Circuit Breaker Sizing Calculator (MCB & MCCB) | JUTRION<\/title>\n<style>\nbody{margin:0;padding:32px 20px;background:#ffffff;}\n\/* JUTRION calculators \u2014 paste this ONCE into WordPress: Appearance \u2192 Customize \u2192 Additional CSS.\n Everything is scoped under .jt-calc so it never affects the rest of your site. *\/\n.jt-calc{\n --navy:#142c4e; --blue:#008de4; --blue-dark:#0871bd; --blue-soft:#e9f5fd;\n --ink:#172536; --muted:#617186; --line:#dfe7f0; --surface:#ffffff; --panel:#f7fafd;\n --green:#107652; --green-soft:#e5f6ee; --amber:#9a6200; --amber-soft:#fff4da; --bad:#b23524; --bad-soft:#fdece9;\n --mono:ui-monospace,\"SFMono-Regular\",Consolas,monospace;\n max-width:1040px; margin:0 auto; color:var(--ink);\n font-family:Inter,\"Segoe UI\",Arial,sans-serif; line-height:1.6; font-size:16px; -webkit-font-smoothing:antialiased;\n}\n.jt-calc *{box-sizing:border-box}\n.jt-calc .eyebrow{margin:0 0 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the recommended trip curve, and a cable-coordination check on the Ib \u2264 In \u2264 Iz rule. A design starting point \u2014 verify against the load, the cable, the prospective fault current, and local wiring rules.<\/p>\n\n <div class=\"jt-card\">\n <div class=\"jt-grid\">\n <div class=\"jt-inputs\">\n <div class=\"jt-field\"><label>Load<\/label>\n <div class=\"jt-inline\">\n <input type=\"number\" id=\"jt-load\" value=\"25\" min=\"0\" step=\"0.1\" inputmode=\"decimal\" aria-label=\"Load value\">\n <select id=\"jt-unit\" aria-label=\"Load unit\"><option value=\"kw\" selected>kW<\/option><option value=\"kva\">kVA<\/option><option value=\"a\">A (current)<\/option><\/select>\n <\/div>\n <\/div>\n <div class=\"jt-field\"><label>Supply<\/label>\n <div class=\"jt-seg\" id=\"jt-phase\"><button type=\"button\" data-ph=\"3\" aria-pressed=\"true\">Three-phase<\/button><button type=\"button\" data-ph=\"1\" aria-pressed=\"false\">Single-phase<\/button><\/div>\n <\/div>\n <div class=\"jt-two\">\n <div class=\"jt-field\"><label for=\"jt-volt\">Voltage (V)<\/label><input type=\"number\" id=\"jt-volt\" value=\"400\" min=\"1\" step=\"1\" inputmode=\"numeric\"><\/div>\n <div class=\"jt-field\"><label for=\"jt-pf\">Power factor <span>(kW only)<\/span><\/label><input type=\"number\" id=\"jt-pf\" value=\"0.85\" min=\"0.1\" max=\"1\" step=\"0.01\" inputmode=\"decimal\"><\/div>\n <\/div>\n <div class=\"jt-field\"><label for=\"jt-loadtype\">Load character (sets the curve)<\/label>\n <select id=\"jt-loadtype\"><option value=\"B\">Resistive \/ lighting \u2014 low inrush<\/option><option value=\"C\" selected>General purpose \/ sockets \/ small motors<\/option><option value=\"D\">Motors \/ transformers \u2014 high inrush<\/option><\/select>\n <\/div>\n <div class=\"jt-two\">\n <div class=\"jt-field\"><label for=\"jt-iz\">Cable capacity Iz (A) <span>optional<\/span><\/label><input type=\"number\" id=\"jt-iz\" value=\"\" min=\"0\" step=\"0.1\" inputmode=\"decimal\" placeholder=\"tabulated\"><\/div>\n <div class=\"jt-field\"><label for=\"jt-cf\">Correction factor<\/label><input type=\"number\" id=\"jt-cf\" value=\"1.0\" min=\"0.1\" max=\"1\" step=\"0.01\" inputmode=\"decimal\"><\/div>\n <\/div>\n <\/div>\n <div class=\"jt-readout\">\n <div><div class=\"jt-rl\">Design current I<sub>b<\/sub><\/div><div class=\"jt-big\"><span id=\"jt-ib\">42.5<\/span> <span>A<\/span><\/div><\/div>\n <div class=\"jt-rec\"><div class=\"k\">Recommended rating I<sub>n<\/sub><\/div><div class=\"v\"><span id=\"jt-in\">50 A<\/span> <small id=\"jt-class\">MCB<\/small><\/div><\/div>\n <div class=\"jt-rec\"><div class=\"k\">Trip curve<\/div><div class=\"v\" id=\"jt-curve\" style=\"font-size:15px\">Type C (5\u201310 \u00d7 In)<\/div><\/div>\n <div class=\"jt-rec\"><div class=\"k\">Cable coordination \u2014 I<sub>b<\/sub> \u2264 I<sub>n<\/sub> \u2264 I<sub>z<\/sub><\/div><div style=\"margin-top:6px\"><span class=\"jt-pill na\" id=\"jt-coord\">enter Iz<\/span><\/div><\/div>\n <button type=\"button\" class=\"jt-copy\" id=\"jt-copy\">Copy result<\/button>\n <\/div>\n <\/div>\n <\/div>\n\n <div class=\"jt-content\">\n <h2>How breaker sizing works<\/h2>\n <p>A protective device is sized to protect the cable, not just to carry the load. The governing rule in IEC 60364 is a chain of three currents:<\/p>\n <div class=\"jt-eq\">I<sub>b<\/sub> \u2264 I<sub>n<\/sub> \u2264 I<sub>z<\/sub><\/div>\n <p>where <b>I<sub>b<\/sub><\/b> is the design (load) current, <b>I<sub>n<\/sub><\/b> is the breaker rated current, and <b>I<sub>z<\/sub><\/b> is the corrected current-carrying capacity of the conductor. The breaker rating must be at least the load current, and must never exceed what the cable can safely carry. The design current comes from the load:<\/p>\n <div class=\"jt-eq\">Three-phase from kW: I<sub>b<\/sub> = P \/ (\u221a3 \u00d7 V \u00d7 cos \u03c6)\nThree-phase from kVA: I<sub>b<\/sub> = S \/ (\u221a3 \u00d7 V)\nSingle-phase from kW: I<sub>b<\/sub> = P \/ (V \u00d7 cos \u03c6)<\/div>\n\n <h2>Standard ratings: MCB and MCCB<\/h2>\n <div class=\"jt-table-wrap\"><table>\n <thead><tr><th>Device<\/th><th>Standard<\/th><th>Typical rated currents (A)<\/th><\/tr><\/thead>\n <tbody>\n <tr><td>MCB<\/td><td>IEC 60898-1<\/td><td class=\"mono\">6, 10, 13, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125<\/td><\/tr>\n <tr><td>MCCB<\/td><td>IEC 60947-2<\/td><td class=\"mono\">160, 200, 250, 320, 400, 500, 630, 800, 1000, 1250, 1600<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n\n <h2>Choosing the trip curve<\/h2>\n <div class=\"jt-table-wrap\"><table>\n <thead><tr><th>Curve<\/th><th>Instantaneous trip<\/th><th>Typical use<\/th><\/tr><\/thead>\n <tbody>\n <tr><td class=\"mono\">B<\/td><td class=\"mono\">3\u20135 \u00d7 I<sub>n<\/sub><\/td><td>Resistive and lighting loads, long cable runs, low inrush<\/td><\/tr>\n <tr><td class=\"mono\">C<\/td><td class=\"mono\">5\u201310 \u00d7 I<sub>n<\/sub><\/td><td>General distribution, socket circuits, small motors \u2014 the common default<\/td><\/tr>\n <tr><td class=\"mono\">D<\/td><td class=\"mono\">10\u201320 \u00d7 I<sub>n<\/sub><\/td><td>High-inrush loads: motors, transformers, capacitor banks<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n <p>A curve that trips too early nuisance-trips on inrush; one that trips too late may not clear a fault fast enough. On low fault levels or long cables, a lower curve (B) helps meet the required disconnection time, which must be verified with the earth-fault-loop impedance.<\/p>\n\n <h2>The breaker also has to break the fault<\/h2>\n <p>Rating and curve are not the whole selection. The breaker’s rated breaking capacity \u2014 I<sub>cn<\/sub> for an MCB, I<sub>cu<\/sub> \/ I<sub>cs<\/sub> for an MCCB \u2014 must exceed the prospective short-circuit current at its installation point. Determine the fault level from a short-circuit study before finalizing the device.<\/p>\n\n <h2>Frequently asked questions<\/h2>\n <div class=\"jt-faq\">\n <details><summary>How do I choose the breaker rating for a cable?<\/summary><p>Apply I<sub>b<\/sub> \u2264 I<sub>n<\/sub> \u2264 I<sub>z<\/sub>: the rating must be at least the design current and no more than the cable’s corrected current-carrying capacity. Increasing the breaker above the cable capacity to stop tripping is unsafe.<\/p><\/details>\n <details><summary>When do I need an MCCB instead of an MCB?<\/summary><p>Generally above 125 A, or when you need higher breaking capacity, adjustable trip settings, or larger frame sizes.<\/p><\/details>\n <details><summary>B, C or D curve \u2014 which one?<\/summary><p>B for resistive\/lighting and long runs, C for general distribution and small motors, D for high-inrush loads such as motors and transformers.<\/p><\/details>\n <\/div>\n\n <div class=\"jt-cta\">\n <h2>Choose the breaker<\/h2>\n <p>With the rating, curve, and breaking-capacity target set, compare frames, poles, and trip units \u2014 or send the circuit data for a fast recommendation for your market.<\/p>\n <div class=\"jt-cta-btns\">\n <a class=\"jt-btn\" href=\"https:\/\/jutrion.com\/mccb\/\">Explore JUTRION MCCBs<\/a>\n <a class=\"jt-btn ghost\" href=\"https:\/\/jutrion.com\/contact\/\">Get a free quote<\/a>\n <\/div>\n <p class=\"jt-related\">Related products: <a href=\"https:\/\/jutrion.com\/mcb\/\">MCB<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/mccb\/\">MCCB<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/acb\/\">ACB<\/a><\/p>\n <\/div>\n\n <div class=\"jt-std\"><strong>Standards referenced<\/strong>IEC 60898-1 (MCB ratings & B\/C\/D curves) \u00b7 IEC 60947-2 (MCCB) \u00b7 IEC 60364-4-43 \/ 5-52 (Ib \u2264 In \u2264 Iz coordination).<\/div>\n <p class=\"jt-fine\">This calculator provides an engineering estimate for guidance only. Final circuit design, protection coordination, breaking-capacity verification, and product selection must be carried out by a qualified person against the actual load, conductor data, prospective fault current, applicable standards, and the manufacturer’s current datasheet.<\/p>\n <\/div>\n<\/div>\n\n<script>\n(function(){\n var $=function(id){return document.getElementById(id);};\n var load=$('jt-load'),unit=$('jt-unit'),volt=$('jt-volt'),pf=$('jt-pf'),loadtype=$('jt-loadtype'),iz=$('jt-iz'),cf=$('jt-cf'),\n ibEl=$('jt-ib'),inEl=$('jt-in'),classEl=$('jt-class'),curveEl=$('jt-curve'),coordEl=$('jt-coord');\n var phase=3, MCB=[6,10,13,16,20,25,32,40,50,63,80,100,125], MCCB=[160,200,250,320,400,500,630,800,1000,1250,1600], LADDER=MCB.concat(MCCB);\n document.querySelectorAll('#jt-phase button').forEach(function(b){b.addEventListener('click',function(){phase=parseInt(b.dataset.ph,10);document.querySelectorAll('#jt-phase button').forEach(function(x){x.setAttribute('aria-pressed',x===b?'true':'false');});if(phase===1){if(volt.value==='400'||volt.value==='690')volt.value='230';}if(phase===3){if(volt.value==='230')volt.value='400';}calc();});});\n function nextRating(i){for(var k=0;k<LADDER.length;k++){if(LADDER[k]>=i)return LADDER[k];}return null;}\n function calc(){\n var val=parseFloat(load.value),v=parseFloat(volt.value),f=parseFloat(pf.value),ib;\n if(unit.value==='a'){ib=val;}\n else{if(!(v>0)){reset();return;}var base=(phase===3?Math.sqrt(3)*v:v);ib=(unit.value==='kva')?(val*1000)\/base:((f>0)?(val*1000)\/(base*f):NaN);}\n if(!(ib>0)){reset();return;}\n ibEl.textContent=(Math.round(ib*10)\/10).toFixed(1);\n var nr=nextRating(ib);\n if(nr===null){inEl.textContent='> 1600';classEl.textContent='ACB';}else{inEl.textContent=nr+' A';classEl.textContent=nr<=125?'MCB':'MCCB';}\n curveEl.textContent='Type '+loadtype.value+' ('+({B:'3\u20135',C:'5\u201310',D:'10\u201320'})[loadtype.value]+' \u00d7 In)';\n var izv=parseFloat(iz.value),c=parseFloat(cf.value);if(!(c>0))c=1;\n var okIz=(izv>0); if(okIz)okIz=(nr!==null);\n if(okIz){var izc=izv*c;var pass=(ib<=nr?nr<=izc:false);coordEl.className='jt-pill '+(pass?'ok':'no');coordEl.textContent=pass?('PASS \u2014 In '+nr+' A \u2264 Iz '+izc.toFixed(0)+' A'):('CHECK \u2014 In '+nr+' A vs Iz '+izc.toFixed(0)+' A');}\n else{coordEl.className='jt-pill na';coordEl.textContent='enter Iz';}\n }\n function reset(){ibEl.textContent='\u2014';inEl.textContent='\u2014';classEl.textContent='';curveEl.textContent='\u2014';coordEl.className='jt-pill na';coordEl.textContent='enter Iz';}\n [load,unit,volt,pf,loadtype,iz,cf].forEach(function(el){el.addEventListener('input',calc);el.addEventListener('change',calc);});\n $('jt-copy').addEventListener('click',function(){var b=$('jt-copy');var txt='Load: '+load.value+' '+unit.value.toUpperCase()+', '+(phase===3?'3-phase':'1-phase')+', '+volt.value+' V\\nDesign current Ib: '+ibEl.textContent+' A\\nRecommended rating: '+inEl.textContent+' ('+classEl.textContent+')\\nTrip curve: '+curveEl.textContent+'\\nCoordination: '+coordEl.textContent;navigator.clipboard.writeText(txt).then(function(){var o=b.textContent;b.textContent='Copied \u2713';setTimeout(function(){b.textContent=o;},1500);}).catch(function(){b.textContent='Press Ctrl+C';});});\n calc();\n})();\n<\/script>\n\n\n<\/body>\n<\/html>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Circuit Breaker Sizing Calculator (MCB & MCCB) | JUTRION Circuit protection Circuit Breaker Sizing Calculator (MCB & MCCB) Enter the load to get the design current, the next standard breaker rating to IEC 60898-1 \/ 60947-2, the recommended trip curve, and a cable-coordination check on the Ib \u2264 In \u2264 Iz rule. A design starting […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1778,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1774","page","type-page","status-publish","hentry"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1774","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/comments?post=1774"}],"version-history":[{"count":2,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1774\/revisions"}],"predecessor-version":[{"id":1863,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1774\/revisions\/1863"}],"up":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1778"}],"wp:attachment":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/media?parent=1774"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

{"id":1774,"date":"2026-07-27T10:33:27","date_gmt":"2026-07-27T02:33:27","guid":{"rendered":"https:\/\/jutrion.com\/?page_id=1774"},"modified":"2026-08-07T10:57:46","modified_gmt":"2026-08-07T02:57:46","slug":"calculateur-de-dimensionnement-de-disjoncteur","status":"publish","type":"page","link":"https:\/\/jutrion.com\/fr\/tools\/circuit-breaker-sizing-calculator\/","title":{"rendered":"Calculateur de dimensionnement de disjoncteur"},"content":{"rendered":"\n\n\n\n\n\nCircuit Breaker Sizing Calculator (MCB & MCCB) | JUTRION<\/title>\n<style>\nbody{margin:0;padding:32px 20px;background:#ffffff;}\n\/* JUTRION calculators \u2014 paste this ONCE into WordPress: Appearance \u2192 Customize \u2192 Additional CSS.\n Everything is scoped under .jt-calc so it never affects the rest of your site. *\/\n.jt-calc{\n --navy:#142c4e; --blue:#008de4; --blue-dark:#0871bd; --blue-soft:#e9f5fd;\n --ink:#172536; --muted:#617186; --line:#dfe7f0; --surface:#ffffff; --panel:#f7fafd;\n --green:#107652; 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.jt-fine{font-size:13px;color:var(--muted);margin-top:22px}\n\n<\/style>\n<\/head>\n<body>\n\n<div class=\"jt-calc\">\n <p class=\"eyebrow\">Circuit protection<\/p>\n <h1>Circuit Breaker Sizing Calculator (MCB & MCCB)<\/h1>\n <p class=\"tool-lede\">Enter the load to get the design current, the next standard breaker rating to IEC 60898-1 \/ 60947-2, the recommended trip curve, and a cable-coordination check on the Ib \u2264 In \u2264 Iz rule. A design starting point \u2014 verify against the load, the cable, the prospective fault current, and local wiring rules.<\/p>\n\n <div class=\"jt-card\">\n <div class=\"jt-grid\">\n <div class=\"jt-inputs\">\n <div class=\"jt-field\"><label>Load<\/label>\n <div class=\"jt-inline\">\n <input type=\"number\" id=\"jt-load\" value=\"25\" min=\"0\" step=\"0.1\" inputmode=\"decimal\" aria-label=\"Load value\">\n <select id=\"jt-unit\" aria-label=\"Load unit\"><option value=\"kw\" selected>kW<\/option><option value=\"kva\">kVA<\/option><option value=\"a\">A (current)<\/option><\/select>\n <\/div>\n <\/div>\n <div class=\"jt-field\"><label>Supply<\/label>\n <div class=\"jt-seg\" id=\"jt-phase\"><button type=\"button\" data-ph=\"3\" aria-pressed=\"true\">Three-phase<\/button><button type=\"button\" data-ph=\"1\" aria-pressed=\"false\">Single-phase<\/button><\/div>\n <\/div>\n <div class=\"jt-two\">\n <div class=\"jt-field\"><label for=\"jt-volt\">Voltage (V)<\/label><input type=\"number\" id=\"jt-volt\" value=\"400\" min=\"1\" step=\"1\" inputmode=\"numeric\"><\/div>\n <div class=\"jt-field\"><label for=\"jt-pf\">Power factor <span>(kW only)<\/span><\/label><input type=\"number\" id=\"jt-pf\" value=\"0.85\" min=\"0.1\" max=\"1\" step=\"0.01\" inputmode=\"decimal\"><\/div>\n <\/div>\n <div class=\"jt-field\"><label for=\"jt-loadtype\">Load character (sets the curve)<\/label>\n <select id=\"jt-loadtype\"><option value=\"B\">Resistive \/ lighting \u2014 low inrush<\/option><option value=\"C\" selected>General purpose \/ sockets \/ small motors<\/option><option value=\"D\">Motors \/ transformers \u2014 high inrush<\/option><\/select>\n <\/div>\n <div class=\"jt-two\">\n <div class=\"jt-field\"><label for=\"jt-iz\">Cable capacity Iz (A) <span>optional<\/span><\/label><input type=\"number\" id=\"jt-iz\" value=\"\" min=\"0\" step=\"0.1\" inputmode=\"decimal\" placeholder=\"tabulated\"><\/div>\n <div class=\"jt-field\"><label for=\"jt-cf\">Correction factor<\/label><input type=\"number\" id=\"jt-cf\" value=\"1.0\" min=\"0.1\" max=\"1\" step=\"0.01\" inputmode=\"decimal\"><\/div>\n <\/div>\n <\/div>\n <div class=\"jt-readout\">\n <div><div class=\"jt-rl\">Design current I<sub>b<\/sub><\/div><div class=\"jt-big\"><span id=\"jt-ib\">42.5<\/span> <span>A<\/span><\/div><\/div>\n <div class=\"jt-rec\"><div class=\"k\">Recommended rating I<sub>n<\/sub><\/div><div class=\"v\"><span id=\"jt-in\">50 A<\/span> <small id=\"jt-class\">MCB<\/small><\/div><\/div>\n <div class=\"jt-rec\"><div class=\"k\">Trip curve<\/div><div class=\"v\" id=\"jt-curve\" style=\"font-size:15px\">Type C (5\u201310 \u00d7 In)<\/div><\/div>\n <div class=\"jt-rec\"><div class=\"k\">Cable coordination \u2014 I<sub>b<\/sub> \u2264 I<sub>n<\/sub> \u2264 I<sub>z<\/sub><\/div><div style=\"margin-top:6px\"><span class=\"jt-pill na\" id=\"jt-coord\">enter Iz<\/span><\/div><\/div>\n <button type=\"button\" class=\"jt-copy\" id=\"jt-copy\">Copy result<\/button>\n <\/div>\n <\/div>\n <\/div>\n\n <div class=\"jt-content\">\n <h2>How breaker sizing works<\/h2>\n <p>A protective device is sized to protect the cable, not just to carry the load. The governing rule in IEC 60364 is a chain of three currents:<\/p>\n <div class=\"jt-eq\">I<sub>b<\/sub> \u2264 I<sub>n<\/sub> \u2264 I<sub>z<\/sub><\/div>\n <p>where <b>I<sub>b<\/sub><\/b> is the design (load) current, <b>I<sub>n<\/sub><\/b> is the breaker rated current, and <b>I<sub>z<\/sub><\/b> is the corrected current-carrying capacity of the conductor. The breaker rating must be at least the load current, and must never exceed what the cable can safely carry. The design current comes from the load:<\/p>\n <div class=\"jt-eq\">Three-phase from kW: I<sub>b<\/sub> = P \/ (\u221a3 \u00d7 V \u00d7 cos \u03c6)\nThree-phase from kVA: I<sub>b<\/sub> = S \/ (\u221a3 \u00d7 V)\nSingle-phase from kW: I<sub>b<\/sub> = P \/ (V \u00d7 cos \u03c6)<\/div>\n\n <h2>Standard ratings: MCB and MCCB<\/h2>\n <div class=\"jt-table-wrap\"><table>\n <thead><tr><th>Device<\/th><th>Standard<\/th><th>Typical rated currents (A)<\/th><\/tr><\/thead>\n <tbody>\n <tr><td>MCB<\/td><td>IEC 60898-1<\/td><td class=\"mono\">6, 10, 13, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125<\/td><\/tr>\n <tr><td>MCCB<\/td><td>IEC 60947-2<\/td><td class=\"mono\">160, 200, 250, 320, 400, 500, 630, 800, 1000, 1250, 1600<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n\n <h2>Choosing the trip curve<\/h2>\n <div class=\"jt-table-wrap\"><table>\n <thead><tr><th>Curve<\/th><th>Instantaneous trip<\/th><th>Typical use<\/th><\/tr><\/thead>\n <tbody>\n <tr><td class=\"mono\">B<\/td><td class=\"mono\">3\u20135 \u00d7 I<sub>n<\/sub><\/td><td>Resistive and lighting loads, long cable runs, low inrush<\/td><\/tr>\n <tr><td class=\"mono\">C<\/td><td class=\"mono\">5\u201310 \u00d7 I<sub>n<\/sub><\/td><td>General distribution, socket circuits, small motors \u2014 the common default<\/td><\/tr>\n <tr><td class=\"mono\">D<\/td><td class=\"mono\">10\u201320 \u00d7 I<sub>n<\/sub><\/td><td>High-inrush loads: motors, transformers, capacitor banks<\/td><\/tr>\n <\/tbody>\n <\/table><\/div>\n <p>A curve that trips too early nuisance-trips on inrush; one that trips too late may not clear a fault fast enough. On low fault levels or long cables, a lower curve (B) helps meet the required disconnection time, which must be verified with the earth-fault-loop impedance.<\/p>\n\n <h2>The breaker also has to break the fault<\/h2>\n <p>Rating and curve are not the whole selection. The breaker’s rated breaking capacity \u2014 I<sub>cn<\/sub> for an MCB, I<sub>cu<\/sub> \/ I<sub>cs<\/sub> for an MCCB \u2014 must exceed the prospective short-circuit current at its installation point. Determine the fault level from a short-circuit study before finalizing the device.<\/p>\n\n <h2>Frequently asked questions<\/h2>\n <div class=\"jt-faq\">\n <details><summary>How do I choose the breaker rating for a cable?<\/summary><p>Apply I<sub>b<\/sub> \u2264 I<sub>n<\/sub> \u2264 I<sub>z<\/sub>: the rating must be at least the design current and no more than the cable’s corrected current-carrying capacity. Increasing the breaker above the cable capacity to stop tripping is unsafe.<\/p><\/details>\n <details><summary>When do I need an MCCB instead of an MCB?<\/summary><p>Generally above 125 A, or when you need higher breaking capacity, adjustable trip settings, or larger frame sizes.<\/p><\/details>\n <details><summary>B, C or D curve \u2014 which one?<\/summary><p>B for resistive\/lighting and long runs, C for general distribution and small motors, D for high-inrush loads such as motors and transformers.<\/p><\/details>\n <\/div>\n\n <div class=\"jt-cta\">\n <h2>Choose the breaker<\/h2>\n <p>With the rating, curve, and breaking-capacity target set, compare frames, poles, and trip units \u2014 or send the circuit data for a fast recommendation for your market.<\/p>\n <div class=\"jt-cta-btns\">\n <a class=\"jt-btn\" href=\"https:\/\/jutrion.com\/mccb\/\">Explore JUTRION MCCBs<\/a>\n <a class=\"jt-btn ghost\" href=\"https:\/\/jutrion.com\/contact\/\">Get a free quote<\/a>\n <\/div>\n <p class=\"jt-related\">Related products: <a href=\"https:\/\/jutrion.com\/mcb\/\">MCB<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/mccb\/\">MCCB<\/a> \u00b7 <a href=\"https:\/\/jutrion.com\/acb\/\">ACB<\/a><\/p>\n <\/div>\n\n <div class=\"jt-std\"><strong>Standards referenced<\/strong>IEC 60898-1 (MCB ratings & B\/C\/D curves) \u00b7 IEC 60947-2 (MCCB) \u00b7 IEC 60364-4-43 \/ 5-52 (Ib \u2264 In \u2264 Iz coordination).<\/div>\n <p class=\"jt-fine\">This calculator provides an engineering estimate for guidance only. Final circuit design, protection coordination, breaking-capacity verification, and product selection must be carried out by a qualified person against the actual load, conductor data, prospective fault current, applicable standards, and the manufacturer’s current datasheet.<\/p>\n <\/div>\n<\/div>\n\n<script>\n(function(){\n var $=function(id){return document.getElementById(id);};\n var load=$('jt-load'),unit=$('jt-unit'),volt=$('jt-volt'),pf=$('jt-pf'),loadtype=$('jt-loadtype'),iz=$('jt-iz'),cf=$('jt-cf'),\n ibEl=$('jt-ib'),inEl=$('jt-in'),classEl=$('jt-class'),curveEl=$('jt-curve'),coordEl=$('jt-coord');\n var phase=3, MCB=[6,10,13,16,20,25,32,40,50,63,80,100,125], MCCB=[160,200,250,320,400,500,630,800,1000,1250,1600], LADDER=MCB.concat(MCCB);\n document.querySelectorAll('#jt-phase button').forEach(function(b){b.addEventListener('click',function(){phase=parseInt(b.dataset.ph,10);document.querySelectorAll('#jt-phase button').forEach(function(x){x.setAttribute('aria-pressed',x===b?'true':'false');});if(phase===1){if(volt.value==='400'||volt.value==='690')volt.value='230';}if(phase===3){if(volt.value==='230')volt.value='400';}calc();});});\n function nextRating(i){for(var k=0;k<LADDER.length;k++){if(LADDER[k]>=i)return LADDER[k];}return null;}\n function calc(){\n var val=parseFloat(load.value),v=parseFloat(volt.value),f=parseFloat(pf.value),ib;\n if(unit.value==='a'){ib=val;}\n else{if(!(v>0)){reset();return;}var base=(phase===3?Math.sqrt(3)*v:v);ib=(unit.value==='kva')?(val*1000)\/base:((f>0)?(val*1000)\/(base*f):NaN);}\n if(!(ib>0)){reset();return;}\n ibEl.textContent=(Math.round(ib*10)\/10).toFixed(1);\n var nr=nextRating(ib);\n if(nr===null){inEl.textContent='> 1600';classEl.textContent='ACB';}else{inEl.textContent=nr+' A';classEl.textContent=nr<=125?'MCB':'MCCB';}\n curveEl.textContent='Type '+loadtype.value+' ('+({B:'3\u20135',C:'5\u201310',D:'10\u201320'})[loadtype.value]+' \u00d7 In)';\n var izv=parseFloat(iz.value),c=parseFloat(cf.value);if(!(c>0))c=1;\n var okIz=(izv>0); if(okIz)okIz=(nr!==null);\n if(okIz){var izc=izv*c;var pass=(ib<=nr?nr<=izc:false);coordEl.className='jt-pill '+(pass?'ok':'no');coordEl.textContent=pass?('PASS \u2014 In '+nr+' A \u2264 Iz '+izc.toFixed(0)+' A'):('CHECK \u2014 In '+nr+' A vs Iz '+izc.toFixed(0)+' A');}\n else{coordEl.className='jt-pill na';coordEl.textContent='enter Iz';}\n }\n function reset(){ibEl.textContent='\u2014';inEl.textContent='\u2014';classEl.textContent='';curveEl.textContent='\u2014';coordEl.className='jt-pill na';coordEl.textContent='enter Iz';}\n [load,unit,volt,pf,loadtype,iz,cf].forEach(function(el){el.addEventListener('input',calc);el.addEventListener('change',calc);});\n $('jt-copy').addEventListener('click',function(){var b=$('jt-copy');var txt='Load: '+load.value+' '+unit.value.toUpperCase()+', '+(phase===3?'3-phase':'1-phase')+', '+volt.value+' V\\nDesign current Ib: '+ibEl.textContent+' A\\nRecommended rating: '+inEl.textContent+' ('+classEl.textContent+')\\nTrip curve: '+curveEl.textContent+'\\nCoordination: '+coordEl.textContent;navigator.clipboard.writeText(txt).then(function(){var o=b.textContent;b.textContent='Copied \u2713';setTimeout(function(){b.textContent=o;},1500);}).catch(function(){b.textContent='Press Ctrl+C';});});\n calc();\n})();\n<\/script>\n\n\n<\/body>\n<\/html>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Circuit Breaker Sizing Calculator (MCB & MCCB) | JUTRION Circuit protection Circuit Breaker Sizing Calculator (MCB & MCCB) Enter the load to get the design current, the next standard breaker rating to IEC 60898-1 \/ 60947-2, the recommended trip curve, and a cable-coordination check on the Ib \u2264 In \u2264 Iz rule. A design starting […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1778,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1774","page","type-page","status-publish","hentry"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1774","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/comments?post=1774"}],"version-history":[{"count":2,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1774\/revisions"}],"predecessor-version":[{"id":1863,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1774\/revisions\/1863"}],"up":[{"embeddable":true,"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/pages\/1778"}],"wp:attachment":[{"href":"https:\/\/jutrion.com\/fr\/wp-json\/wp\/v2\/media?parent=1774"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}