Uninsulated exposed parts in Class II locations must operate at voltages not exceeding what amount?

In Class II locations, which are typically associated with the presence of combustible dust, it is crucial to maintain stringent control over electrical equipment and their operating conditions to minimize the risk of ignition. Uninsulated exposed parts of electrical equipment in these environments are limited to a maximum operating voltage of 30 volts. This is in line with safety standards which prioritize reducing the potential for ignition sources, as even small amounts of energy can be enough to cause a spark or heat sufficient to ignite combustible dust particles.

Maintaining an upper limit of 30V helps to ensure that any unintended contact with these parts does not result in dangerous currents that could lead to sparks. This standard reflects an understanding of the hazardous nature of dust environments and the best practices in electrical safety that aim to prevent accidents in the workplace.

The other voltages listed exceed this safety threshold and would pose a higher risk in a Class II environment where even low-energy ignition sources can lead to significant hazards.