Overload Conditions: this condition occurs when to much current is flowing for the installed wiring to handle. There were many fires in the early 20th Century due to this condition because of fuses. Many homeowners would replace fuses with larger rated fuses or even pennies if their fuses get blowing from to much current flow. They would get frustrated and install the higher rated fuse to eliminate the need to travel every two minutes to keep the electric on. The problem with that is evident in the picture to the left. To much current on a wire to small to carry it will result in tremendous heat, then fire. If you still have fuses NEVER replace them with pennies or fuses rated at a higher trip number then the one you are replacing. It is a real good idea to get rid of them and installing a breaker style panel and service.