Which statement about disconnecting means within sight of a transformer is true?

• A. It must be visible to the operator
• B. It must be inside the transformer enclosure
• C. It must be located at the service disconnect only
• D. It must be permanently locked open

Answer: (A)

Disconnection visibility is the safety principle here: the person working on or near a transformer must be able to see the disconnecting means so they can confirm it is de-energized before performing any maintenance. If the switch or breaker that isolates the transformer is visible from where the transformer sits, the operator can easily verify its position and avoid accidental energization.

That’s why the statement about the disconnecting means being visible to the operator is the best choice. It ensures quick, clear confirmation of shutdown, which is essential for safe work. The alternative of placing it inside the transformer enclosure would obscure access and visibility; requiring it only at the service disconnect ignores the need for a local, observable means for the transformer itself; and mandating permanent lockout is not a universal requirement—locking can be used for safety in some situations, but visibility and verifiability of the open position are the core safety concern here.