I am searching to increase the sensitivity of my RCCD to induce more frequent tripping and saw this forum...totally opposite of what i m looking for but here is my comment...Increasing RCCD beyond 100mA is dangerous, please avoid doing so, RCCD is installed to save lifes.
If it is due to lightning, a good surge protection device (SPD/TVSS) will be able to solve the problem, increase in surge will be absorb by the device, look for 1 with 10 modes protection if tripping is too frequent, otherwise 7 modes protection device is sufficient for a house and choose 1 with the longest warranty (rules of thumb..length of warranty=quality), my problem was sorted out...using an american brand, Sine Tamer.

Didn't realised this topic is still alive! i have recommended the use of SPD more than 2 years ago, now that another person has recommended to installed SPD, TAKE HIS ADVICE, THAT WILL RESOLVE THE TRIPPING PROBLEM provided if tripping is caused by LIGHTNING!, I have never experience anymore tripping since 2 years ago even during heavy thunder storm.
when install the SPD ..must ask the installer to install before the RCCB, if they say cannot, don't buy!
mine comes with 15 year unlimited warranty but they r more expensive but definitely worth it knowing that i won't encounter smelly and rotten food in my fridge when i come back from outstation because of the nuisance tripping!

Get a good Surge protection device and install b4 the RCCB / in your case B4 ELCB,
I install the American Brand more than 2 yrs ago, has never trip since, best part is their long unlimited warranty of more than 15 years, 1 to 1 exchange, i think Sine Tamer.
unfortunately, i loss the no. of contractor who install for me.

The Max Guard SPD is only a 4 modes protection SPD, go for at least 7 modes protection SPD, there are a few brands in the market, I installed a 10 modes protection SPD. probelm solved