{"id":19987,"date":"2025-11-21T01:54:00","date_gmt":"2025-11-20T17:54:00","guid":{"rendered":"https:\/\/viox.com\/?p=19987"},"modified":"2025-11-14T14:54:42","modified_gmt":"2025-11-14T06:54:42","slug":"what-is-breaker-selectivity-coordination-guide","status":"publish","type":"post","link":"https:\/\/test.viox.com\/my\/what-is-breaker-selectivity-coordination-guide\/","title":{"rendered":"What is \u201cSelectivity\u201d? A Pro\u2019s Guide to Breaker Coordination (and Avoiding a \u201cFair Fight\u201d)"},"content":{"rendered":"<div class=\"product-intro\">\n<p><img fetchpriority=\"high\" decoding=\"async\" class=\"alignnone size-full wp-image-19989\" src=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22.webp\" alt=\"What is &quot;Selectivity&quot;\" width=\"800\" height=\"800\" srcset=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22.webp 800w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22-300x300.webp 300w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22-150x150.webp 150w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22-768x768.webp 768w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22-12x12.webp 12w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22-600x600.webp 600w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/What-is-22Selectivity22-100x100.webp 100w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><\/p>\n<p>\u101c\u103b\u103e\u1015\u103a\u1005\u1005\u103a\u1021\u1004\u103a\u1002\u103b\u1004\u103a\u1014\u102e\u101a\u102c\u101e\u1004\u103a\u1010\u1014\u103a\u1038\u101e\u102c\u1038\u1010\u1005\u103a\u1026\u1038\u1000 \u201c\u1000\u103b\u103d\u1014\u103a\u1010\u1031\u102c\u1037\u103a\u101b\u1032\u1037 \u101c\u103b\u103e\u1015\u103a\u1005\u1005\u103a\u1013\u102c\u1010\u103a\u1021\u102c\u1038\u1015\u1031\u1038\u1005\u1014\u1005\u103a\u1000 100A \u1015\u102b\u104b \u1000\u103b\u103d\u1014\u103a\u1010\u1031\u102c\u1037\u103a\u1005\u1000\u103a\u101b\u102f\u1036\u101b\u1032\u1037 main breaker \u1000\u101c\u100a\u103a\u1038 100A \u1016\u103c\u1005\u103a\u101e\u1004\u1037\u103a\u1015\u102b\u101e\u101c\u102c\u1038\u201d \u101c\u102d\u102f\u1037\u1019\u1031\u1038\u1015\u102b\u1010\u101a\u103a\u104b\u201d<\/p>\n<p>\u1015\u1011\u1019\u1026\u1038\u1005\u103d\u102c\u104a \u201cMaster-level\u201d \u101c\u103b\u103e\u102d\u102f\u1037\u101d\u103e\u1000\u103a\u1001\u103b\u1000\u103a\u1000\u102d\u102f\u1016\u1031\u102c\u103a\u1015\u103c\u101e\u1031\u102c\u1000\u103c\u1031\u102c\u1004\u1037\u103a \u101d\u1031\u102b\u101f\u102c\u101b\u1000\u102d\u102f\u100a\u1004\u103a\u101e\u102c\u1005\u103d\u102c\u1015\u103c\u1004\u103a\u1015\u1031\u1038\u1000\u103c\u1015\u102b\u1005\u102d\u102f\u1037\u104b \u1005\u1000\u103a\u101b\u102f\u1036 main \u101e\u100a\u103a \u201cMCB\u201d \u1019\u101f\u102f\u1010\u103a\u1015\u102b (a <em>Miniature<\/em> Circuit Breaker\u104a \u201c\u1021\u102d\u1019\u103a\u101e\u102f\u1036\u1038\u201d \u1021\u1019\u103b\u102d\u102f\u1038\u1021\u1005\u102c\u1038)\u104b \u1012\u102b\u101f\u102c <strong>&#8220;<a href=\"https:\/\/test.viox.com\/my\/mccb\/\">MCCB<\/a>&#8220;<\/strong> MCCB <em>(a<\/em> Moulded Case <strong>&#8220;<a href=\"https:\/\/test.viox.com\/my\/complete-guide-to-air-circuit-breakers-acb\/\">ACB<\/a>&#8220;<\/strong> Circuit Breaker) \u101e\u102d\u102f\u1037\u1019\u101f\u102f\u1010\u103a ACB <em>\u101c\u1031<\/em> (an\u201c<\/p>\n<p>Air <em>\u1021\u102d\u1019\u103a<\/em> Circuit Breaker) \u1016\u103c\u1005\u103a\u1015\u102b\u1010\u101a\u103a\u104b \u104e\u1004\u103a\u1038\u1010\u102d\u102f\u1037\u101e\u100a\u103a \"\u1005\u1000\u103a\u1019\u103e\u102f\u101c\u102f\u1015\u103a\u1004\u1014\u103a\u1038\u101e\u102f\u1036\u1038 \u101e\u102c\u1038\u101b\u1032\u1019\u103b\u102c\u1038\" \u1016\u103c\u1005\u103a\u101e\u100a\u103a\u104b <strong>\u201c\u1012\u102b\u1015\u1031\u1019\u101a\u1037\u103a \u1015\u103c\u103f\u1014\u102c\u1000 \u101e\u1030\u1037\u101b\u1032\u1037\u1019\u1031\u1038\u1001\u103d\u1014\u103a\u1038\u1015\u102b\u104b \u101e\u1030\u1000\u201d<\/strong> \u201cFair Fight\u201d.<\/p>\n<p>(100A vs. 100A) \u1000\u102d\u102f\u1021\u1006\u102d\u102f\u1015\u103c\u102f\u1014\u1031\u1015\u102b\u1010\u101a\u103a\u104b<\/p>\n<p>\u101c\u103b\u103e\u1015\u103a\u1005\u1005\u103a\u1000\u102c\u1000\u103d\u101a\u103a\u101b\u1031\u1038\u1019\u103e\u102c \"Fair Fight\" \u1019\u103e\u102c\u1018\u102c\u1016\u103c\u1005\u103a\u1019\u101c\u1032\u104b.<\/p>\n<p>\u60a8 <em>never<\/em> \u1000\u1015\u103a\u1006\u102d\u102f\u1038\u1000\u103c\u102e\u1038\u104b <strong>\u201cFair Fight\u201d \u1000\u102d\u102f\u1019\u101c\u102d\u102f\u1001\u103b\u1004\u103a\u1018\u1030\u1038\u104b \"\u1021\u1006\u1004\u1037\u103a\u1006\u1004\u1037\u103a\" \u1000\u102d\u102f\u101c\u102d\u102f\u1001\u103b\u1004\u103a\u1010\u101a\u103a\u104b \u1012\u102e\u1021\u1010\u103d\u1000\u103a \u1015\u101b\u1031\u102c\u103a\u1016\u1000\u103a\u101b\u103e\u1004\u103a\u1014\u101a\u103a\u1021\u101e\u102f\u1036\u1038\u1021\u1014\u103e\u102f\u1014\u103a\u1038\u1000\u201d<\/strong> \u201cSelectivity\u201d.<\/p>\n<hr \/>\n<h2>\u1016\u103c\u1005\u103a\u1015\u103c\u102e\u1038 \u1015\u102b\u101d\u102b\u1012\u102e\u1007\u102d\u102f\u1004\u103a\u1038\u1019\u103e\u102c \u1018\u102c\u1000\u103c\u1031\u102c\u1004\u1037\u103a\u1021\u101b\u1031\u1038\u1000\u103c\u102e\u1038\u1006\u102f\u1036\u1038\u1021\u101a\u1030\u1021\u1006\u1016\u103c\u1005\u103a\u1010\u101a\u103a\u1006\u102d\u102f\u1010\u102c\u1000\u102d\u102f \u1012\u102e\u1019\u103e\u102c\u1016\u1031\u102c\u103a\u1015\u103c\u1015\u1031\u1038\u1011\u102c\u1038\u1015\u102b\u1010\u101a\u103a\u104b<\/h2>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-19990\" src=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity.webp\" alt=\"The &quot;Water Pipe&quot; Analogy: What is Selectivity?\" width=\"800\" height=\"800\" srcset=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity.webp 800w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity-300x300.webp 300w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity-150x150.webp 150w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity-768x768.webp 768w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity-12x12.webp 12w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity-600x600.webp 600w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Water-Pipe22-Analogy-What-is-Selectivity-100x100.webp 100w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><\/p>\n<p><strong>\u101b\u103d\u1031\u1038\u1001\u103b\u101a\u103a\u1019\u103e\u102f<\/strong> \u201c\u101b\u1031\u1015\u102d\u102f\u1000\u103a\u201d \u1025\u1015\u1019\u102c- Selectivity \u1006\u102d\u102f\u1010\u102c\u1018\u102c\u101c\u1032\u104b <em>(\u201cDiscrimination\u201d \u101c\u102d\u102f\u1037\u101c\u100a\u103a\u1038\u1001\u1031\u102b\u103a\u1010\u101a\u103a) \u1006\u102d\u102f\u101e\u100a\u103a\u1019\u103e\u102c<\/em> \u1021\u101e\u1031\u1038\u1006\u102f\u1036\u1038 <em>breaker (\u1010\u1005\u103a\u1001\u102f<\/em> \u1021\u1014\u102e\u1038\u1006\u102f\u1036\u1038 <em>first<\/em>.<\/p>\n<p>\u1001\u103b\u102d\u102f\u1037\u101a\u103d\u1004\u103a\u1038\u1001\u103b\u1000\u103a) \u1001\u101b\u102e\u1038\u1005\u1009\u103a\u1019\u103b\u102c\u1038 <strong>\u201cAha!\u2018 \u1021\u1001\u102d\u102f\u1000\u103a\u1021\u1010\u1014\u1037\u103a\u1000\u1010\u1031\u102c\u1037\u2019<\/strong><\/p>\n<ul>\n<li><strong>\u201c\u101b\u1031\u1015\u102d\u102f\u1000\u103a\u201d \u1025\u1015\u1019\u102c\u104b<\/strong> This is the <strong>\u201cUtility Fuse (100A):\u201d<\/strong> \u201c\u1019\u103c\u102d\u102f\u1037\u101b\u1031\u1019\u1014\u103a\u1038\u201d.<\/li>\n<li><strong>\u101c\u1019\u103a\u1038\u1021\u1031\u102c\u1000\u103a\u1019\u103e\u102c\u104b<\/strong> This is the <strong>\u201c\u101e\u1004\u1037\u103a Main Breaker (80A):\u201d<\/strong> \u201c\u1011\u1031\u102c\u1004\u1037\u103a\u1021\u1006\u102d\u102f\u1037\u101b\u103e\u1004\u103a\u201d.<\/li>\n<li><strong>The Fault:<\/strong> \u1019\u102e\u1038\u1016\u102d\u102f\u1001\u103b\u1031\u102c\u1004\u103a\u1021\u1031\u102c\u1000\u103a\u1019\u103e\u102c\u104b.<\/li>\n<\/ul>\n<p><strong>\u101e\u1004\u1037\u103a\u1019\u102e\u1038\u1016\u102d\u102f\u1001\u103b\u1031\u102c\u1004\u103a\u101b\u1031\u1015\u102d\u102f\u1000\u103a\u1000 \u101a\u102d\u102f\u1005\u102d\u1019\u1037\u103a\u1005\u1015\u103c\u102f\u101c\u102c\u1010\u101a\u103a (\u201c\u1001\u103b\u102d\u102f\u1037\u101a\u103d\u1004\u103a\u1038\u1001\u103b\u1000\u103a\u201d)\u104b<\/strong> \u101b\u100a\u103a\u1019\u103e\u1014\u103a\u1038\u1001\u103b\u1000\u103a: <em>\u101e\u1004\u103a\u1000 \u101b\u103d\u1031\u1038\u1001\u103b\u101a\u103a\u1015\u103c\u102e\u1038<\/em> \u201c\u1011\u1031\u102c\u1004\u1037\u103a\u1021\u1006\u102d\u102f\u1037\u101b\u103e\u1004\u103a\u201d \u1000\u102d\u102f\u1015\u102d\u1010\u103a\u1001\u103b\u1004\u103a\u1010\u101a\u103a\u104b \u101e\u1004\u103a\u1000 \u101b\u102d\u102f\u1038\u101b\u103e\u1004\u103a\u1038\u1010\u1032\u1037\u101b\u1031\u1015\u102d\u102f\u1000\u103a\u101a\u102d\u102f\u1005\u102d\u1019\u1037\u103a\u1019\u103e\u102f\u1010\u1005\u103a\u1001\u102f\u1000 \u201c\u1019\u103c\u102d\u102f\u1037\u101b\u1031\u1019\u1014\u103a\u1038\u201d \u1000\u102d\u102f\u1015\u102d\u1010\u103a\u1015\u103c\u102e\u1038 \u101e\u1004\u1037\u103a\u101b\u1032\u1037 <em>never<\/em> \u1005\u1000\u103a\u101b\u102f\u1036\u1010\u1005\u103a\u1001\u102f\u101c\u102f\u1036\u1038\u1000\u102d\u102f <em>\u1021\u1019\u103e\u1031\u102c\u1004\u103a\u1011\u1032\u1000\u102d\u102f\u101b\u1031\u102c\u1000\u103a\u1005\u1031\u1001\u103b\u1004\u103a\u1010\u101a\u103a\u104b<\/em> \u1012\u102b\u1000 \u1021\u1013\u102d\u1000\u1021\u1010\u103d\u1031\u1038\u1021\u1001\u1031\u102b\u103a\u1000\u102d\u102f \u1016\u1031\u102c\u103a\u1011\u102f\u1010\u103a\u1015\u1031\u1038\u1010\u101a\u103a-.<\/p>\n<p>\u201c\u1019\u1004\u103a\u1038\u101f\u102c \u1019\u1004\u103a\u1038\u101f\u102c\u1000\u102d\u102f\u1000\u102c\u1000\u103d\u101a\u103a\u104a \u1004\u102b\u1000 \u1004\u102b\u1037\u101f\u102c\u1000\u102d\u102f\u1000\u102c\u1000\u103d\u101a\u103a\u1019\u101a\u103a\u104b\u201d <strong>\u201cUtility \u101b\u1032\u1037 100A fuse \u1000\u201d<\/strong> \u101e\u1030\u1010\u102d\u102f\u1037\u101b\u1032\u1037 <em>transformer \u1000\u102d\u102f<\/em> \u1019\u1004\u103a\u1038\u101b\u1032\u1037 <em>\u1019\u102e\u1038\u101c\u1031\u102c\u1004\u103a\u1019\u103e\u102f\u1000\u1014\u1031\u1000\u102c\u1000\u103d\u101a\u103a\u1016\u102d\u102f\u1037\u101b\u103e\u102d\u1010\u101a\u103a\u104b \u101e\u1004\u1037\u103a\u101b\u1032\u1037 80A breaker \u1000<\/em> panel \u1000\u102d\u102f \u101e\u1004\u1037\u103a\u1005\u1000\u103a\u101b\u1032\u1037\u1001\u103b\u102d\u102f\u1037\u101a\u103d\u1004\u103a\u1038\u1001\u103b\u1000\u103a\u1000\u1014\u1031\u1000\u102c\u1000\u103d\u101a\u103a\u1016\u102d\u102f\u1037\u101b\u103e\u102d\u1010\u101a\u103a\u104b \u101e\u1030\u1010\u102d\u102f\u1037\u1000 \u1021\u1016\u103d\u1032\u1037\u1010\u1005\u103a\u1001\u102f\u1010\u100a\u103a\u1038\u1019\u103e\u102c\u1019\u101b\u103e\u102d\u1018\u1030\u1038\u104b <em>\u1019\u102e\u1038\u101c\u1031\u102c\u1004\u103a\u1019\u103e\u102f\u1000\u1014\u1031\u1000\u102c\u1000\u103d\u101a\u103a\u1016\u102d\u102f\u1037\u101b\u103e\u102d\u1010\u101a\u103a\u104b \u101e\u1004\u1037\u103a\u101b\u1032\u1037 80A breaker \u1000<\/em> \u1000\u103c\u1031\u102c\u1000\u103a\u1019\u1000\u103a\u1016\u103d\u101a\u103a\u1007\u102c\u1010\u103a\u101c\u1019\u103a\u1038- \u201c\u101b\u103e\u1000\u103a\u1005\u101b\u102c\u1000\u1031\u102c\u1004\u103a\u1038\u1010\u1032\u1037\u1001\u1031\u102b\u103a\u1006\u102d\u102f\u1019\u103e\u102f\u201d (aka Nuisance Tripping).<\/p>\n<hr \/>\n<h2>\u1012\u102b\u1006\u102d\u102f \u1012\u102e\u1021\u1001\u103b\u1000\u103a\u1000\u102d\u102f\u101c\u103b\u1005\u103a\u101c\u103b\u1030\u101b\u103e\u102f\u101b\u1004\u103a \u1018\u102c\u1016\u103c\u1005\u103a\u1019\u101c\u1032\u104b \u1021\u1032\u1012\u102e \u201cFair Fight\u2018 (100A vs. 100A) \u1000\u102d\u102f\u1016\u1014\u103a\u1010\u102e\u1038\u101b\u1004\u103a \u1018\u102c\u1016\u103c\u1005\u103a\u1019\u101c\u1032\u104b<\/h2>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-19991\" src=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping.webp\" alt=\"The Horror Story- &quot;The 'Shameful Call'&quot; (aka Nuisance Tripping)\" width=\"800\" height=\"800\" srcset=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping.webp 800w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping-300x300.webp 300w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping-150x150.webp 150w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping-768x768.webp 768w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping-12x12.webp 12w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping-600x600.webp 600w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-Horror-Story-22The-Shameful-Call22-aka-Nuisance-Tripping-100x100.webp 100w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><\/p>\n<p>\u1012\u102e \u201c\u1000\u103c\u1031\u102c\u1000\u103a\u1019\u1000\u103a\u1016\u103d\u101a\u103a\u201d \u1021\u1001\u103c\u1031\u1021\u1014\u1031\u1000\u102d\u102f \u101e\u1004\u103a\u101b\u101b\u103e\u102d\u101c\u102d\u1019\u1037\u103a\u1019\u101a\u103a-<\/p>\n<p>\u201cNuisance Tripping\u201d\u104b <strong>\u201c\u1019\u1014\u1000\u103a \u1043 \u1014\u102c\u101b\u102e\u104b \u101e\u1004\u1037\u103a\u101c\u102d\u102f\u1004\u103a\u1038\u1015\u1031\u102b\u103a\u1000 \u1005\u1000\u103a\u1010\u1005\u103a\u101c\u102f\u1036\u1038\u1019\u103e\u102c \u1015\u103c\u1004\u103a\u1038\u1011\u1014\u103a\u1010\u1032\u1037 (\u1012\u102b\u1015\u1031\u1019\u101a\u1037\u103a \u1005\u102e\u1019\u1036\u1014\u102d\u102f\u1004\u103a\u1010\u1032\u1037) short circuit \u1010\u1005\u103a\u1001\u102f\u101b\u103e\u102d\u1010\u101a\u103a\u104b\u201d<\/strong><\/p>\n<p>\u1015\u103c\u102d\u102f\u1004\u103a\u1015\u103d\u1032:.<\/p>\n<p><strong>\u101e\u1004\u1037\u103a\u101b\u1032\u1037 100A main breaker \u1014\u1032\u1037 utility \u101b\u1032\u1037 100A main fuse \u1014\u103e\u1005\u103a\u1001\u102f\u1005\u101c\u102f\u1036\u1038\u1000 \u1000\u103c\u102e\u1038\u1019\u102c\u1038\u1010\u1032\u1037\u1001\u103b\u102d\u102f\u1037\u101a\u103d\u1004\u103a\u1038\u1001\u103b\u1000\u103a\u1000\u102d\u102f\u1019\u103c\u1004\u103a\u1010\u101a\u103a\u104b \u1018\u101a\u103a\u101e\u1030\u1000\u1021\u101b\u1004\u103a\u1001\u101b\u102e\u1038\u1011\u103d\u1000\u103a\u1014\u102d\u102f\u1004\u103a\u1019\u101c\u1032\u1006\u102d\u102f\u1010\u102c\u1000\u102d\u102f \u101e\u1030\u1010\u102d\u102f\u1037\u1000 \u201c\u1015\u103c\u102d\u102f\u1004\u103a\u201d \u1000\u103c\u1010\u101a\u103a\u104b<\/strong> \u201c\u1000\u103c\u1031\u102c\u1000\u103a\u1019\u1000\u103a\u1016\u103d\u101a\u103a\u201d:.<\/p>\n<p><strong>Utility \u101b\u1032\u1037<\/strong> \u1021\u1011\u1000\u103a\u1015\u102d\u102f\u1004\u103a\u1038 <em>fuse \u1000\u1021\u1014\u102d\u102f\u1004\u103a\u101b\u1010\u101a\u103a (\u101e\u102d\u102f\u1037\u1019\u101f\u102f\u1010\u103a \u101e\u1030\u1010\u102d\u102f\u1037\u1014\u103e\u1005\u103a\u101a\u1031\u102c\u1000\u103a\u1005\u101c\u102f\u1036\u1038 \u1001\u101b\u102e\u1038\u1011\u103d\u1000\u103a\u101e\u103d\u102c\u1038\u1010\u101a\u103a)\u104b<\/em> \u1021\u1019\u103e\u1031\u102c\u1004\u103a\u1000\u103b\u101e\u103d\u102c\u1038\u1010\u101a\u103a\u104b.<\/p>\n<p><strong>\u1014\u1031\u102c\u1000\u103a\u1006\u1000\u103a\u1010\u103d\u1032-<\/strong><\/p>\n<ol>\n<li>\u60a8\u7684 <em>\u1021\u1019\u103e\u1031\u102c\u1004\u103a\u1011\u1032\u1000\u102d\u102f\u101b\u1031\u102c\u1000\u103a\u1005\u1031\u1001\u103b\u1004\u103a\u1010\u101a\u103a\u104b<\/em> \u101e\u1004\u1037\u103a main breaker \u1000\u102d\u102f\u1005\u1005\u103a\u1006\u1031\u1038\u1015\u102b\u104b \u1012\u102b\u1000\u2026.<\/li>\n<li>\u1000\u1031\u102c\u1004\u103a\u1038\u1015\u102b\u1010\u101a\u103a\u104b <em>\u101e\u1004\u103a\u1000 utility \u101b\u1032\u1037<\/em>.<\/li>\n<li>You realize the <em>utility\u2019s<\/em> fuse is blown. It\u2019s on a pole 100 meters away.<\/li>\n<li>You must make <strong>\u201cThe \u2018Shameful Call'\u201d<\/strong> to the power company.<\/li>\n<li>You wait 4 hours (in the dark) for a utility truck, who then hands you a $5,000 \u201cemergency call-out\u201d bill for replacing <em>transformer \u1000\u102d\u102f<\/em> fuse that <em>\u1019\u102e\u1038\u101c\u1031\u102c\u1004\u103a\u1019\u103e\u102f\u1000\u1014\u1031\u1000\u102c\u1000\u103d\u101a\u103a\u1016\u102d\u102f\u1037\u101b\u103e\u102d\u1010\u101a\u103a\u104b \u101e\u1004\u1037\u103a\u101b\u1032\u1037 80A breaker \u1000<\/em> bad design blew up.<\/li>\n<\/ol>\n<blockquote><p><strong>\u1000\u103b\u103d\u1019\u103a\u1038\u1000\u103b\u1004\u103a\u101e\u1030 \u1021\u1000\u103c\u1036\u1015\u103c\u102f\u1001\u103b\u1000\u103a-<\/strong> \u60a8 <em>never<\/em> want the utility to be your \u201cfirst line of defense.\u201d That\u2019s <em>\u1019\u102e\u1038\u101c\u1031\u102c\u1004\u103a\u1019\u103e\u102f\u1000\u1014\u1031\u1000\u102c\u1000\u103d\u101a\u103a\u1016\u102d\u102f\u1037\u101b\u103e\u102d\u1010\u101a\u103a\u104b \u101e\u1004\u1037\u103a\u101b\u1032\u1037 80A breaker \u1000<\/em> job. This \u201cnuisance trip\u201d was a \u201ccascading failure\u201d caused by a complete lack of Selectivity.<\/p><\/blockquote>\n<hr \/>\n<h2>The \u201cMaster\u2019s Tool\u201d: Why 80A vs. 100A is the <em>Wrong<\/em> Question<\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-19992\" src=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question.webp\" alt=\"The &quot;Master's Tool&quot;: Why 80A vs. 100A is the Wrong Question\" width=\"800\" height=\"800\" srcset=\"https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question.webp 800w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question-300x300.webp 300w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question-150x150.webp 150w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question-768x768.webp 768w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question-12x12.webp 12w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question-600x600.webp 600w, https:\/\/test.viox.com\/wp-content\/uploads\/2025\/11\/The-22Masters-Tool22-Why-80A-vs.-100A-is-the-Wrong-Question-100x100.webp 100w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/><\/p>\n<p>\u201cOkay, I get it!\u201d the apprentice says. \u201cI\u2019ll just install an 80A breaker to \u2018beat\u2019 their 100A!\u201d<\/p>\n<p>This is the \u201camateur\u2019s\u201d trap. It\u2019s a <em>\u731c\u6d4b\u3002<\/em>.<\/p>\n<p>That 80A breaker <em>\u1016\u103c\u1005\u103a\u1014\u102d\u102f\u1004\u103a\u1010\u101a\u103a<\/em> be selective for a <em>small overload<\/em> (like 90A). But in a <em>massive short circuit<\/em> (e.g., 2,000A), both the 80A and 100A breakers see a \u201c9-alarm fire\u201d and will try to trip <em>\u1001\u103b\u1000\u103a\u1001\u103b\u1004\u103a\u1038<\/em>. You <em>\u4ecd\u7136<\/em> might have a \u201crace condition.\u201d<\/p>\n<p>\u201cAmateurs\u201d guess with <em>Amps<\/em>. \u201cPros\u201d <em>prove<\/em> \u1015\u102b\u101e\u1031\u102c <em>Time<\/em>.<\/p>\n<p>The \u201cMaster\u2019s Tool\u201d is the <strong>Time-Current Curve (TCC)<\/strong>.<\/p>\n<ul>\n<li>This is the \u201cDNA\u201d or \u201creaction-time chart\u201d for every single breaker and fuse.<\/li>\n<li>A \u201cPro\u201d (like a VIOX engineer) performs a <strong>\u201cCoordination Study\u201d<\/strong> \u101e\u102d\u102f\u1037\u1019\u101f\u102f\u1010\u103a <strong>\u201cSelectivity Study.\u201d<\/strong><\/li>\n<li>We overlay the TCC curve of your <em>downstream<\/em> breaker (the \u201cSoldier\u201d) with the TCC curve of the <em>fuse \u1000\u1021\u1014\u102d\u102f\u1004\u103a\u101b\u1010\u101a\u103a (\u101e\u102d\u102f\u1037\u1019\u101f\u102f\u1010\u103a \u101e\u1030\u1010\u102d\u102f\u1037\u1014\u103e\u1005\u103a\u101a\u1031\u102c\u1000\u103a\u1005\u101c\u102f\u1036\u1038 \u1001\u101b\u102e\u1038\u1011\u103d\u1000\u103a\u101e\u103d\u102c\u1038\u1010\u101a\u103a)\u104b<\/em> fuse (the \u201cGeneral\u201d).<\/li>\n<\/ul>\n<p><strong>\u101e\u1004\u1037\u103a\u1019\u102e\u1038\u1016\u102d\u102f\u1001\u103b\u1031\u102c\u1004\u103a\u101b\u1031\u1015\u102d\u102f\u1000\u103a\u1000 \u101a\u102d\u102f\u1005\u102d\u1019\u1037\u103a\u1005\u1015\u103c\u102f\u101c\u102c\u1010\u101a\u103a (\u201c\u1001\u103b\u102d\u102f\u1037\u101a\u103d\u1004\u103a\u1038\u1001\u103b\u1000\u103a\u201d)\u104b<\/strong> We must ensure that for <em>\u1006\u102d\u102f<\/em> given fault (from 100A to 10,000A), the \u201cSoldier\u2019s\u201d curve is <em>always<\/em> <strong>\u201cbelow and to the left\u201d<\/strong> of the \u201cGeneral\u2019s\u201d curve. There should be <em>no white space<\/em> where they overlap.<\/p>\n<p>\u8fd9\u662f\u4e00\u6b21 <em>guarantee<\/em> that our \u201cSoldier\u201d (your VIOX MCCB) will <em>always<\/em> win the \u201crace\u201d and contain the \u201cbattle\u201d <em>before*<\/em> the \u201cGeneral\u201d (the utility fuse) even hears the gunshot.<\/p>\n<hr \/>\n<h2>Conclusion: In Protection, \u201cHierarchy\u201d is \u201cSafety\u201d<\/h2>\n<p>\u60a8 <em>never<\/em> want a <strong>\u201cFair Fight.\u201d<\/strong> You want a <strong>\u201cHierarchy.\u201d<\/strong><\/p>\n<p><strong>\u201cSelectivity\u201d<\/strong> is the art of ensuring your \u201cSoldiers\u201d (your individual breakers) solve the problem <em>long before<\/em> the \u201cGenerals\u201d (your main breaker or the utility) are forced to act.<\/p>\n<p>This is what separates a \u201cprofessional\u201d panel from an \u201camateur\u201d one.<\/p>\n<p>Amateurs guess (80A vs. 100A). Pros <em>calculate<\/em>.<\/p>\n<p>VIOX provides full TCC curve data for all our MCCBs and ACBs, enabling you to design a truly <em>selective<\/em> \u1014\u103e\u1004\u1037\u103a <em>safe<\/em> system. Don\u2019t cause a \u201cShameful Call.\u201d<\/p>\n<p><strong>Design with certainty. Browse our VIOX MCCBs and get the TCC data you need.<\/strong><\/p>\n<hr \/>\n<h3>\u1014\u100a\u103a\u1038\u1015\u100a\u102c\u1015\u102d\u102f\u1004\u103a\u1038\u1021\u101b\u1010\u102d\u1000\u103b\u1019\u103e\u1014\u103a\u1000\u1014\u103a\u1019\u103d\u1010\u1039\u1001\u103a\u1000\u1039<\/h3>\n<pre><code>**Standards &amp; Sources Referenced**\n- This article is based on the core electrical engineering principle of \"Selectivity\" (also \"Discrimination\") as defined by IEC 60364-5-53 and \"Coordination\" as defined by NEC (National Electrical Code) Article 100.\n- The use of Time-Current Curves (TCCs) is the standard industry method for performing a coordination study.\n- The distinction between <a href=\"https:\/\/test.viox.com\/my\/mcb\/\">MCBs<\/a> (Miniature Circuit Breakers, IEC 60898), MCCBs (Moulded Case Circuit Breakers, IEC 60947-2), and ACBs (Air Circuit Breakers, IEC 60947-2) and their applications is correct.\n\n**Timeliness Statement**\nAll technical principles and standards referenced are accurate as of November 2025.\n<\/code><\/pre>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>An apprentice engineer asks, &#8220;My utility supply is 100A. Should my factory&#8217;s main breaker also be 100A?&#8221; First, let&#8217;s gently correct the terminology, as it reveals the &#8220;Master-level&#8221; secret. A factory main isn&#8217;t an &#8220;MCB&#8221; (a Miniature Circuit Breaker, the &#8220;household&#8221; kind). It&#8217;s an &#8220;MCCB&#8220; (a Moulded Case Circuit Breaker) or an &#8220;ACB&#8220; (an Air [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":19996,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[1],"tags":[],"class_list":["post-19987","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"_links":{"self":[{"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/posts\/19987","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/comments?post=19987"}],"version-history":[{"count":4,"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/posts\/19987\/revisions"}],"predecessor-version":[{"id":19995,"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/posts\/19987\/revisions\/19995"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/media\/19996"}],"wp:attachment":[{"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/media?parent=19987"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/categories?post=19987"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/test.viox.com\/my\/wp-json\/wp\/v2\/tags?post=19987"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}