Which of the following is NOT a reason for low insulation resistance readings?

Low insulation resistance readings can indicate potential problems in an electrical system, and understanding the factors that contribute to these readings is essential for proper inspection and testing.

Proper installation refers to the adherence to standards and best practices during the setup of electrical systems. This includes ensuring that all components are correctly and securely installed, and that proper materials are used throughout the installation process. When installation is carried out correctly, it minimizes the possibility of faults that could lead to low insulation resistance. Therefore, it is not a factor contributing to low insulation resistance readings, making it the correct answer in this context.

On the other hand, moisture ingress, degradation of insulating materials, and mechanical damage can all adversely affect insulation resistance. Moisture can introduce conductive paths through insulation, while degradation of materials can weaken their insulating properties over time. Mechanical damage can physically compromise insulation integrity, leading to reduced resistance. These factors are common causes of low readings and are indicative of potential issues that need to be addressed during inspection and testing.