The electric safety device that easily melts when there is overheating or overloading in the circuit is a fuse.

Here's why:

* Fuses are designed with a thin wire (often made of lead or tin) that has a specific melting point.

* When an excessive current flows through the circuit, the wire in the fuse heats up.

* If the current exceeds the fuse's rating, the wire melts, breaking the circuit and preventing further damage.

This melting action interrupts the flow of electricity, protecting the wiring and appliances from potential fires or malfunctions.