When type NM cable is run at angles with joists in unfinished basements, what is the minimum size of conductors that can be secured directly to the lower edges of the joists?

The minimum size of conductors that can be secured directly to the lower edges of joists when running type NM cable at angles in unfinished basements is indeed #6 and #8. This requirement is based on the National Electrical Code (NEC) guidelines regarding conductor size and securing methods, which ensure safety and minimize the risks associated with overcurrent and overheating.

Using #6 and #8 gauge conductors provides sufficient ampacity for typical residential circuits while also allowing for proper installation practices. The use of these specific sizes ensures that the conductors can safely carry the electrical load without overheating, especially when installed along joists where they may be subject to heat retention.

In contrast, smaller conductor sizes, such as #8/#10 or #10/#12, may not provide adequate protection or may not meet the ampacity ratings required for various electrical applications. Using conductors that are too small can lead to safety hazards, including the risk of overheating and potential fire. Therefore, the choice of #6 and #8 is both practical and consistent with electrical safety standards.