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Student & Learning Zone - City & Guilds
help with questions on 2391
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<blockquote data-quote="Sensai" data-source="post: 501170" data-attributes="member: 33118"><p>OSG Table I1 shows (R1+R2) for 4mm2+1.5mm2 CPC as 16.71mΩ/metre but what you actually need to do is use the 1.5mm2 line conductor column to get 12.10 as your multiplier. Just because the column says line or protective conductor doesn't matter it's the cable size you need to base it on. That's the trick to this question from City and Guilds. So in effect the sum is:</p><p></p><p>(58*12.10)/1000 = 0.70Ω</p><p></p><p>So the multiple choice answer is (c) 0.70Ω</p><p></p><p>Which is well within the maximum of 1.1Ω shown in GN3 Table A4, for the 32A Type B protective device.</p></blockquote><p></p>
[QUOTE="Sensai, post: 501170, member: 33118"] OSG Table I1 shows (R1+R2) for 4mm2+1.5mm2 CPC as 16.71mΩ/metre but what you actually need to do is use the 1.5mm2 line conductor column to get 12.10 as your multiplier. Just because the column says line or protective conductor doesn't matter it's the cable size you need to base it on. That's the trick to this question from City and Guilds. So in effect the sum is: (58*12.10)/1000 = 0.70Ω So the multiple choice answer is (c) 0.70Ω Which is well within the maximum of 1.1Ω shown in GN3 Table A4, for the 32A Type B protective device. [/QUOTE]
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help with questions on 2391
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