What is not considered a common defect with branch circuit cables?

The choice indicating that oversized conductors to appliances is not considered a common defect with branch circuit cables is accurate because using appropriately sized conductors for the load is an essential part of electrical installations. When conductors are sized correctly for the appliance they serve, it helps to ensure safety and efficiency. Oversized conductors are often not a defect in themselves; in fact, they may provide a margin of safety by reducing the resistance and potential overheating, although they may not always be necessary for every application.

In contrast, other options represent recognized issues within electrical systems. For example, NMC (non-metallic-clad) cable run without protection can be prone to physical damage, leading to safety hazards. Open junction boxes in attics can create fire risks and are a violation of electrical codes. Open conductor splices represent a significant safety concern as they can lead to arcing and electrical failures. Therefore, while having oversized conductors themselves may not constitute a defect, the other options clearly indicate common defects that could compromise electrical safety and code compliance.