Capacitors containing more than __________ of flammable liquid shall be enclosed in vaults or outdoor fenced enclosures.

The correct answer is based on safety regulations pertaining to the storage and containment of capacitors that use flammable liquids. Capacitors that contain more than 3 gallons of flammable liquid must be housed in vaults or outdoor fenced enclosures to mitigate the risks associated with potential leaks or spills. The 3-gallon threshold is established to ensure that proper safety measures are in place, effectively managing the fire risk and protecting both the facility and the surrounding environment from hazardous incidents.

This requirement helps ensure compliance with safety standards, particularly in situations where larger quantities of flammable materials could exacerbate the consequences in case of a failure or accident. Containment measures are crucial for safeguarding personnel and property in environments where such risks are likely to occur.