What type of fastening device is not appropriate as a handle tie for two breakers?

The choice of a nail as a fastening device for tying two breakers together is not appropriate primarily because nails are not designed to securely hold electrical components under the conditions found in electrical panels. In the context of electrical work, it’s crucial to use fastening devices that provide stable and reliable connections without risking disconnection due to vibration, heat, or other factors that can occur during operation.

Screws, wire, and clamps are typically more reliable for this application. Screws provide a strong and secure hold, wire can be used effectively to tie breakers together while ensuring proper electrical continuity, and clamps offer the ability to maintain a firm grip under various conditions without damaging the equipment. These options ensure that the breakers function as intended and reduce the chances of failures or hazards in the electrical system.