Which of the following is a potential hazard associated with earth leakage?

The hazard associated with earth leakage primarily involves the risk of electrical shocks to humans. Earth leakage occurs when the electrical current unintentionally flows through the earth or grounding system due to a fault in the electrical installation. This can create a situation where the outer casing of appliances or other parts of the system are live, posing a serious risk to anyone who comes into contact with these surfaces.

When the current leaks, it may not always trip a circuit breaker because the amount of leakage may be insufficient to cause a significant change in overall current flow. This means that people could be exposed to electrical potentials significantly above what is safe, increasing the likelihood of experiencing a shock, which can lead to serious injury or even fatality.

In contrast, the other options present potential consequences of different electrical issues but are not directly caused by earth leakage specifically. Overheating of circuits may occur due to excessive current flowing through conductors but does not relate directly to the leakage to earth. Similarly, while reduced efficiency of electrical appliances and complete circuit failure can happen for various reasons, they do not encapsulate the direct and immediate human hazard presented by earth leakage. Thus, the correct answer highlights the critical safety concern of electric shocks due to this phenomenon.