{"id":100306,"date":"2026-02-15T20:45:12","date_gmt":"2026-02-15T20:45:12","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100306"},"modified":"2026-07-17T14:51:57","modified_gmt":"2026-07-17T14:51:57","slug":"voltage-drop-calculator","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/lv\/calculators\/voltage-drop-calculator\/","title":{"rendered":"Controlled Steady-State Voltage-Drop Record"},"content":{"rendered":"<p><script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Controlled Steady-State Voltage-Drop Record\",\"description\":\"Calculate a documented DC or steady-state AC voltage-drop approximation from user-supplied conductor resistance\/reactance and circuit evidence. No cable size, universal IEC limit or compliance decision is embedded.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/voltage-drop-calculator\/\",\"applicationCategory\":\"EngineeringApplication\",\"operatingSystem\":\"Any\",\"isAccessibleForFree\":true,\"inLanguage\":\"en\"}\n<\/script><br \/>\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Controlled voltage-drop record\",\"item\":\"https:\/\/vibromera.eu\/calculators\/voltage-drop-calculator\/\"}]}\n<\/script><\/p>\n<style>\n#vbm-vd{--ink:#172033;--muted:#566176;--line:#d8dee9;--panel:#fff;--soft:#f5f7fb;--blue:#1459a6;--blue2:#eaf3ff;--green:#176b45;--green2:#eaf8f1;--amber:#8a5a00;--amber2:#fff7df;--red:#a62929;--red2:#fff0f0;color:var(--ink);font:15px\/1.55 system-ui,-apple-system,\"Segoe UI\",sans-serif;max-width:1100px;margin:0 auto;padding:16px;overflow-wrap:anywhere}\n#vbm-vd *{box-sizing:border-box}#vbm-vd h1,#vbm-vd h2,#vbm-vd h3{line-height:1.22;margin:0;color:var(--ink)}#vbm-vd h1{font-size:clamp(1.75rem,4vw,2.55rem)}#vbm-vd h2{font-size:1.35rem;margin-bottom:14px}#vbm-vd h3{font-size:1.05rem;margin-bottom:8px}#vbm-vd p{margin:8px 0}#vbm-vd a{color:var(--blue)}\n.vd-hero{padding:32px 24px;border:1px solid var(--line);border-radius:18px;background:linear-gradient(135deg,#f8fbff,#eef4ff);box-shadow:0 10px 30px rgba(25,55,95,.08)}.vd-kicker{margin:0 0 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summary{font-weight:760;cursor:pointer}.vd-footer{color:var(--muted);font-size:.86rem;text-align:center;margin:20px 0}\n@media(max-width:760px){#vbm-vd{padding:10px}.vd-hero,.vd-panel{padding:16px}.vd-grid,.vd-gates,.vd-results{grid-template-columns:1fr}.vd-full{grid-column:auto}.vd-btn{width:100%}}\n<\/style>\n<p><main id=\"vbm-vd\" aria-labelledby=\"vd-title\"><\/p>\n<header class=\"vd-hero\">\n<p class=\"vd-kicker\">Controlled circuit evidence and engineering approximation<\/p>\n<h1 id=\"vd-title\">Controlled Steady-State Voltage-Drop Record<\/h1>\n<p class=\"vd-sub\">Calculate a documented two-wire DC, single-phase AC or balanced three-phase AC voltage-drop result from the actual conductor resistance and reactance supplied for the declared operating conditions. This worksheet does not size cable, embed a universal IEC limit or issue a compliance decision.<\/p>\n<div class=\"vd-badges\"><span class=\"vd-badge\">User-supplied R and X<\/span><span class=\"vd-badge\">Displacement cos \u03c6<\/span><span class=\"vd-badge\">Explicit AC scope<\/span><span class=\"vd-badge\">No cable recommendation<\/span><\/div>\n<\/header>\n<div class=\"vd-warning\"><strong>Safety boundary:<\/strong> voltage drop is only one cable-design check. Ampacity, installation method, insulation temperature, grouping, harmonics, fault protection, short-circuit withstand, neutral loading, protective-device coordination and equipment limits require a competent electrical design.<\/div>\n<form id=\"vd-form\" novalidate>\n<section class=\"vd-panel\" aria-labelledby=\"vd-input-title\">\n<h2 id=\"vd-input-title\">Circuit, impedance and operating record<\/h2>\n<div class=\"vd-grid\">\n<div class=\"vd-field\"><label for=\"vd-case\">Case \/ calculation ID <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-case\" type=\"text\" autocomplete=\"off\"><span class=\"vd-error\" id=\"vd-err-case\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-circuit\">Circuit \/ cable identifier <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-circuit\" type=\"text\" autocomplete=\"off\"><span class=\"vd-error\" id=\"vd-err-circuit\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-system\">Declared circuit model <span class=\"vd-required\">*<\/span><\/label><select id=\"vd-system\"><option value=\"\">Choose\u2026<\/option><option value=\"dc2\">DC, equal-impedance two-wire loop<\/option><option value=\"ac1\">Single-phase AC, equal-impedance go\/return<\/option><option value=\"ac3\">Balanced three-phase AC, line-to-line<\/option><\/select><span class=\"vd-error\" id=\"vd-err-system\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-voltage\">Sending voltage U <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-voltage\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"V\"><span class=\"vd-help\">Across the two-wire\/single-phase circuit, or line-to-line for three-phase.<\/span><span class=\"vd-error\" id=\"vd-err-voltage\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-current\">Steady-state RMS\/design current I <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-current\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"A\"><span class=\"vd-error\" id=\"vd-err-current\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-length\">One-way conductor length L <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-length\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"m\"><span class=\"vd-error\" id=\"vd-err-length\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-r\">Per-conductor resistance R <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-r\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"\u03a9\/km at declared conditions\"><span class=\"vd-error\" id=\"vd-err-r\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-x\">Per-conductor reactance X <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-x\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"\u03a9\/km; AC only\"><span class=\"vd-error\" id=\"vd-err-x\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-temp\">Conductor operating temperature <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-temp\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"\u00b0C\"><span class=\"vd-error\" id=\"vd-err-temp\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-frequency\">Frequency <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-frequency\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"Hz; AC only\"><span class=\"vd-error\" id=\"vd-err-frequency\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-pf\">Displacement power factor cos \u03c6 <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-pf\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"0 < cos \u03c6 \u2264 1; AC only\"><span class=\"vd-error\" id=\"vd-err-pf\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-reactive\">Reactive state <span class=\"vd-required\">*<\/span><\/label><select id=\"vd-reactive\"><option value=\"\">Choose for AC\u2026<\/option><option value=\"lagging\">Lagging \/ inductive (+X sin \u03c6)<\/option><option value=\"leading\">Leading \/ capacitive (\u2212X sin \u03c6)<\/option><\/select><span class=\"vd-error\" id=\"vd-err-reactive\"><\/span><\/div>\n<div class=\"vd-field vd-full\"><label for=\"vd-input-source\">Voltage\/current method, source and uncertainty <span class=\"vd-required\">*<\/span><\/label><textarea id=\"vd-input-source\" placeholder=\"Measurement\/design record, RMS definition, operating state and uncertainty\"><\/textarea><span class=\"vd-error\" id=\"vd-err-input-source\"><\/span><\/div>\n<div class=\"vd-field vd-full\"><label for=\"vd-imp-source\">R\/X source and applicability <span class=\"vd-required\">*<\/span><\/label><textarea id=\"vd-imp-source\" placeholder=\"Manufacturer\/table\/document, edition, cable construction\/layout, conductor temperature and frequency\"><\/textarea><span class=\"vd-error\" id=\"vd-err-imp-source\"><\/span><\/div>\n<div class=\"vd-field vd-full\"><label for=\"vd-operating\">Steady-state scope and excluded conditions <span class=\"vd-required\">*<\/span><\/label><textarea id=\"vd-operating\" placeholder=\"Normal operating state; balance\/return path; harmonics, starting, switching and transient exclusions\"><\/textarea><span class=\"vd-error\" id=\"vd-err-operating\"><\/span><\/div>\n<div class=\"vd-field vd-full\"><label for=\"vd-reviewer\">Reviewer and date <span class=\"vd-required\">*<\/span><\/label><input id=\"vd-reviewer\" type=\"text\" autocomplete=\"off\"><span class=\"vd-error\" id=\"vd-err-reviewer\"><\/span><\/div>\n<\/p><\/div>\n<\/section>\n<section class=\"vd-panel\" aria-labelledby=\"vd-limit-title\">\n<h2 id=\"vd-limit-title\">Optional controlled permitted-limit comparison<\/h2>\n<p>Leave all four fields blank for arithmetic only. If any field is used, complete the whole controlled record. No percentage is supplied by the worksheet.<\/p>\n<div class=\"vd-grid\">\n<div class=\"vd-field\"><label for=\"vd-limit\">User-entered permitted value<\/label><input id=\"vd-limit\" type=\"text\" inputmode=\"decimal\" autocomplete=\"off\" placeholder=\"%\"><span class=\"vd-error\" id=\"vd-err-limit\"><\/span><\/div>\n<div class=\"vd-field\"><label for=\"vd-limit-rule\">Comparison rule<\/label><select id=\"vd-limit-rule\"><option value=\"\">Choose\u2026<\/option><option value=\"drop\">Positive voltage drop only<\/option><option value=\"absolute\">Absolute voltage change magnitude<\/option><\/select><span class=\"vd-error\" id=\"vd-err-limit-rule\"><\/span><\/div>\n<div class=\"vd-field vd-full\"><label for=\"vd-limit-source\">Controlled document, edition and exact clause\/table<\/label><textarea id=\"vd-limit-source\"><\/textarea><span class=\"vd-error\" id=\"vd-err-limit-source\"><\/span><\/div>\n<div class=\"vd-field vd-full\"><label for=\"vd-limit-scope\">Jurisdiction, supply type, load category and applicability<\/label><textarea id=\"vd-limit-scope\"><\/textarea><span class=\"vd-error\" id=\"vd-err-limit-scope\"><\/span><\/div>\n<\/p><\/div>\n<div class=\"vd-boundary\"><strong>IEC boundary:<\/strong> the official IEC 60364-5-52:2009+AMD1:2024 CSV record identifies Clause 525 and a relevant annex. The complete controlled limits and categories are not reproduced here and remain <strong>NEEDS_LICENSED_SOURCE<\/strong>.<\/div>\n<\/section>\n<section class=\"vd-panel\" aria-labelledby=\"vd-gates-title\">\n<h2 id=\"vd-gates-title\">Eight evidence and applicability gates<\/h2>\n<div class=\"vd-gates\">\n<div class=\"vd-gate\"><label for=\"vd-ev-path\"><input id=\"vd-ev-path\" type=\"checkbox\">Circuit topology, current path and equal go\/return impedance or three-phase balance are verified.<\/label><\/div>\n<div class=\"vd-gate\"><label for=\"vd-ev-voltage\"><input id=\"vd-ev-voltage\" type=\"checkbox\">Voltage definition, RMS current, one-way length, source record and uncertainty are verified.<\/label><\/div>\n<div class=\"vd-gate\"><label for=\"vd-ev-impedance\"><input id=\"vd-ev-impedance\" type=\"checkbox\">R and X match the actual conductor, construction, layout, operating temperature and frequency.<\/label><\/div>\n<div class=\"vd-gate\"><label for=\"vd-ev-pf\"><input id=\"vd-ev-pf\" type=\"checkbox\">For AC, displacement cos \u03c6 and leading\/lagging state are verified; true PF was not substituted.<\/label><\/div>\n<div class=\"vd-gate\"><label for=\"vd-ev-steady\"><input id=\"vd-ev-steady\" type=\"checkbox\">The steady-state approximation is applicable; starting, switching, fault and transient cases are excluded or separately assessed.<\/label><\/div>\n<div class=\"vd-gate\"><label for=\"vd-ev-harmonics\"><input id=\"vd-ev-harmonics\" type=\"checkbox\">Balance, neutral current, harmonics, skin\/proximity effects and parallel paths are absent or already included in the impedance\/current evidence.<\/label><\/div>\n<div class=\"vd-gate\"><label for=\"vd-ev-limit\"><input id=\"vd-ev-limit\" type=\"checkbox\">No compliance limit is needed, or the entered limit, edition, clause, jurisdiction and category are controlled and applicable.<\/label><\/div>\n<div class=\"vd-gate\"><label for=\"vd-ev-review\"><input id=\"vd-ev-review\" type=\"checkbox\">A competent reviewer will retain every input, source and applicability record with the result.<\/label><\/div>\n<\/p><\/div>\n<div class=\"vd-actions\"><button class=\"vd-btn vd-primary\" type=\"submit\">Calculate controlled voltage-drop record<\/button><button class=\"vd-btn vd-secondary\" id=\"vd-clear\" type=\"button\">Clear record<\/button><\/div>\n<div class=\"vd-status\" id=\"vd-status\" data-state=\"empty\" role=\"status\" aria-live=\"polite\">\n<div class=\"vd-status-title\" id=\"vd-status-title\">No current result<\/div>\n<div class=\"vd-status-summary\" id=\"vd-status-summary\">Complete the controlled record and submit explicitly.<\/div>\n<\/div>\n<\/section><\/form>\n<section class=\"vd-panel\" aria-labelledby=\"vd-results-title\">\n<h2 id=\"vd-results-title\">Steady-state approximation and evidence state<\/h2>\n<div class=\"vd-results\">\n<div class=\"vd-card\"><strong>Signed voltage change \u0394U<\/strong><span class=\"vd-value\" id=\"vd-out-drop\">\u2014<\/span><\/div>\n<div class=\"vd-card\"><strong>Signed percentage<\/strong><span class=\"vd-value\" id=\"vd-out-percent\">\u2014<\/span><\/div>\n<div class=\"vd-card\"><strong>Estimated receiving voltage<\/strong><span class=\"vd-value\" id=\"vd-out-receiving\">\u2014<\/span><\/div>\n<div class=\"vd-card\"><strong>Per-conductor R over L<\/strong><span class=\"vd-value\" id=\"vd-out-r\">\u2014<\/span><\/div>\n<div class=\"vd-card\"><strong>Per-conductor X over L<\/strong><span class=\"vd-value\" id=\"vd-out-x\">\u2014<\/span><\/div>\n<div class=\"vd-card\"><strong>Resistive conductor loss<\/strong><span class=\"vd-value\" id=\"vd-out-loss\">\u2014<\/span><\/div>\n<div class=\"vd-card\"><strong>Controlled limit state<\/strong><span class=\"vd-value\" id=\"vd-out-limit\">Not compared<\/span><\/div>\n<div class=\"vd-card\"><strong>Evidence state<\/strong><span class=\"vd-value\" id=\"vd-out-evidence\">0 \/ 8 complete<\/span><\/div>\n<\/p><\/div>\n<div class=\"vd-record\"><strong id=\"vd-result-title\">No calculation record<\/strong><\/p>\n<p id=\"vd-result-summary\">No current numerical result is available.<\/p>\n<\/div>\n<\/section>\n<section class=\"vd-panel\" aria-labelledby=\"vd-formula-title\">\n<h2 id=\"vd-formula-title\">Engineering formula, units and applicability<\/h2>\n<div class=\"vd-formula\">DC two-wire: \u0394U = 2 I L R<\/div>\n<div class=\"vd-formula\">Single-phase AC: \u0394U \u2248 2 I L (R cos \u03c6 \u00b1 X sin \u03c6)<\/div>\n<div class=\"vd-formula\">Balanced three-phase AC: \u0394U<sub>LL<\/sub> \u2248 \u221a3 I L (R cos \u03c6 \u00b1 X sin \u03c6)<\/div>\n<p>L is in km and R\/X are per-conductor \u03a9\/km at the declared operating conditions. Use + for lagging\/inductive and \u2212 for leading\/capacitive current. U is the two-wire\/single-phase voltage or three-phase line-to-line voltage. The percent result is 100\u0394U\/U. Negative \u0394U means the approximation predicts voltage rise.<\/p>\n<div class=\"vd-formula\">P<sub>loss<\/sub> = n I\u00b2 R L; n = 2 for the declared two-wire\/single-phase path and n = 3 for the declared balanced three-phase path<\/div>\n<div class=\"vd-warning\"><strong>Classification:<\/strong> these are documented steady-state engineering relations, not formulas prescribed by IEC 60364. They do not model unbalance, neutral\/harmonic current, motor starting, faults, switching transients, shunt capacitance or protection.<\/div>\n<\/section>\n<section class=\"vd-panel\" aria-labelledby=\"vd-sources-title\">\n<h2 id=\"vd-sources-title\">Source register and permitted use<\/h2>\n<div class=\"vd-table-wrap\">\n<table class=\"vd-table\">\n<thead>\n<tr>\n<th>ID<\/th>\n<th>Official source and lifecycle<\/th>\n<th>Used for<\/th>\n<th>Not used for<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr id=\"source-S1\">\n<td>S1<\/td>\n<td><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/103734\" target=\"_blank\" rel=\"noopener\">IEC 60364-5-52:2009+AMD1:2024 CSV, Edition 3.1<\/a> \u2014 published 2024-11-22, stability 2028; includes COR1:2011<\/td>\n<td>Wiring-system scope and the public record that Clause 525 points to a relevant voltage-drop annex.<\/td>\n<td>Protected limits\/categories: NEEDS_LICENSED_SOURCE; none embedded.<\/td>\n<\/tr>\n<tr id=\"source-S2\">\n<td>S2<\/td>\n<td><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/71891\" target=\"_blank\" rel=\"noopener\">IEC 60228:2023, Edition 4.0<\/a> \u2014 published, stability 2030<\/td>\n<td>Finished cable-conductor resistance scope and existence of Annex B temperature correction guidance.<\/td>\n<td>Protected resistance tables\/factors: NEEDS_LICENSED_SOURCE; none embedded.<\/td>\n<\/tr>\n<tr id=\"source-S3\">\n<td>S3<\/td>\n<td><a href=\"https:\/\/www.electrical-installation.org\/enwiki\/Calculation_of_voltage_drop_in_steady_load_conditions\" target=\"_blank\" rel=\"noopener\">Schneider Electric Electrical Installation Guide \u2014 steady-load voltage drop<\/a><\/td>\n<td>Common R\/X\/cos \u03c6 single-phase and balanced three-phase engineering relations and units.<\/td>\n<td>Not treated as an IEC-prescribed formula or a cable-selection rule.<\/td>\n<\/tr>\n<tr id=\"source-S4\">\n<td>S4<\/td>\n<td><a href=\"https:\/\/www.electrical-installation.org\/enwiki\/Maximum_voltage_drop_limit\" target=\"_blank\" rel=\"noopener\">Schneider Electric Electrical Installation Guide \u2014 maximum voltage-drop limit<\/a><\/td>\n<td>Limits vary by country, supply\/load category and operating state.<\/td>\n<td>No universal 3%\/5% threshold is embedded.<\/td>\n<\/tr>\n<tr id=\"source-S5\">\n<td>S5<\/td>\n<td><a href=\"https:\/\/product-help.se.com\/docs\/PowerLogic-PM8000\/en-us\/content\/13-measurements\/power-factor-pf.htm\" target=\"_blank\" rel=\"noopener\">Schneider Electric PowerLogic PM8000 Help \u2014 PF<\/a>, updated 2026-04-27<\/td>\n<td>True PF includes harmonics; displacement PF concerns the fundamental frequency.<\/td>\n<td>No harmonic-rich case is reduced to cos \u03c6 arithmetic.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/section>\n<section class=\"vd-panel\" aria-labelledby=\"vd-review-title\">\n<h2 id=\"vd-review-title\">Corrections made during review<\/h2>\n<div class=\"vd-notes\">\n<details class=\"vd-note\">\n<summary>Power factor and reactance were restored to the AC model<\/summary>\n<p>The former unity-PF resistive shortcut was removed. AC now requires controlled R, X, displacement cos \u03c6 and leading\/lagging state.<\/p>\n<\/details>\n<details class=\"vd-note\">\n<summary>Physical resistance was separated from the \u221a3 circuit factor<\/summary>\n<p>The output reports per-conductor R\u00b7L and X\u00b7L. It never labels \u221a3R as cable resistance.<\/p>\n<\/details>\n<details class=\"vd-note\">\n<summary>Generic material resistivity and hot-cable shortcut were removed<\/summary>\n<p>No 0.0175\/0.0283 table or add-about-20-percent rule remains. R\/X must come from the actual conductor record at declared conditions.<\/p>\n<\/details>\n<details class=\"vd-note\">\n<summary>Universal 3%\/5% decisions were removed<\/summary>\n<p>An optional comparison exists only for a user-entered controlled limit with edition, clause, jurisdiction, category and comparison rule.<\/p>\n<\/details>\n<details class=\"vd-note\">\n<summary>Cable sizing and presets were removed<\/summary>\n<p>No house, motor, panel or cable-area recommendation is produced; voltage drop alone cannot prove cable suitability.<\/p>\n<\/details>\n<details class=\"vd-note\">\n<summary>Scope, traceability and strict input were added<\/summary>\n<p>Circuit path, voltage definition, temperature, frequency, impedance source, operating state and reviewer are retained; point\/comma decimals are strict.<\/p>\n<\/details>\n<details class=\"vd-note\">\n<summary>Detached automatic state was removed<\/summary>\n<p>No default, auto-calculation, URL state, localStorage, clipboard or dynamic result HTML remains; edits make a result stale.<\/p>\n<\/details>\n<details class=\"vd-note\">\n<summary>FAQ schema and external dependencies were removed<\/summary>\n<p>Detached simplified claims, external fonts and KaTeX no longer create separate or failing content paths.<\/p>\n<\/details><\/div>\n<\/section>\n<p class=\"vd-footer\">Source access and technical review: 17 July 2026. Retain the complete circuit, impedance, limit and reviewer evidence with every result.<\/p>\n<p><\/main><br \/>\n<script>\n(function(){\n  'use strict';\n  var form=document.getElementById('vd-form'),clearButton=document.getElementById('vd-clear'),hasResult=false;\n  var gates=['vd-ev-path','vd-ev-voltage','vd-ev-impedance','vd-ev-pf','vd-ev-steady','vd-ev-harmonics','vd-ev-limit','vd-ev-review'];\n  var outputs=['vd-out-drop','vd-out-percent','vd-out-receiving','vd-out-r','vd-out-x','vd-out-loss'];\n  var fieldIds=['vd-case','vd-circuit','vd-system','vd-voltage','vd-current','vd-length','vd-r','vd-x','vd-temp','vd-frequency','vd-pf','vd-reactive','vd-input-source','vd-imp-source','vd-operating','vd-reviewer','vd-limit','vd-limit-rule','vd-limit-source','vd-limit-scope'];\n  function byId(id){return document.getElementById(id)}\n  function parseStrict(raw){var s=String(raw).trim();if(!\/^[+-]?(?:\\d+(?:[.,]\\d*)?|[.,]\\d+)$\/.test(s)||(\/[.]\/.test(s)&&\/,\/.test(s)))return null;var n=Number(s.replace(',','.'));return Number.isFinite(n)?n:null}\n  function fmt(n,d){if(!Number.isFinite(n))return '\u2014';if(n===0)return '0';var a=Math.abs(n);if(a>=1e12||a<1e-8)return n.toExponential(8);var s=n.toFixed(d===undefined?8:d);return s.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,'')}\n  function setText(id,text){byId(id).textContent=text}\n  function setError(id,text){var node=byId('vd-err-'+id.replace(\/^vd-\/,''));if(node)node.textContent=text||''}\n  function clearErrors(){fieldIds.forEach(function(id){setError(id,'')})}\n  function gateCount(){return gates.filter(function(id){return byId(id).checked}).length}\n  function clearOutputs(){outputs.forEach(function(id){setText(id,'\u2014')});setText('vd-out-limit','Not compared');setText('vd-out-evidence',gateCount()+' \/ 8 complete');setText('vd-result-title','No calculation record');setText('vd-result-summary','No current numerical result is available.')}\n  function setStatus(state,title,summary){byId('vd-status').dataset.state=state;setText('vd-status-title',title);setText('vd-status-summary',summary)}\n  function invalidate(title,summary){hasResult=false;clearOutputs();setStatus('invalid',title,summary)}\n  function markStale(){if(!hasResult)return;hasResult=false;clearOutputs();setStatus('stale','Result is stale','A circuit, source, limit or evidence input changed. Review the record and submit again.')}\n  function requireText(id,errors){if(!byId(id).value.trim()){setError(id,'This field is required.');errors.push(id)}}\n  function syncSystem(){var system=byId('vd-system').value,isAc=system==='ac1'||system==='ac3';['vd-x','vd-frequency','vd-pf','vd-reactive'].forEach(function(id){byId(id).disabled=!isAc;if(!isAc)byId(id).value=''})}\n  form.addEventListener('submit',function(event){\n    event.preventDefault();clearErrors();var errors=[];\n    ['vd-case','vd-circuit','vd-input-source','vd-imp-source','vd-operating','vd-reviewer'].forEach(function(id){requireText(id,errors)});\n    var system=byId('vd-system').value;if(!['dc2','ac1','ac3'].includes(system)){setError('vd-system','Choose a declared circuit model.');errors.push('vd-system')}\n    var voltage=parseStrict(byId('vd-voltage').value),current=parseStrict(byId('vd-current').value),lengthM=parseStrict(byId('vd-length').value),r=parseStrict(byId('vd-r').value),temp=parseStrict(byId('vd-temp').value);\n    if(voltage===null||voltage<=0||voltage>1e9){setError('vd-voltage','Use a positive complete value up to 1e9 V.');errors.push('vd-voltage')}\n    if(current===null||current<=0||current>1e9){setError('vd-current','Use a positive complete value up to 1e9 A.');errors.push('vd-current')}\n    if(lengthM===null||lengthM<=0||lengthM>1e9){setError('vd-length','Use a positive complete value up to 1e9 m.');errors.push('vd-length')}\n    if(r===null||r<=0||r>1e6){setError('vd-r','Use a positive per-conductor resistance up to 1e6 \u03a9\/km.');errors.push('vd-r')}\n    if(temp===null||temp< -273.15||temp>10000){setError('vd-temp','Use a complete \u00b0C value from \u2212273.15 to 10000.');errors.push('vd-temp')}\n    var isAc=system==='ac1'||system==='ac3',x=0,frequency=null,pf=1,reactive='dc';\n    if(isAc){\n      x=parseStrict(byId('vd-x').value);frequency=parseStrict(byId('vd-frequency').value);pf=parseStrict(byId('vd-pf').value);reactive=byId('vd-reactive').value;\n      if(x===null||x<0||x>1e6){setError('vd-x','Use a complete non-negative reactance up to 1e6 \u03a9\/km.');errors.push('vd-x')}\n      if(frequency===null||frequency<=0||frequency>1e6){setError('vd-frequency','Use a positive frequency up to 1e6 Hz.');errors.push('vd-frequency')}\n      if(pf===null||pf<=0||pf>1){setError('vd-pf','Use displacement cos \u03c6 greater than 0 and not above 1.');errors.push('vd-pf')}\n      if(!['lagging','leading'].includes(reactive)){setError('vd-reactive','Choose lagging or leading.');errors.push('vd-reactive')}\n    }\n    var limitRaw=byId('vd-limit').value.trim(),limitRule=byId('vd-limit-rule').value,limitSource=byId('vd-limit-source').value.trim(),limitScope=byId('vd-limit-scope').value.trim(),limitRequested=Boolean(limitRaw||limitRule||limitSource||limitScope),limit=limitRaw?parseStrict(limitRaw):null;\n    if(limitRequested){\n      if(limit===null||limit<=0||limit>1000){setError('vd-limit','Supply a positive permitted percentage up to 1000.');errors.push('vd-limit')}\n      if(!['drop','absolute'].includes(limitRule)){setError('vd-limit-rule','Choose the controlled comparison rule.');errors.push('vd-limit-rule')}\n      if(!limitSource){setError('vd-limit-source','Supply the controlled document, edition and exact clause\/table.');errors.push('vd-limit-source')}\n      if(!limitScope){setError('vd-limit-scope','Supply jurisdiction, supply type, load category and applicability.');errors.push('vd-limit-scope')}\n    }\n    if(errors.length){invalidate('Cannot calculate','Correct '+new Set(errors).size+' highlighted field(s). Previous numerical output has been cleared.');byId(errors[0]).focus();return}\n    var lengthKm=lengthM\/1000,sinPhi=isAc?Math.sqrt(Math.max(0,1-pf*pf)):0,sign=reactive==='leading'?-1:1,k=system==='ac3'?Math.sqrt(3):2,term=isAc?(r*pf+sign*x*sinPhi):r,drop=k*current*lengthKm*term,percent=drop\/voltage*100,receiving=voltage-drop,rTotal=r*lengthKm,xTotal=isAc?x*lengthKm:0,conductors=system==='ac3'?3:2,loss=conductors*current*current*rTotal;\n    var numbers=[drop,percent,receiving,rTotal,xTotal,loss];if(!numbers.every(Number.isFinite)||receiving<=0||Math.abs(percent)>1000||Math.max.apply(Math,numbers.map(Math.abs))>1e100){invalidate('Cannot calculate','The receiving voltage or converted results are outside the documented finite steady-state domain.');return}\n    setText('vd-out-drop',fmt(drop)+' V '+(drop<0?'(voltage rise)':'(voltage drop)'));\n    setText('vd-out-percent',fmt(percent)+' %');setText('vd-out-receiving',fmt(receiving)+' V');setText('vd-out-r',fmt(rTotal)+' \u03a9');setText('vd-out-x',isAc?fmt(xTotal)+' \u03a9':'0 \u03a9 (DC model)');setText('vd-out-loss',fmt(loss)+' W');\n    var limitState='Not compared \u2014 no controlled limit supplied';\n    if(limitRequested){if(limitRule==='drop'&&percent<0)limitState='Not applicable \u2014 model predicts voltage rise';else{var compared=limitRule==='absolute'?Math.abs(percent):percent,inside=compared<=limit;limitState=(inside?'Within':'Exceeds')+' user-entered '+fmt(limit)+' % '+(limitRule==='absolute'?'absolute-change':'positive-drop')+' limit'}}\n    setText('vd-out-limit',limitState);var count=gateCount(),complete=count===8;setText('vd-out-evidence',count+' \/ 8 '+(complete?'complete':'incomplete'));\n    setText('vd-result-title',(complete?'Controlled arithmetic complete; evidence complete':'Arithmetic complete; evidence incomplete'));\n    setText('vd-result-summary','Case '+byId('vd-case').value.trim()+': '+(isAc?'steady-state '+(system==='ac3'?'balanced three-phase line-to-line':'single-phase')+' approximation':'declared equal-conductor two-wire DC relation')+' at '+fmt(temp)+' \u00b0C'+(isAc?' and '+fmt(frequency)+' Hz, displacement cos \u03c6 '+fmt(pf)+' '+reactive:'')+'. '+limitState+'. No cable size or compliance decision is produced.');\n    setStatus(complete?'valid':'incomplete',complete?'Current controlled result':'Arithmetic only \u2014 evidence incomplete',count+' of 8 evidence gates complete. Retain circuit, R\/X'+(limitRequested?', limit':'')+' and reviewer sources.');hasResult=true;\n  });\n  form.addEventListener('input',markStale);form.addEventListener('change',function(event){if(event.target.id==='vd-system')syncSystem();markStale()});\n  clearButton.addEventListener('click',function(){form.reset();syncSystem();clearErrors();clearOutputs();hasResult=false;setStatus('empty','No current result','Complete the controlled record and submit explicitly.');byId('vd-case').focus()});\n  syncSystem();clearOutputs();\n})();\n<\/script><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Calculate a documented DC or steady-state AC voltage-drop approximation from controlled R\/X and circuit evidence. No cable size or universal IEC limit is assigned.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100306","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/calculator\/100306","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":3,"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/calculator\/100306\/revisions"}],"predecessor-version":[{"id":102669,"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/calculator\/100306\/revisions\/102669"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/media?parent=100306"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/categories?post=100306"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/lv\/wp-json\/wp\/v2\/tags?post=100306"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}