For high-flexibility motor leads, engineers typically avoid solid conductors because:

• A. They are too expensive
• B. They cannot be insulated
• C. They lack flexibility
• D. They have higher inductance

Answer: (C)

Repeating bending and movement require a conductor that can flex without fatigue. A solid conductor is stiff and resists bending, so when the lead is flexed many times, the stress concentrates at the bend and the metal can fatigue, eventually cracking the conductor or breaking the insulation. Using stranded conductors distributes the bending stress across many small wires, so the lead remains flexible and durable through many flex cycles. The insulation can still be applied around the stranded bundle to maintain electrical isolation while preserving flexibility. Other factors like insulation capability or cost aren’t the primary reason here, and inductance differences between solid and stranded conductors are not the main concern for high-flexibility motor leads.