Principle

More current consumers increase the strength of the current flow. When current flows through a wire, it heats up. When a second light bulb is switched on, more current flows through the wire: the current strength increases. Short circuit: A short circuit has occurred due to the conductive contact of the stripped connecting wires. The current no longer flows through the bulb, as it has a higher resistance, but takes the shorter route via the point of contact between the wires. As a result of the lower resistance, a stronger current flows and the wire becomes so hot that it glows. Fusible link. The iron wire acts as a fuse, melting when the electrical line is overloaded, thus interrupting the flow of current.