As previous comments suggest you need to get a qualified electrician in to check the cause of the fault. It could be a number of things. It could be a fault with an appliance, a fault in the wiring or a short to a metal back box. The consumer unit is in need of replacing to 17 th edition , which will give you mcb's and rcd protection. I would advise you get an electrician in and they will find initial fault and also advice you to upgrade the consumer unit. Costly but I feel is necessary.