What safety precaution should be taken before testing individual transformers?

The most important safety precaution before testing individual transformers is to disconnect the power supply. This step is crucial because transformers, when connected to a power supply, can pose serious electrical hazards. Disconnecting the power ensures that there is no live voltage present, reducing the risk of electric shock, short circuits, or equipment damage during testing.

By ensuring that the power is off, the technician can safely conduct tests, perform checks, and make adjustments to the transformer without the danger of inadvertent energization. This practice is foundational for maintaining a safe work environment when dealing with high-voltage equipment.

While wearing insulated gloves is a common safety practice, it is not sufficient on its own if the transformer is still energized. Increasing the voltage supply or using a backup power source would both pose safety risks rather than enhancing safety. Thus, disconnecting the power supply is the critical first step in ensuring a safe testing environment for transformers.