What action is prohibited for conductors larger than 10 AWG when connecting via studs and nuts?

The prohibition of using upturned lugs when connecting conductors larger than 10 AWG via studs and nuts is based on safety and efficiency considerations in electrical installations. Upturned lugs can lead to improper connections and increase the risk of electrical arcing or failure due to inadequate surface contact. When a lug is turned up rather than laid flat, it may not secure the conductor properly against the terminal, which can lead to overheating or electrical shorts as the connection may not withstand the necessary mechanical pressure required for larger gauge conductors.

Moreover, the use of specific types of lugs is governed by electrical codes and standards that ensure reliable connections to safeguard against potential hazards. This regulation aims to maintain integrity in wiring systems, ensuring that larger conductors are adequately connected to handle the current they are designed for without creating a fire risk or causing equipment damage.

In contrast, the other options involve practices that, while significant, do not directly relate to the more pressing safety and mechanical connection concerns posed by upturned lugs specifically for conductors larger than 10 AWG. Proper installation practices require attention to detail and adherence to codes that govern the electrical work being performed.