HOLT Electricians Practice Exam

Transformer vaults containing more than what kVA transformer capacity must be provided with a drain?

1. 50 kVA

2. 75 kVA

3. 100 kVA

4. 150 kVA

The correct answer is: 100 kVA

In electrical installations, transformer vaults are designed to house transformers safely while ensuring compliance with safety regulations and to minimize hazards in case of leaks. The specific requirement that mandates a drain in transformer vaults begins at a transformer capacity of 100 kVA. When a transformer has a capacity of 100 kVA or higher, there is an increased risk of fluid leaks, particularly from the transformer oil, which can become a safety hazard and an environmental concern. The implementation of a drain system in these vaults allows for the safe disposal of such fluids, helping to prevent accumulation and potential spills. This is especially critical in areas where environmental regulations are stringent. For transformers operating below 100 kVA, the risks associated with fluid leaks are generally considered manageable without the necessity of a dedicated drainage system. Therefore, the regulation specifically stipulates that a drain is required for transformer capacities of 100 kVA and above to ensure safety and compliance with best practices in electrical engineering.