For protection against faults of this nature a circuit-breaker is used in place of a fuse. Circuit-breakers offer the following advantages compared to fuses. Unlike fuses which only operate once and need to be replaced a circuit-breaker can be reset.
So, are fuses safer than circuit breakers?
A fuse will only handle the amount of amperage that it is rated for. Circuit breakers can be reset after they trip, which is a huge advantage over fuses, but they don’t add any level of safety. Today, circuit breakers are used in homes instead of fuses. The main reason is because a circuit breaker can be re-used.
Why are some appliances double insulated instead of earthed?
Double insulation. Some appliances, such as vacuum cleaners and electric drills, do not have an earth wire. This is because they have plastic casings, or they have been designed so that the live wire can not touch the casing. As a result, the casing cannot give an electric shock, even if the wires inside become loose.