When does an electric short-circuit occur?

Explanation

**Step-by-Step Solution:**

1. **Understanding Electric Circuits**: An electric circuit is a closed loop that allows current to flow through it. It consists of various components such as wires, resistors, and power sources.

2. **Role of Insulation**: Wires in an electric circuit are usually insulated to prevent accidental contact between different wires. This insulation is crucial for the safe operation of electrical systems.

3. **Definition of Short-Circuit**: A short-circuit occurs when there is an unintended path for current to flow, bypassing the normal load (like a light bulb or appliance). This can lead to excessive current flow, which can cause overheating and potentially start a fire.

...