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High Zs
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<blockquote data-quote="mcgaw81" data-source="post: 42771" data-attributes="member: 11"><p>I wired a shower last week and went back to connect it up and test today, however on testing the Zs of the circuit i get a reading of 0.93ohms, and the MCB maximum is 0.92ohms (50amp Type B) in regs, on the back of my NICEIC test books its 80% which allows 0.73ohms.</p><p></p><p>More detail, what I have is a Sub Main supplied in 16mm Twin and Earth from a 60amp switch fuse. I have install new 4 way enclosure with 63amp RCD 50amp MCB (shower) 16amp (1x Double skt).</p><p></p><p>At the top of the RCD i get 0.22ohms, socket is 0.44ohms and the high reading for the shower. Everything else tests ok, my R1+R2 was 0.46ohms. Now i know i could have done my Zs by calculation and would have had a satisfactory result but why is my R1+R2 ok but high Zs.</p><p></p><p>What are my options of reducing this, different Type MCB, maybe type 1? What other options do I have?</p><p></p><p>Thanks in advance.</p></blockquote><p></p>
[QUOTE="mcgaw81, post: 42771, member: 11"] I wired a shower last week and went back to connect it up and test today, however on testing the Zs of the circuit i get a reading of 0.93ohms, and the MCB maximum is 0.92ohms (50amp Type B) in regs, on the back of my NICEIC test books its 80% which allows 0.73ohms. More detail, what I have is a Sub Main supplied in 16mm Twin and Earth from a 60amp switch fuse. I have install new 4 way enclosure with 63amp RCD 50amp MCB (shower) 16amp (1x Double skt). At the top of the RCD i get 0.22ohms, socket is 0.44ohms and the high reading for the shower. Everything else tests ok, my R1+R2 was 0.46ohms. Now i know i could have done my Zs by calculation and would have had a satisfactory result but why is my R1+R2 ok but high Zs. What are my options of reducing this, different Type MCB, maybe type 1? What other options do I have? Thanks in advance. [/QUOTE]
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