What will a speed wire device accept?

The correct choice is based on the specifications and design of speed wire devices, which are typically intended for use with specific gauge wires that can optimize their performance and ensure safe connections. Specifically, speed wire devices often accept 14 AWG solid copper conductors as this gauge provides a balance between conductivity and ease of handling, making it suitable for the device's electrical connections.

Using 14 AWG solid copper conductors allows for adequate current carrying capacity while ensuring that the wires fit uniformly within the connectors of the speed wire device. This gauge also aligns with many common residential and commercial electrical systems, promoting compatibility with standard wiring practices.

In contrast, other options such as 15 AWG solid copper conductors, standard PVC conductors, or multi-strand aluminum do not meet the specific requirements or optimal operation characteristics specified for these devices, leading to potential issues in terms of fitting, connection reliability, and overall electrical performance.