Originally Posted by StephenC

rcd amperage cant be too small, if you've got residual current its going somewhere it shouldnt and needs stopping. Putting things on the 'other' side of the RCD may get him going but when his boiler bursts into flames and takes about 30 seconds before the mcb goes on overload im sure his christmas will have gotten a whole lot worse.
Not sure where he lives but surely someone can bob round with a megger and have a quick nose around and isolate the problem at least to get some heat in his house (that is if the boiler element aint knackered).