Electrician's Licensing Practice Exam

According to NEC, what is the requirement for installing a floor drain in a vault for transformers?

1. All transformers must have a drain installed

2. Only transformers under 100KW require a drain

3. Only transformers over 100KW require a drain

4. Drains are not needed under any circumstances

The correct answer is: Only transformers over 100KW require a drain

The requirement for installing a floor drain in a vault for transformers, as specified by the National Electrical Code (NEC), is that only transformers over a certain size, specifically those over 100 kW, necessitate the presence of a floor drain. This safety measure is implemented to manage and alleviate the potential risks of fluid leakage from larger transformers, which can contain significant amounts of insulating oil. By ensuring that floor drains are only required for transformers of this size, the NEC establishes a balance between safety and practicality. Smaller transformers typically do not contain enough fluid to pose a similar risk, thereby not requiring equivalent drainage measures. This targeted approach allows for effective management of hazardous materials while avoiding unnecessary installation costs for smaller units. Understanding this requirement is essential for compliance with safety standards and for protecting both personnel and equipment in facilities where transformers are used.