{"id":210438,"date":"2025-04-30T09:30:56","date_gmt":"2025-04-30T09:30:56","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=210438"},"modified":"2025-04-30T09:30:58","modified_gmt":"2025-04-30T09:30:58","slug":"what-is-the-lighting-demand-load-before-derating-for-a-house-with-outside-dimensions-of-30-ft-48-ft-on-the-first-floor-and-22-ft-42-ft-on-the-second-floor","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/04\/30\/what-is-the-lighting-demand-load-before-derating-for-a-house-with-outside-dimensions-of-30-ft-48-ft-on-the-first-floor-and-22-ft-42-ft-on-the-second-floor\/","title":{"rendered":"What is the lighting demand load (before derating) for a house with outside dimensions of 30 ft 48 ft on the first floor and 22 ft 42 ft on the second floor"},"content":{"rendered":"\n

What is the lighting demand load (before derating) for a house with outside dimensions of 30 ft 48 ft on the first floor and 22 ft 42 ft on the second floor? A one-family dwelling has a 175-ampere, 240-volt service that is fed with 75C (167F) conductors. What is the minimum size copper grounding electrode conductor required?<\/p>\n\n\n\n

The correct answer and explanation is :<\/strong><\/mark><\/p>\n\n\n\n

Lighting Demand Load Calculation:<\/h3>\n\n\n\n

To calculate the lighting demand load for the house, we use the National Electrical Code (NEC) guidelines for lighting load calculations. For a dwelling, the general lighting load is based on the square footage of the house.<\/p>\n\n\n\n

    \n
  1. Calculate the total square footage of the house:<\/strong><\/li>\n<\/ol>\n\n\n\n
      \n
    • First floor:<\/strong>
      The first floor has dimensions of 30 feet by 48 feet.
      Total area of the first floor = 30 ft \u00d7 48 ft = 1,440 square feet.<\/li>\n\n\n\n
    • Second floor:<\/strong>
      The second floor has dimensions of 22 feet by 42 feet.
      Total area of the second floor = 22 ft \u00d7 42 ft = 924 square feet.<\/li>\n\n\n\n
    • Total square footage:<\/strong>
      Total area = 1,440 sq ft (first floor) + 924 sq ft (second floor) = 2,364 square feet.<\/li>\n<\/ul>\n\n\n\n
        \n
      1. Lighting load based on NEC Table 220.12:<\/strong>
        According to the NEC, the general lighting load for a dwelling is calculated at 3 volt-amperes (VA) per square foot.<\/li>\n<\/ol>\n\n\n\n
          \n
        • Lighting load = 2,364 sq ft \u00d7 3 VA\/sq ft = 7,092 VA.<\/li>\n<\/ul>\n\n\n\n

          Thus, the lighting demand load for the house (before derating) is 7,092 VA<\/strong> or approximately 7.1 kVA<\/strong>.<\/p>\n\n\n\n

          Minimum Size Copper Grounding Electrode Conductor (GEC):<\/h3>\n\n\n\n

          The grounding electrode conductor size is based on the service size and conductor temperature rating, per NEC Table 250.66.<\/p>\n\n\n\n

            \n
          1. Service Size:<\/strong>
            The house has a 175-amp, 240-volt service.<\/li>\n\n\n\n
          2. Temperature Rating of Conductors:<\/strong>
            The conductors are rated at 75\u00b0C (167\u00b0F).<\/li>\n\n\n\n
          3. Find the minimum size GEC using NEC Table 250.66:<\/strong>
            According to Table 250.66, for a 175-amp service and 75\u00b0C conductor rating, the minimum required grounding electrode conductor size is based on the ampacity of the service. The value for 175 amps corresponds to a 6 AWG copper conductor<\/strong> for the grounding electrode.<\/li>\n<\/ol>\n\n\n\n

            Therefore, the minimum size copper grounding electrode conductor required is a 6 AWG copper wire<\/strong>.<\/p>\n\n\n\n

            Summary:<\/h3>\n\n\n\n
              \n
            • Lighting demand load:<\/strong> 7,092 VA or 7.1 kVA.<\/li>\n\n\n\n
            • Minimum size copper GEC:<\/strong> 6 AWG.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

              What is the lighting demand load (before derating) for a house with outside dimensions of 30 ft 48 ft on the first floor and 22 ft 42 ft on the second floor? A one-family dwelling has a 175-ampere, 240-volt service that is fed with 75C (167F) conductors. What is the minimum size copper grounding electrode […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"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":"default","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":[25],"tags":[],"class_list":["post-210438","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/210438","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=210438"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/210438\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=210438"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=210438"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=210438"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}