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Old 30th Jul 2014, 9:09 pm   #11
G6Tanuki
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Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,951
Default Re: RCD trip mode question

RCDs can be brought close to the trip-point by modern switch-mode power supplies that have proper EMC filtering/RFI-proofing - a centre-tapped pair of capacitors [ends connected to L and N; centre tap to E].

If you've got a number of such supplies dotted around the place [TVs, radios, microwave-ovens, laundry-appliances] providing 'background' L-N imbalance it then only needs a smidgin of extra leakage to trip a properly-sensitive RCD. Cookers are a favourite trigger, as are infrequently-used convector-heaters kettles irons laundry-appliances and immersion-heaters, all of which can develop excess leakage by way of dampness.
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