What type of meters are used for three-phase utility and outdoor conductors?

The correct answer identifies that Category 4 meters are specifically utilized for measuring three-phase utility and outdoor conductors. These meters are designed to handle the complexities associated with three-phase systems, which can involve higher voltage and current levels than single-phase systems. This makes them particularly suited for utility applications, as they not only measure the total consumption of electricity but can also provide insights into the power factor and phase balance, which are vital for the effective management of three-phase electricity distribution.

In outdoor settings, such as utility poles, these meters must also withstand various environmental conditions, including temperature fluctuations, moisture, and physical impacts, which is another reason why Category 4 meters are preferred. They are built with robust functionalities and protections that accommodate these challenges.

While other categories of meters serve different purposes or are designed for lower voltages or simpler applications, they generally lack the necessary specifications required for effectively measuring the performance in three-phase outdoor environments. Understanding this classification helps apprentices grasp the importance of choosing the right equipment for the right application, ensuring safe and accurate electrical measurements.