{"id":19190,"date":"2026-10-17T10:47:56","date_gmt":"2026-10-17T02:47:56","guid":{"rendered":"https:\/\/www.wehopower.com\/news\/power-supply-cable-sizing-long-dc-runs\/"},"modified":"2026-10-19T12:07:45","modified_gmt":"2026-10-19T04:07:45","slug":"power-supply-cable-sizing-long-dc-runs","status":"publish","type":"news","link":"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/","title":{"rendered":"Power Supply Cable Sizing for Long DC Runs: Budget the Complete Circuit"},"content":{"rendered":"<article>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_86 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">\u03a0\u03af\u03bd\u03b1\u03ba\u03b1\u03c2 \u03c0\u03b5\u03c1\u03b9\u03b5\u03c7\u03bf\u03bc\u03ad\u03bd\u03c9\u03bd<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">\u039c\u03c0\u03b1\u03c1\u03ad\u03c4\u03b1<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewbox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewbox=\"0 0 24 24\" version=\"1.2\" baseprofile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1' ><li class='ez-toc-page-1 ez-toc-heading-level-1'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Power_Supply_Cable_Sizing_for_Long_DC_Runs_Budget_the_Complete_Circuit\" >Power Supply Cable Sizing for Long DC Runs: Budget the Complete Circuit<\/a><ul class='ez-toc-list-level-2' ><li class='ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Define_the_complete_circuit_before_selecting_a_conductor\" >Define the complete circuit before selecting a conductor<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#A_worked_example_with_explicit_assumptions\" >A worked example with explicit assumptions<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Keep_the_SD-50B-12_input_and_output_feeders_distinct\" >Keep the SD-50B-12 input and output feeders distinct<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Check_current_capacity_and_termination_independently\" >Check current capacity and termination independently<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Resolve_an_excessive_drop_before_the_order_is_released\" >Resolve an excessive drop before the order is released<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Frequently_asked_questions\" >Frequently asked questions<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Does_a_ten-metre_run_mean_ten_metres_of_conductor\" >Does a ten-metre run mean ten metres of conductor?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Does_a_larger_power_supply_remove_cable_drop\" >Does a larger power supply remove cable drop?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Can_one_voltage-drop_result_approve_the_cable\" >Can one voltage-drop result approve the cable?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.wehopower.com\/el\/news\/power-supply-cable-sizing-long-dc-runs\/#Send_a_feeder_schedule_with_the_power_supply_enquiry\" >Send a feeder schedule with the power supply enquiry<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h1><span class=\"ez-toc-section\" id=\"Power_Supply_Cable_Sizing_for_Long_DC_Runs_Budget_the_Complete_Circuit\"><\/span>Power Supply Cable Sizing for Long DC Runs: Budget the Complete Circuit<span class=\"ez-toc-section-end\"><\/span><\/h1>\n<figure data-image-role=\"application_a\"><img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/i1.wp.com\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/01-application-a-76.png?quality=85&#038;strip=all\" alt=\"Power Supply Cable Sizing for Long DC Runs: Budget the Complete Circuit  title=\" width=\"1536\" height=\"1024\" power supply cable sizing for long dc runs: budget the complete circuit title=\"\"><figcaption>Isolated installation-layout illustration beside a conveyor inspection station. All five supply clamps are empty; the image does not depict a connected DC feeder or measured voltage drop.<\/figcaption><\/figure>\n<p class=\"lead\">Size a long DC power cable against two separate requirements: the receiver must still see an acceptable voltage, and the cable assembly must safely carry the intended current under its installation conditions. For the voltage calculation, include the complete outgoing and return path, plus connections. A power supply that delivers the correct voltage at its own terminals does not guarantee the same voltage at a distant load.<\/p>\n<p>This is a purchasing and layout decision, not only a troubleshooting step. Establish the run length, load behavior and receiver limits before ordering cable, connectors and distribution hardware. Otherwise, a nominally suitable power supply can be paired with a feeder that consumes too much of the available voltage margin.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Define_the_complete_circuit_before_selecting_a_conductor\"><\/span>Define the complete circuit before selecting a conductor<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Draw the source, outgoing conductor, receiver and return conductor. Include the terminal blocks, connectors, protective devices and joints that are actually in that current path. Do not calculate only the distance from the cabinet to the machine and forget the return route.<\/p>\n<p>For a simple two-wire branch carrying a known current, the resistive drop is <strong>\u0394V = I \u00d7 R<sub>loop<\/sub><\/strong>. The loop resistance includes both conductors and the relevant connections. <a href=\"https:\/\/www.victronenergy.com\/media\/pg\/The_Wiring_Unlimited_book\/en\/theory.html\" target=\"_blank\" rel=\"noopener\">The referenced wiring theory guide<\/a> explains that conductor length, cross-section and connection resistance all influence the drop. Use resistance data for the selected cable and applicable conditions rather than a generic wire-size slogan.<\/p>\n<p>Record the receiver&#8217;s minimum operating voltage, its maximum permitted voltage and its steady and transient current requirements. Also establish the source&#8217;s minimum and maximum output under the intended conditions. The remaining margin, not merely the nameplate voltage, is what the feeder can consume.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"A_worked_example_with_explicit_assumptions\"><\/span>A worked example with explicit assumptions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Assume a 12.0 V source, a receiver drawing 2.0 A, and a total circuit resistance of 0.20 \u03a9, including both conductors and connections. These are illustrative values, not measurements from the pictured equipment and not a recommendation for a particular cable size.<\/p>\n<table>\n<thead>\n<tr>\n<th>Calculation<\/th>\n<th>Result<\/th>\n<th>What it tells the buyer<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Voltage drop: 2.0 A \u00d7 0.20 \u03a9<\/td>\n<td>0.40 V<\/td>\n<td>The complete feeder consumes 0.40 V at this assumed current<\/td>\n<\/tr>\n<tr>\n<td>Receiver voltage: 12.0 V \u2212 0.40 V<\/td>\n<td>11.60 V<\/td>\n<td>Compare with the receiver&#8217;s actual permitted range<\/td>\n<\/tr>\n<tr>\n<td>Circuit dissipation: (2.0 A)\u00b2 \u00d7 0.20 \u03a9<\/td>\n<td>0.80 W<\/td>\n<td>Resistive loss is distributed through the real current path<\/td>\n<\/tr>\n<tr>\n<td>At an assumed 3.0 A with the same resistance<\/td>\n<td>0.60 V drop; 11.40 V at the receiver<\/td>\n<td>A higher-current condition may change the voltage decision<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>A receiver requiring at least 11.5 V would have little margin in the 2.0 A example and would fall below that assumed threshold at 3.0 A. A real assessment must also include source tolerance and the receiver&#8217;s behavior; a constant-power load, for example, cannot always be represented by an unchanged current. Do not treat this table as proof that any installed cable is thermally or electrically acceptable.<\/p>\n<figure data-image-role=\"product_detail\"><img decoding=\"async\" src=\"https:\/\/i1.wp.com\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/03-product-detail-72.png?quality=85&#038;strip=all\" alt=\"Power Supply Cable Sizing for Long DC Runs: Budget the Complete Circuit  title=\" width=\"1536\" height=\"1024\" power supply cable sizing for long dc runs: budget the complete circuit title=\"\"><figcaption>Original reference photographs preserve the actual 4 A label. A different current in family documentation requires revision confirmation, not a rewritten product label.<\/figcaption><\/figure>\n<h2><span class=\"ez-toc-section\" id=\"Keep_the_SD-50B-12_input_and_output_feeders_distinct\"><\/span>Keep the SD-50B-12 input and output feeders distinct<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u039f <a href=\"https:\/\/www.wehopower.com\/el\/product_category\/enclosed-switching-power-supply\/sd-series-dc-dc-power-supply\/\">WEHO SD series<\/a> provides a DC-DC example. The referenced SD-50B-12 label identifies a 24 V DC nominal input with a 19\u201336 V range and a 12 V, 4 A output. It is not an AC-input supply. Its five terminals provide DC input positive and negative, frame ground, and DC output negative and positive.<\/p>\n<p>The available family sheet lists 4.2 A for the 12 V variant, whereas this unit&#8217;s photographed label states 4 A. Do not silently upgrade the pictured unit to the higher value. Confirm the delivered revision and rating with the supplier. The worked example deliberately uses lower, hypothetical currents and does not resolve that documentation difference.<\/p>\n<p>If the input feeder is also long, assess the voltage at the converter&#8217;s input separately. Do not combine input and output conductors into one simple current calculation: a DC-DC converter has distinct input and output conditions. The source evidence does not identify remote-sense terminals, so this guide does not propose remote-sense compensation.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Check_current_capacity_and_termination_independently\"><\/span>Check current capacity and termination independently<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>A small calculated voltage drop does not establish the conductor&#8217;s permitted current in a hot enclosure, a bundle or a particular cable-management system. Obtain the applicable cable rating and installation requirements. Protective-device selection and fault behavior require their own design review.<\/p>\n<p>Check the power supply terminal&#8217;s accepted conductor range and preparation. A cable selected for a long run may be too large for a particular terminal; do not trim away strands to force it to fit. Specify a suitable, documented transition or distribution arrangement and include its connection resistance in the budget. Strain relief and routing should prevent service movement from loading the electrical connection.<\/p>\n<figure data-image-role=\"application_b\"><img decoding=\"async\" src=\"https:\/\/i1.wp.com\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/02-application-b-73.png?quality=85&#038;strip=all\" alt=\"Power Supply Cable Sizing for Long DC Runs: Budget the Complete Circuit  title=\" width=\"1536\" height=\"1024\" power supply cable sizing for long dc runs: budget the complete circuit title=\"\"><figcaption>A separate protected exhibit-service layout illustrates the converter&#x27;s DC input, frame-ground and output interfaces. The shown conductors do not establish an accepted load, measured voltage drop or completed cable-sizing verification.<\/figcaption><\/figure>\n<h2><span class=\"ez-toc-section\" id=\"Resolve_an_excessive_drop_before_the_order_is_released\"><\/span>Resolve an excessive drop before the order is released<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Possible design changes include a shorter route, a conductor with lower resistance, fewer unnecessary joints or a different distribution location. Review each change against the receiver, protection and installation requirements. Moving conversion closer to the load may be an architectural option, but it requires a fresh input, output and environmental assessment.<\/p>\n<p>Do not simply raise the source voltage to compensate for one distant load without checking every receiver and operating state on that branch. A lightly loaded or shorter branch may then see a different voltage condition. Ask the equipment designer to define the acceptable solution and its verification method.<\/p>\n<figure data-image-role=\"engineering_context\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i1.wp.com\/www.wehopower.com\/wp-content\/uploads\/2026\/10\/04-engineering-context-76.png?quality=85&#038;strip=all\" alt=\"Power Supply Cable Sizing for Long DC Runs: Budget the Complete Circuit  title=\" width=\"1536\" height=\"1024\" power supply cable sizing for long dc runs: budget the complete circuit title=\"\"><figcaption>The example uses an assumed total loop resistance. It is not a cable-size table and does not establish installation compliance.<\/figcaption><\/figure>\n<h2><span class=\"ez-toc-section\" id=\"Frequently_asked_questions\"><\/span>Frequently asked questions<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<h3><span class=\"ez-toc-section\" id=\"Does_a_ten-metre_run_mean_ten_metres_of_conductor\"><\/span>Does a ten-metre run mean ten metres of conductor?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Not for a simple two-wire circuit with a ten-metre outward and ten-metre return route. Both conductors contribute resistance. Use the actual route lengths and include connections.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Does_a_larger_power_supply_remove_cable_drop\"><\/span>Does a larger power supply remove cable drop?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>No. More available output current does not remove the resistance between source and receiver. Calculate the feeder against the load and permitted receiver voltage.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Can_one_voltage-drop_result_approve_the_cable\"><\/span>Can one voltage-drop result approve the cable?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>No. Voltage margin, current capacity, termination, protection and installation conditions are separate checks.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Send_a_feeder_schedule_with_the_power_supply_enquiry\"><\/span>Send a feeder schedule with the power supply enquiry<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>Provide the input source range, output load profile, receiver voltage limits, outward and return lengths, proposed cable data and connection list. <a href=\"https:\/\/www.wehopower.com\/el\/contact\/\">\u0395\u03c0\u03b9\u03ba\u03bf\u03b9\u03bd\u03c9\u03bd\u03ae\u03c3\u03c4\u03b5 \u03bc\u03b5 \u03c4\u03b7\u03bd WEHO<\/a> for the converter&#8217;s exact rating and terminal information, and have the equipment designer confirm the cable and protection arrangement before procurement.<\/p>\n<\/article>","protected":false},"excerpt":{"rendered":"<p>A long DC feeder must meet receiver voltage needs and installation current requirements. Start with the full loop.<\/p>","protected":false},"author":2,"featured_media":19186,"parent":0,"menu_order":50,"comment_status":"closed","ping_status":"","template":"","format":"standard","meta":{"_acf_changed":false,"_joinchat":[],"footnotes":""},"news_category":[149,284],"class_list":["post-19190","news","type-news","status-publish","format-standard","has-post-thumbnail","hentry","news_category-blog","news_category-product-articles","entry"],"acf":[],"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/news\/19190","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/types\/news"}],"author":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/comments?post=19190"}],"version-history":[{"count":1,"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/news\/19190\/revisions"}],"predecessor-version":[{"id":19622,"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/news\/19190\/revisions\/19622"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/media\/19186"}],"wp:attachment":[{"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/media?parent=19190"}],"wp:term":[{"taxonomy":"news_category","embeddable":true,"href":"https:\/\/www.wehopower.com\/el\/wp-json\/wp\/v2\/news_category?post=19190"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}