Which condition makes a three-prong grounding plug unsafe to use?

A three-prong grounding plug serves a crucial safety function by providing a path for electrical current to ground in case of a fault. The design includes two power prongs (live and neutral) and a third prong, which is the grounding prong. When the third prong is intact and properly connected, it significantly reduces the risk of electric shock.

When the third prong is broken off, the grounding feature is rendered ineffective. This means that if there is a short circuit or fault, there is no way for excess electrical current to safely dissipate into the ground, greatly increasing the risk of electrical shock to anyone who comes into contact with the device. Thus, a broken grounding prong presents a significant safety hazard, making the plug unsafe to use.

The other conditions mentioned, such as the length of the prongs, a plastic coating, or incorrect color coding, do not compromise the fundamental safety function of grounding. While they may lead to other issues, they do not directly affect the effectiveness of the grounding feature in a plug. Therefore, the absence of the third prong is what creates an immediate and significant safety concern.