How can restricted access be defined regarding adjustable-trip circuit breakers?

Restricted access in the context of adjustable-trip circuit breakers is best defined by the implementation of removable and sealable covers over the adjusting means. This design ensures that only authorized personnel can make adjustments to the breaker settings, thereby preventing unauthorized modifications, which could lead to unsafe operating conditions or equipment damage.

By using removable and sealable covers, a manufacturer ensures that the settings remain untouched unless someone with the proper authority has the tools and permission to make changes. This enhances safety and compliance with electrical regulations, as it minimizes the risk of accidental tripping or improper function due to erroneous adjustments.

In contrast, while glass viewing panels may provide visibility into the operation of the circuit breakers, they do not restrict access to the adjusting mechanisms. Simple magnetic locks or unsecured access panels do not provide adequate security and can easily be tampered with, allowing unauthorized individuals to change the settings without proper oversight. Thus, the use of removable and sealable covers is the most effective method for defining restricted access to an adjustable-trip circuit breaker.