaviour and certificate scope.\r\n      <\/div>\r\n\r\n      <p>\r\n        Use the separate <a href=\"https:\/\/www.cnspd.com\/dc-spd-ucpv-selection\/\">DC and PV SPD Ucpv selection guide<\/a> for the complete PV voltage-selection process.\r\n      <\/p>\r\n    <\/section>\r\n\r\n    <section id=\"oem-verification\">\r\n      <h2><span class=\"ez-toc-section\" id=\"spd-tov-verification-workflow-for-oem-approval\"><\/span>SPD TOV Verification Workflow for OEM Approval<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Confirm the electrical system before approving the SPD. The workflow below keeps system data, product ratings and approval documents connected.\r\n      <\/p>\r\n\r\n      <figure class=\"tov-figure\">\r\n        <img loading=\"lazy\"\r\n          src=\"https:\/\/www.cnspd.com\/wp-content\/uploads\/2026\/07\/spd-tov-oem-verification-workflow.webp\"\r\n          alt=\"OEM workflow for verifying SPD Uc Ucpv protection mode and temporary overvoltage withstand\"\r\n          width=\"1448\"\r\n          height=\"1086\"\r\n          loading=\"lazy\"\r\n          decoding=\"async\">\r\n        <figcaption>\r\n          A practical TOV verification sequence for sample, BOM and OEM approval. The final decision must use the exact system configuration and exact SPD model documentation.\r\n        <\/figcaption>\r\n      <\/figure>\r\n\r\n      <ol class=\"tov-steps\">\r\n        <li>\r\n          <strong>Identify the circuit.<\/strong>\r\n          Separate AC mains, general DC and solar PV applications. Similar housings do not make the products interchangeable.\r\n        <\/li>\r\n        <li>\r\n          <strong>Confirm the real maximum operating voltage.<\/strong>\r\n          Include supply tolerance, generator or transformer behaviour, charging voltage or PV cold-temperature voltage.\r\n        <\/li>\r\n        <li>\r\n          <strong>Confirm the earthing arrangement.<\/strong>\r\n          Record TN-S, TN-C-S, TT, IT or the relevant DC grounding method.\r\n        <\/li>\r\n        <li>\r\n          <strong>Map every protection mode.<\/strong>\r\n          Check L-N, L-PE, N-PE, pole-to-pole and pole-to-earth paths as applicable.\r\n        <\/li>\r\n        <li>\r\n          <strong>Define credible TOV events.<\/strong>\r\n          Review neutral loss, earth faults, regulation faults and source-specific abnormal conditions.\r\n        <\/li>\r\n        <li>\r\n          <strong>Compare the complete SPD data.<\/strong>\r\n          Review Uc or Ucpv, UT, duration, result, Up, short-circuit rating and disconnection arrangement.\r\n        <\/li>\r\n        <li>\r\n          <strong>Verify approval-document scope.<\/strong>\r\n          Confirm that the datasheet, report and certificate apply to the exact voltage version, pole configuration and model ordered.\r\n        <\/li>\r\n      <\/ol>\r\n\r\n      <div class=\"tov-checklist\">\r\n        <h3>Information to Send Before Requesting a Model Recommendation<\/h3>\r\n        <ul class=\"tov-check-grid\">\r\n          <li>Nominal system voltage<\/li>\r\n          <li>Maximum continuous voltage<\/li>\r\n          <li>AC, general DC or PV application<\/li>\r\n          <li>System frequency where applicable<\/li>\r\n          <li>Earthing or grounding arrangement<\/li>\r\n          <li>Required protection modes<\/li>\r\n          <li>Neutral-loss or earth-fault scenario<\/li>\r\n          <li>Uc or Ucpv under consideration<\/li>\r\n          <li>Required TOV voltage and duration<\/li>\r\n          <li>Required withstand or safe-failure result<\/li>\r\n          <li>Prospective short-circuit current<\/li>\r\n          <li>Backup fuse or MCB information<\/li>\r\n          <li>Required standard or certificate<\/li>\r\n          <li>Remote signalling requirement<\/li>\r\n          <li>Quantity and installation position<\/li>\r\n          <li>OEM label or packaging requirement<\/li>\r\n        <\/ul>\r\n      <\/div>\r\n\r\n      <div class=\"tov-cta\">\r\n        <h2><span class=\"ez-toc-section\" id=\"confirm-tov-data-before-approving-the-spd-model\"><\/span>Confirm TOV Data Before Approving the SPD Model<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n        <p>\r\n          Send the system voltage, earthing arrangement, protection modes and credible abnormal-voltage conditions. LEEYEE can help identify which Uc, Ucpv and TOV data should be verified before sample or BOM approval.\r\n        <\/p>\r\n        <p>\r\n          CNSPD is LEEYEE\u2019s surge protection-focused platform for global technical buyers. <strong>Built to Protect. Trusted to Last.<\/strong>\r\n        <\/p>\r\n        <a href=\"javascript:void(0);\" class=\"leeyee-site-popup-btn\"><span>Share Your System Details for Review<\/span><\/a>\r\n      <\/div>\r\n    <\/section>\r\n\r\n    <section id=\"after-tov-event\">\r\n      <h2><span class=\"ez-toc-section\" id=\"what-should-be-checked-after-a-suspected-tov-event\"><\/span>What Should Be Checked After a Suspected TOV Event?<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <p>\r\n        Do not install a replacement cartridge before identifying the original abnormal voltage. A new SPD may fail again if the system fault remains.\r\n      <\/p>\r\n\r\n      <ol>\r\n        <li>Isolate the circuit according to the site\u2019s electrical-safety procedure.<\/li>\r\n        <li>Record the SPD indicator, remote alarm and complete product label.<\/li>\r\n        <li>Measure L-N, L-L, L-PE, N-PE or DC pole voltages as applicable.<\/li>\r\n        <li>Check neutral continuity, earthing and the current single-line diagram.<\/li>\r\n        <li>Inspect the cartridge, base, conductors, terminals and backup protection.<\/li>\r\n        <li>Review generator, transformer, inverter, relay and utility-event records.<\/li>\r\n        <li>Confirm the replacement Uc, Ucpv, TOV data and protection configuration.<\/li>\r\n      <\/ol>\r\n\r\n      <div class=\"tov-meaning\">\r\n        <strong>Root-cause rule<\/strong>\r\n        Treat TOV-damaged surge protection as evidence of a system abnormality, not merely as a consumable module that needs routine replacement.\r\n      <\/div>\r\n\r\n      <p>\r\n        For a wider diagnostic process, use the related <a href=\"https:\/\/www.cnspd.com\/spd-failure-causes\/\">SPD failure causes guide<\/a>.\r\n      <\/p>\r\n    <\/section>\r\n\r\n    <section id=\"tov-faq\">\r\n      <h2><span class=\"ez-toc-section\" id=\"frequently-asked-questions-about-spd-tov-withstand\"><\/span>Frequently Asked Questions About SPD TOV Withstand<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n\r\n      <div class=\"tov-faq\">\r\n        <div class=\"tov-faq-item\">\r\n          <h3>Can an SPD protect equipment against a temporary overvoltage?<\/h3>\r\n          <p>\r\n            An SPD is primarily intended to limit transient overvoltages. It does not normally regulate or remove a sustained abnormal system voltage. During a TOV, it may remain stable or enter its declared controlled end-of-life condition.\r\n          <\/p>\r\n        <\/div>\r\n\r\n        <div class=\"tov-faq-item\">\r\n          <h3>Can TOV make an SPD burn?<\/h3>\r\n          <p>\r\n            Yes. Sustained conduction can cause heating, thermal runaway, disconnection or severe damage. The result depends on voltage, duration, SPD design, available fault current and protective-device coordination.\r\n          <\/p>\r\n        <\/div>\r\n\r\n        <div class=\"tov-faq-item\">\r\n          <h3>Does a larger Imax improve TOV withstand?<\/h3>\r\n          <p>\r\n            Not necessarily. Imax is an impulse-current parameter. TOV suitability depends on continuous operating voltage, protection mode, defined TOV behaviour and disconnection design.\r\n          <\/p>\r\n        <\/div>\r\n\r\n        <div class=\"tov-faq-item\">\r\n          <h3>Does a higher Uc prevent every TOV failure?<\/h3>\r\n          <p>\r\n            No. A higher Uc can increase continuous-voltage margin, but duration, protection mode, SPD technology and disconnection behaviour still affect the result.\r\n          <\/p>\r\n        <\/div>\r\n\r\n        <div class=\"tov-faq-item\">\r\n          <h3>Can neutral loss damage a 275 V or 320 V SPD?<\/h3>\r\n          <p>\r\n            It can. Neutral displacement in a three-phase four-wire system can raise the voltage across an L-N protection path well above normal. The outcome depends on the actual voltage, duration and model-specific TOV behaviour.\r\n          <\/p>\r\n        <\/div>\r\n\r\n        <div class=\"tov-faq-item\">\r\n          <h3>What does safe failure mean?<\/h3>\r\n          <p>\r\n            It means that controlled disconnection or end of life may be permitted under the stated test condition. It does not mean that the module continues to provide surge protection.\r\n          <\/p>\r\n        <\/div>\r\n\r\n        <div class=\"tov-faq-item\">\r\n          <h3>Is Ucpv the same as a PV system\u2019s nominal voltage?<\/h3>\r\n          <p>\r\n            No. Ucpv is the maximum continuous operating voltage declared for the PV SPD. It must be checked against the maximum voltage calculated for the actual PV array and protection configuration.\r\n          <\/p>\r\n        <\/div>\r\n\r\n        <div class=\"tov-faq-item\">\r\n          <h3>Which TOV documents should an OEM buyer request?<\/h3>\r\n          <p>\r\n            Request the exact-model datasheet, protection-mode diagram, Uc or Ucpv, UT voltage, duration, result definition, short-circuit rating, backup-protection requirements, installation instructions and certificate scope.\r\n          <\/p>\r\n        <\/div>\r\n      <\/div>\r\n    <\/section>\r\n\r\n    <section class=\"tov-related\">\r\n      <h2><span class=\"ez-toc-section\" id=\"related-spd-selection-and-failure-guides\"><\/span>Related SPD Selection and Failure Guides<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n      <ul>\r\n        <li><a href=\"https:\/\/www.cnspd.com\/spd-uc-selection-guide\/\">SPD Uc Selection Guide: 275 V, 320 V, 385 V or 440 V<\/a><\/li>\r\n        <li><a href=\"https:\/\/www.cnspd.com\/dc-spd-ucpv-selection\/\">DC and PV SPD Ucpv Selection Guide<\/a><\/li>\r\n        <li><a href=\"https:\/\/www.cnspd.com\/spd-failure-causes\/\">Common Causes of SPD Failure<\/a><\/li>\r\n        <li><a href=\"https:\/\/www.cnspd.com\/why-spd-burns-out\/\">Why Does an SPD Burn, Melt or Smoke?<\/a><\/li>\r\n        <li><a href=\"https:\/\/www.cnspd.com\/iec-60364-5-534-spd-installation\/\">IEC 60364-5-534 SPD Installation Guide<\/a><\/li>\r\n      <\/ul>\r\n    <\/section>\r\n\r\n    <section class=\"tov-references\" aria-labelledby=\"tov-reference-title\">\r\n      <h2 id=\"tov-reference-title\"><span class=\"ez-toc-section\" id=\"references\"><\/span>References<span class=\"ez-toc-section-end\"><\/span><\/h2>\r\n      <ol>\r\n        <li id=\"tov-ref-1\">\r\n          International Electrotechnical Commission, <em>IEC 61643-01:2024 \u2014 Low-voltage surge protective devices \u2014 Part 01: General requirements and test methods<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/65315\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-2\">\r\n          International Electrotechnical Commission, <em>IEC 61643-11:2025 \u2014 Low-voltage surge protective devices \u2014 Part 11: Surge protective devices connected to AC low-voltage power systems \u2014 Requirements and test methods<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/65314\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-3\">\r\n          International Electrotechnical Commission, <em>IEC 61643-12:2020 \u2014 Low-voltage surge protective devices \u2014 Part 12: Surge protective devices connected to low-voltage power systems \u2014 Selection and application principles<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/32531\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-4\">\r\n          International Electrotechnical Commission, <em>IEC 60364-4-44:2024 \u2014 Low-voltage electrical installations \u2014 Part 4-44: Protection for safety \u2014 Protection against voltage disturbances and electromagnetic disturbances<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/73668\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-5\">\r\n          International Electrotechnical Commission, <em>IEC 61643-41:2025 \u2014 Low-voltage surge protective devices \u2014 Part 41: Surge protective devices connected to DC low-voltage power systems \u2014 Requirements and test methods<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/27917\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-6\">\r\n          International Electrotechnical Commission, <em>IEC 61643-31:2018 and Corrigendum 1:2022 \u2014 Requirements and test methods for SPDs for photovoltaic installations<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/26931\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-7\">\r\n          International Electrotechnical Commission, <em>IEC 61643-32:2017 and Corrigendum 1:2019 \u2014 Surge protective devices connected to the DC side of photovoltaic installations \u2014 Selection and application principles<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/30774\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-8\">\r\n          International Electrotechnical Commission, <em>IEC 60364-7-712:2025 \u2014 Low-voltage electrical installations \u2014 Solar photovoltaic power-supply installations<\/em>.\r\n          <a href=\"https:\/\/webstore.iec.ch\/en\/publication\/65748\" target=\"_blank\" rel=\"noopener\">Official IEC publication page<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-9\">\r\n          D. Kladar, F. Martzloff and D. Nastasi, <em>TOV Effects on Surge-Protective Devices<\/em>, Eaton Electrical and EPRI Solutions, hosted by the U.S. National Institute of Standards and Technology.\r\n          <a href=\"https:\/\/www.nist.gov\/document\/tovsonspdspdf\" target=\"_blank\" rel=\"noopener\">NIST-hosted technical paper<\/a>.\r\n        <\/li>\r\n        <li id=\"tov-ref-10\">\r\n          ABB Furse, <em>ESP Type 1 and Type 2 Surge Protection Series Product Guide<\/em>, including model-specific Uc, UT, withstand and safe-failure data.\r\n          <a href=\"https:\/\/library.e.abb.com\/public\/e365a493461041e48f8a0f487f885197\/Furse_ESP_T1_T2_Surge_Protection_Series_Product_Guide_211021.pdf\" target=\"_blank\" rel=\"noopener\">Official ABB technical guide<\/a>.\r\n        <\/li>\r\n      <\/ol>\r\n    <\/section>\r\n\r\n  <\/div>\r\n<\/article>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>An SPD may survive a very high lightning impulse but fail during a much lower voltage that remains for seconds or longer. This longer abnormal voltage is called a temporary overvoltage, or TOV. For OEM buyers and panel builders, TOV withstand is a procurement-risk parameter. It helps determine whether an SPD can remain stable, disconnect&#8230;<\/p>","protected":false},"author":18,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,488,422],"tags":[],"class_list":["post-30391","post","type-post","status-publish","format-standard","hentry","category-news","category-surge-protection","category-industry-news"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.0 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>SPD TOV Withstand: Uc, UT &amp; Safe-Failure Guide<\/title>\n<meta name=\"description\" content=\"Learn how temporary overvoltage affects SPDs, why low Uc can cause heating, and what OEM buyers must verify before approving an SPD model.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.cnspd.com\/it\/spd-tov-withstand\/\" \/>\n<meta property=\"og:locale\" content=\"it_IT\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"SPD TOV Withstand: Uc, UT &amp; Safe-Failure Guide\" \/>\n<meta property=\"og:description\" content=\"Learn how temporary overvoltage affects SPDs, why low Uc can cause heating, and what OEM buyers must verify before approving an SPD model.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.cnspd.com\/it\/spd-tov-withstand\/\" \/>\n<meta property=\"og:site_name\" content=\"Surge Protector, Surge Arrestor, Isolating Switch - LEEYEE\" \/>\n<meta property=\"article:published_time\" content=\"2026-07-24T04:49:49+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-07-24T06:43:52+00:00\" \/>\n<meta name=\"author\" content=\"Devin Ling\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Scritto da\" \/>\n\t<meta name=\"twitter:data1\" content=\"Devin Ling\" \/>\n\t<meta name=\"twitter:label2\" content=\"Tempo di lettura stimato\" \/>\n\t<meta name=\"twitter:data2\" content=\"15 minuti\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/\"},\"author\":{\"name\":\"Devin Ling\",\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/#\\\/schema\\\/person\\\/f49dbafe62c5b47100ad2d9f88af92d3\"},\"headline\":\"SPD TOV Withstand Guide for OEM Buyers and Panel Builders\",\"datePublished\":\"2026-07-24T04:49:49+00:00\",\"dateModified\":\"2026-07-24T06:43:52+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/\"},\"wordCount\":3241,\"articleSection\":[\"News\",\"Surge Protection\",\"Technical Guides\"],\"inLanguage\":\"it-IT\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/\",\"url\":\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/\",\"name\":\"SPD TOV Withstand: Uc, UT & Safe-Failure Guide\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/#website\"},\"datePublished\":\"2026-07-24T04:49:49+00:00\",\"dateModified\":\"2026-07-24T06:43:52+00:00\",\"author\":{\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/#\\\/schema\\\/person\\\/f49dbafe62c5b47100ad2d9f88af92d3\"},\"description\":\"Learn how temporary overvoltage affects SPDs, why low Uc can cause heating, and what OEM buyers must verify before approving an SPD model.\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/#breadcrumb\"},\"inLanguage\":\"it-IT\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/spd-tov-withstand\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/www.cnspd.com\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"SPD TOV Withstand Guide for OEM Buyers and Panel Builders\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/www.cnspd.com\\\/#website\",\"url\":\"https:\\\/\\\/www.cnspd.com\\\/\",\"name\":\"Surge Protector, Surge Arrestor, Isolating Switch - 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