What is the limitation for knife switches rated for over 1200 amps at 250 volts or less?

Knife switches rated for over 1200 amps at 250 volts or less have specific limitations regarding their use to ensure safety and compliance with electrical standards. The correct choice indicates that these switches can only be used as isolating switches and must not be operated under load. This restriction is primarily for safety reasons; while knife switches are designed to control electrical circuits, when operating at high current levels, they can pose significant hazards if switched under load.

Using these switches solely for isolation prevents dangerous arcing or electrical failures that could occur if they are misused. This practice ensures that maintenance can be carried out safely, as the circuit can be safely de-energized before the switch is manipulated. Adhering to this limitation reflects best practices within the electrical industry, promoting both user safety and equipment integrity.