Under what condition is the use of unprotected EMT permitted?

The use of unprotected EMT (Electrical Metallic Tubing) is permitted when it is in direct contact with the Earth due to its exposure to the ground, which provides a natural grounding mechanism. This condition minimizes the risk of electrical shock or fire hazards that could arise from potential faults in the conductor housed within the tubing.

When EMT is in direct contact with the Earth, it benefits from the grounding properties of the soil, thereby ensuring that any fault currents are safely directed into the ground. This does not require additional protective measures that would typically be necessary if EMT were installed in environments where it could be exposed to physical damage or electrical hazards without grounding.

In contrast, other conditions like being painted, covered with insulation, or above a suspended ceiling may introduce additional risks or complications. For example, painting can lead to corrosion, insulation can trap heat and moisture, and being located above a suspended ceiling can make access challenging, all of which raise safety and compliance concerns that necessitate protection for the EMT.