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Do-It-Yourself (DIY) Question & Answer Forum
Max Zs
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<blockquote data-quote="SPECIAL LOCATION" data-source="post: 22248" data-attributes="member: 250"><p>The values in the little red book OSG</p><p></p><p>are the "rule-of-thumb" 80% values..</p><p></p><p>that allow for increased heat in a conductor during earth fault!</p><p></p><p>NICEIC quote these 80% values as the max value when testing cold conductors..</p><p></p><p>as it is generally accepted that if cold less than 80% of max from Big book..</p><p></p><p>then in the event of a fault the big book max will not be exceeded!</p><p></p><p>{remember cables will heat up during fault!}</p><p></p><p>&amp; thus the MCB will still trip fast enough!</p><p></p><p>BUT the value that goes on your certificate IS the BIG book value NOT osg! <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink ;)" loading="lazy" data-shortname=";)" /> </p><p></p><p>as I was corrected by mr NICEIC man on a previous inspection! :|</p></blockquote><p></p>
[QUOTE="SPECIAL LOCATION, post: 22248, member: 250"] The values in the little red book OSG are the "rule-of-thumb" 80% values.. that allow for increased heat in a conductor during earth fault! NICEIC quote these 80% values as the max value when testing cold conductors.. as it is generally accepted that if cold less than 80% of max from Big book.. then in the event of a fault the big book max will not be exceeded! {remember cables will heat up during fault!} & thus the MCB will still trip fast enough! BUT the value that goes on your certificate IS the BIG book value NOT osg! ;) as I was corrected by mr NICEIC man on a previous inspection! :| [/QUOTE]
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