Open class 2 transformers can be purchased with, or later paired with a protective device like a circuit breaker or fuse, unlike enclosed class 2 transformers which cannot be customized. These transformers are suitable for use on digital controllers, gas controls, ignition systems, motor actuators, staging controls, and most other HVAC and refrigeration control systems.

Enclosed and panel mounted class 2 transformers have fully enclosed, finger-safe terminals and are generally installed as-is without customization compared to class 2 transformers. They are suitable for fixed installation in enclosures, walls, or panels. Applications include building automation panels, industrial enclosures, or other general-purpose electrical enclosures.