Which of the following statements is true regarding conduit size in relation to the NEC®?

In the context of the National Electrical Code (NEC®), the statement regarding larger conduits being placed above smaller conduits is grounded in the practical considerations of heat dissipation and accessibility. Larger conduits often contain more conductors, which can generate more heat. By positioning them above smaller conduits, it allows for better air circulation around the larger conduit, thus aiding in heat dissipation, and preventing overheating issues.

Additionally, placing larger conduits above smaller ones helps to maintain a more organized installation. It reduces the chances of smaller conduits being obstructed during maintenance or future additions, which is particularly important in environments where accessibility and safety are paramount. This arrangement ensures that all conduits remain accessible for service and offers a cleaner appearance in the electrical system layout.

In contrast, while insulating conduits may offer some level of protection, it is not sufficient to override the considerations of size and heat when it comes to safe and effective installations as prescribed by the NEC. Thus, adherence to the guidelines about conduit size and placement fosters long-term reliability and safety in electrical systems.