100A main breaker tripping with low loading?

[wildgoose]

Your not going to know anything, until you get your test kit out and start going through the system. Just wondering how dedicated circuit RCD'S can trip out the whole DB?? Another reason why you don't always take notice of anyone that has unreliable knowledge of what's happening and when... At the moment no-one can advise you on what's causing the fault(s), the permutations being too many!!

Engineer54 is spot on. Until you get your test kit out and/or experience it yourself, then take what's described as 'background info only not to be relied on'. My experience of 'information via committee' has not been very reliable in the passed!