Master Electrician Practice Exam

For underground installations supplying a gasoline dispensing unit, what type of conduit should be used for the last portions of the underground run?

1. Flexible conduit

2. Rigid polyvinyl chloride (PVC)

3. Threaded rigid metal conduit (RMC) or threaded intermediate metal conduit (IMC)

4. Non-metallic conduit

The correct answer is: Threaded rigid metal conduit (RMC) or threaded intermediate metal conduit (IMC)

In underground installations supplying a gasoline dispensing unit, using threaded rigid metal conduit (RMC) or threaded intermediate metal conduit (IMC) is the most appropriate choice for several important reasons. First, RMC and IMC provide a high level of mechanical protection for the conductors inside, which is crucial in an environment where heavy equipment may be in use and where the risk of physical damage is elevated. This is essential around gasoline dispensing units, where safety is a primary concern due to the flammability of gasoline and other fuels. Second, metal conduits are also better suited for environments where there may be exposure to moisture and potentially corrosive substances. The threaded connections of RMC and IMC offer a stronger, more reliable seal against water ingress compared to other types of conduits. This protection is vital in maintaining the integrity of the electrical supply to the dispensing unit, helping to prevent electrical failures or hazardous situations. Additionally, code requirements often specify the use of rigid metal conduit in areas where flammable vapors may be present. This ensures compliance with local, state, and national electrical codes, which are designed to protect safety and minimize risks in potentially hazardous locations. In contrast, other conduit types such as flexible conduit or non-metallic conduit may not