After talking to my client on the phone, I suspect the wiring is loose but it turns out that one of his MCB and ELCB is faulty. So we have to replace it and all is normal again. I wish I could help him save the money but it is not the typical screw is loose somewhere scenario. At first I thought it is one of those unlucky client who dealt with unethical electrician who intentionally not tighten to screw in order for electrical parts to sparks then burn to shorten its lifespan in order for their return for the next visit to earn from him again. Nope this is not the case, it really just burned. If you have a need of an electrician in off jalan puchong, please do not hesitate to call us!