{"id":808,"date":"2025-11-12T10:14:49","date_gmt":"2025-11-12T10:14:49","guid":{"rendered":"https:\/\/instrotech.com\/blog\/?p=808"},"modified":"2026-03-05T14:18:59","modified_gmt":"2026-03-05T14:18:59","slug":"stop-the-guesswork-meggers-true-loop-ends-rcd-uplift-once-and-for-all","status":"publish","type":"post","link":"https:\/\/instrotech.com\/blog\/stop-the-guesswork-meggers-true-loop-ends-rcd-uplift-once-and-for-all\/","title":{"rendered":"Stop the Guesswork: Megger&#8217;s True Loop\u2122 ends RCD uplift"},"content":{"rendered":"\n<div style=\"height:11px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>If you\u2019ve ever tested a circuit and thought, \u201cThat reading can\u2019t be right,\u201d you\u2019ve most likely run into a Residual Current Device (RCD). It\u2019s one of those recurring frustrations, especially when a perfectly good circuit looks like it\u2019s failed.<\/p>\n\n\n\n<p>Loop impedance testing is essential for every install and inspection under the 18th Edition Wiring Regulations, but RCD uplift can throw your readings off. <\/p>\n\n\n\n<p>Here\u2019s why it happens and how Megger\u2019s True Loop\u2122 technology fixes it for good.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What Exactly Is RCD Uplift?<\/h3>\n\n\n\n<div style=\"height:13px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>RCD uplift happens when your loop impedance test shows a higher result than expected because there\u2019s an RCD or RCBO (Residual Current Breaker with Overcurrent protection) in the circuit.<\/p>\n\n\n\n<p>During a non-trip test, the small current from your tester interacts with the RCD\u2019s magnetic coil, which behaves like an extra resistor. The tester can\u2019t separate the two values, so it adds them together.<\/p>\n\n\n\n<p><strong>Example:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>True impedance: 0.7 \u03a9<\/li>\n\n\n\n<li>RCD coil adds: 0.5 \u03a9<\/li>\n\n\n\n<li>Tester shows: 1.2 \u03a9<\/li>\n<\/ul>\n\n\n\n<p>That can make a circuit seem non-compliant when it\u2019s actually safe. To make matters worse, not all RCDs behave the same way, so uplift might appear on one test and not the next.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Why RCD Uplift Actually Matters<\/h3>\n\n\n\n<div style=\"height:13px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p><strong>Safety<\/strong>: If loop impedance (Zs) looks too high, your Prospective Fault Current (PFC) will look too low, which could mean an incorrect assumption about breaker performance.<\/p>\n\n\n\n<p><strong>Compliance<\/strong>: False highs can show safe circuits as failing the Wiring Regs, making certification messy and inconsistent.<\/p>\n\n\n\n<p><strong>Time<\/strong>: You waste hours retesting, chasing faults and double-checking connections, all because uplift has distorted your readings.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">The Solution: Megger True Loop\u2122<\/h3>\n\n\n\n<div style=\"height:13px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div style=\"height:9px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>Megger\u2019s True Loop\u2122 technology, built into testers like the MFT-X1, removes uplift automatically. It identifies the resistance caused by the RCD coil and takes it out of the result, leaving you with the true loop impedance, accurate, compliant and ready to record.<\/p>\n\n\n\n<p>No false fails. No second-guessing. Just proper results.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Confidence from the Confidence Meter\u2122<\/h3>\n\n\n\n<div style=\"height:13px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>The Confidence Meter\u2122 built into the MFT-X1 adds another layer of reassurance. When there\u2019s electrical noise or instability affecting the reading, the screen displays an arc that gradually narrows as the measurement stabilises.<\/p>\n\n\n\n<p>Once it locks into a single point, that\u2019s your confirmation, your reading is accurate and ready to record. It\u2019s simple, visual and genuinely helpful when you\u2019re working under pressure.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Why It Makes a Difference<\/h3>\n\n\n\n<div style=\"height:13px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Accurate readings \u2013 eliminates uplift errors and false fails<\/li>\n\n\n\n<li>Consistent results \u2013 reliable data across circuits and devices<\/li>\n\n\n\n<li>Less wasted time \u2013 no more unnecessary retests or chasing non-existent faults<\/li>\n\n\n\n<li>Safer installs \u2013 dependable Zs and PFC values<\/li>\n<\/ul>\n\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p><strong>Trusted by UK electricians for fast, compliant loop testing. <\/strong><\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<p>RCD uplift has been tripping up electricians (figuratively, thankfully) for years. It\u2019s caused confusion, retests and unnecessary work. <\/p>\n\n\n\n<p>With True Loop\u2122, that\u2019s history.<\/p>\n\n\n\n<p>Accurate loop readings, real compliance and zero guesswork, finally a solution that lets you just get on with the job.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p><a href=\"https:\/\/instrotech.com\/promo\/megger-mft-x1-range.html\" target=\"_blank\" rel=\"noopener\" title=\"Explore our Megger True Loop\u2122 Range\"><strong>Explore our Megger True Loop\u2122 Range<\/strong><\/a><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Related Products<\/strong><\/h2>\n\n\n\n<div class=\"wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-ad2f72ca wp-block-group-is-layout-flex\">\n<div class=\"wp-block-media-text has-media-on-the-right is-stacked-on-mobile\"><div class=\"wp-block-media-text__content\">\n<p><a href=\"https:\/\/instrotech.com\/megger-mft-x1-multifunction-tester.html\" target=\"_blank\" rel=\"noopener\" title=\"Megger MFT-X1, Multifunction Tester\">Megger MFT-X1, Multifunction Tester<\/a><\/p>\n<\/div><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"980\" src=\"https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/product-migration-mft-x1-image-1-10291-1024x980.png\" alt=\"\" class=\"wp-image-816 size-full\" srcset=\"https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/product-migration-mft-x1-image-1-10291-980x938.png 980w, https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/product-migration-mft-x1-image-1-10291-480x459.png 480w\" sizes=\"(min-width: 0px) and (max-width: 480px) 480px, (min-width: 481px) and (max-width: 980px) 980px, (min-width: 981px) 1024px, 100vw\" \/><\/figure><\/div>\n\n\n\n<div class=\"wp-block-media-text has-media-on-the-right is-stacked-on-mobile\"><div class=\"wp-block-media-text__content\">\n<p><a href=\"https:\/\/instrotech.com\/megger-mft-x1-with-evx-adaptor.html\" target=\"_blank\" rel=\"noopener\" title=\"Megger MFT-X1 Test Kit with EVX-100 EVSE Adaptor\">Megger MFT-X1 Test Kit with EVX-100 EVSE Adaptor<\/a><\/p>\n<\/div><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"1000\" height=\"1000\" src=\"https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/megmft-x1-evx-product.jpg\" alt=\"\" class=\"wp-image-821 size-full\" srcset=\"https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/megmft-x1-evx-product.jpg 1000w, https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/megmft-x1-evx-product-980x980.jpg 980w, https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/megmft-x1-evx-product-480x480.jpg 480w\" sizes=\"(min-width: 0px) and (max-width: 480px) 480px, (min-width: 481px) and (max-width: 980px) 980px, (min-width: 981px) 1000px, 100vw\" \/><\/figure><\/div>\n\n\n\n<div class=\"wp-block-media-text has-media-on-the-right is-stacked-on-mobile\"><div class=\"wp-block-media-text__content\">\n<p><a href=\"https:\/\/instrotech.com\/multi-purpose-hard-base-carry-case-acc-for-mft-x1.html\" target=\"_blank\" rel=\"noopener\" title=\"Megger 1014-985, MFT-X1 Multi-purpose Carry Case\">Megger 1014-985, MFT-X1 Multi-purpose Carry Case<\/a><\/p>\n<\/div><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"1000\" height=\"1000\" src=\"https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/meg1014-985.jpg\" alt=\"\" class=\"wp-image-822 size-full\" srcset=\"https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/meg1014-985.jpg 1000w, https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/meg1014-985-980x980.jpg 980w, https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/meg1014-985-480x480.jpg 480w\" sizes=\"(min-width: 0px) and (max-width: 480px) 480px, (min-width: 481px) and (max-width: 980px) 980px, (min-width: 981px) 1000px, 100vw\" 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c-2.552,0-4.622,2.069-4.622,4.622S9.448,16.622,12,16.622s4.622-2.069,4.622-4.622S14.552,7.378,12,7.378z M12,15 c-1.657,0-3-1.343-3-3s1.343-3,3-3s3,1.343,3,3S13.657,15,12,15z M16.804,6.116c-0.596,0-1.08,0.484-1.08,1.08 s0.484,1.08,1.08,1.08c0.596,0,1.08-0.484,1.08-1.08S17.401,6.116,16.804,6.116z\"><\/path><\/svg><span class=\"wp-block-social-link-label screen-reader-text\">Instagram<\/span><\/a><\/li>\n\n<li class=\"wp-social-link wp-social-link-linkedin  wp-block-social-link\"><a href=\"https:\/\/www.linkedin.com\/company\/1298035\/admin\/dashboard\/\" class=\"wp-block-social-link-anchor\"><svg width=\"24\" height=\"24\" viewBox=\"0 0 24 24\" version=\"1.1\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" aria-hidden=\"true\" focusable=\"false\"><path d=\"M19.7,3H4.3C3.582,3,3,3.582,3,4.3v15.4C3,20.418,3.582,21,4.3,21h15.4c0.718,0,1.3-0.582,1.3-1.3V4.3 C21,3.582,20.418,3,19.7,3z M8.339,18.338H5.667v-8.59h2.672V18.338z M7.004,8.574c-0.857,0-1.549-0.694-1.549-1.548 c0-0.855,0.691-1.548,1.549-1.548c0.854,0,1.547,0.694,1.547,1.548C8.551,7.881,7.858,8.574,7.004,8.574z M18.339,18.338h-2.669 v-4.177c0-0.996-0.017-2.278-1.387-2.278c-1.389,0-1.601,1.086-1.601,2.206v4.249h-2.667v-8.59h2.559v1.174h0.037 c0.356-0.675,1.227-1.387,2.526-1.387c2.703,0,3.203,1.779,3.203,4.092V18.338z\"><\/path><\/svg><span class=\"wp-block-social-link-label screen-reader-text\">LinkedIn<\/span><\/a><\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>If you\u2019ve ever tested a circuit and thought, \u201cThat reading can\u2019t be right,\u201d you\u2019ve probably encountered an RCD \u2014 a Residual Current Device. That recurring frustration, when a perfectly good circuit appears to fail, is often down to \u2018RCD uplift\u2019 in loop impedance testing.<\/p>\n","protected":false},"author":5,"featured_media":811,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"off","_et_pb_old_content":"","_et_gb_content_width":"","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"twitterCardType":"","cardImageID":0,"cardImage":"","cardTitle":"","cardDesc":"","cardImageAlt":"","cardPlayer":"","cardPlayerWidth":0,"cardPlayerHeight":0,"cardPlayerStream":"","cardPlayerCodec":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[2],"tags":[11,26,14],"class_list":["post-808","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-installation-testing","tag-18th-edition","tag-megger","tag-multifunction-testers"],"aioseo_notices":[],"jetpack_featured_media_url":"https:\/\/instrotech.com\/blog\/wp-content\/uploads\/2025\/11\/26a7e7b8db653f5e3bd3ca6c2a480d4b.jpg","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p7Siyi-d2","amp_enabled":true,"_links":{"self":[{"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/posts\/808","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/comments?post=808"}],"version-history":[{"count":17,"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/posts\/808\/revisions"}],"predecessor-version":[{"id":869,"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/posts\/808\/revisions\/869"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/media\/811"}],"wp:attachment":[{"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/media?parent=808"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/categories?post=808"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/instrotech.com\/blog\/wp-json\/wp\/v2\/tags?post=808"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}