Only One Fuse Size Right
A fuse in an electrical circuit is like an alert traffic policeman—stopping everything if there's danger. A circuit breaker serves the same purpose, and the right size is installed when the wiring is done.
A policeman uses his brain to tell him when to blow his whistle, but a fuse depends on the size of the little fusible (meltable) metal link that you see under the glass.
If too great an electrical load is added to a circuit, this link will melt and prevent a dangerous overload. If you put in a fuse with too heavy a link, it will not melt in time, and the wiring and equipment may be damaged.
Therefore the right size of fuse is very important, and is something that you should check in your own home.
See the chart above for the right fuse for each size wire.