Final answer:
Hot line tools must be tested at high voltages for safety; however, the exact voltage per foot for testing is not provided in the reference information and varies by industry standards.
Step-by-step explanation:
Hot line tools are designed for use in electrical applications where they will be in close proximity to high voltage power lines. These tools are essential for ensuring the safety of workers who must perform maintenance and repair tasks while the lines are energized. It is critical that hot line tools are tested to withstand high voltages to ensure they can protect workers from electrical hazards. While there isn't a universal standard voltage for testing hot line tools as it can vary by manufacturer and regulatory standards, some references suggest that tool testing might use a range as high as hundreds of kilovolts.
From the provided reference information discussing transmission lines and resistance of insulators, it can be inferred that hot line tools must withstand high voltage environments commonly found in the utility industry. However, the specific test voltage per foot for hot line tools is not provided in the mentioned figures and would typically be determined by industry standards and manufacturer specifications.