All regulators for outdoor installations shall be designed, _______ or protected so that operation will not be affected by the elements.

The requirement for regulators in outdoor installations to be designed, installed, or protected from the elements is crucial for ensuring their proper operation and longevity. When regulators are installed correctly, they are typically positioned in a way that minimizes exposure to adverse weather conditions such as rain, snow, or extreme temperatures. This is essential because exposure to these elements can lead to corrosion, freezing, or mechanical failure over time, affecting the regulator's performance and safety.

Additionally, having the regulators protected from the elements can include using protective covers or enclosures that shield them while still allowing for necessary airflow and accessibility for maintenance. This kind of design consideration helps maintain consistent functionality and reduces the risk of malfunctions that could result in unsafe operating conditions.

In contrast, the other options imply actions or states that would not serve the purpose of maintaining regulator functionality and safety. For example, removing a regulator or allowing it to be exposed would increase the risks associated with environmental interference. Therefore, the focus on proper installation and protection directly supports the reliable operation of the regulator in diverse outdoor conditions.