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How to modify a 16th into 17th Board
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<blockquote data-quote="springcrocus" data-source="post: 263868" data-attributes="member: 935"><p>That's the point I am trying to make. A consumer unit is only rated at 16.5kA because of type-testing. Once you modify it beyond manufacturers recommendations (e.g only use our MCB's etc) then that rating no longer applies and the rating of the lowest suseptible component applies, which is usually 6kA.</p><p></p><p>If your local tranny is only fifty yards away, you could be looking at a Ze of 0.03 or less which would give a PFC of 7.67kA or more. If the next component after the service fuse (likely the isolator switch) is only rated at 6kA then it could fail under fault conditions.</p><p></p><p>I have reconstructed many a CU myself, I was just pointing out the risk if you have a high PFC. If an isolator switch burns up because of high fault current, and you have installed the CU as recommended, then the manufacturer has a problem. If YOU modified the board then YOU have a problem.</p></blockquote><p></p>
[QUOTE="springcrocus, post: 263868, member: 935"] That's the point I am trying to make. A consumer unit is only rated at 16.5kA because of type-testing. Once you modify it beyond manufacturers recommendations (e.g only use our MCB's etc) then that rating no longer applies and the rating of the lowest suseptible component applies, which is usually 6kA. If your local tranny is only fifty yards away, you could be looking at a Ze of 0.03 or less which would give a PFC of 7.67kA or more. If the next component after the service fuse (likely the isolator switch) is only rated at 6kA then it could fail under fault conditions. I have reconstructed many a CU myself, I was just pointing out the risk if you have a high PFC. If an isolator switch burns up because of high fault current, and you have installed the CU as recommended, then the manufacturer has a problem. If YOU modified the board then YOU have a problem. [/QUOTE]
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How to modify a 16th into 17th Board
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