To limit the probability that an excessive fire load will accumulate in an electrical equipment vault, which could lead to a fire involving the electrical equipment vault to spread to other parts of the building, which could lead to harm to persons.
To limit the probability that a fire involving stored items in an electrical equipment vault will spread to the electrical equipment, which could lead to failure of the electrical equipment, which could lead to failure of building electrical systems [e.g. normal lighting, heating, ventilating, air-conditioning, and elevator systems], which could lead to unsafe conditions, which could lead to harm to persons.