Older houses frequently have wiring that no longer is capable of doing the job. TRS wiring installed in the 1950's in older homes of weatherboard manufacture in particular are prone to switchboard fires or anywhere where wiring is exposed to air. Insulation degrades to the point that short circuits between wires causes fires to break out, often where you can't see them or get to them in time. If you suspect you have such wiring or just want to be sure your wiring is up to scratch, get it checked out. The cost of replacing your home and all it's possessions is much more than the cure.