Solid is one wire. Stranded is many small wires bundled together. The connector has to suit which one you have.
Stranded conductor in a terminal meant for solid can leave strands outside the clamp, and a connection carrying only part of its conductor is a hot spot you have built and then closed a cover over.
Two conductors can be the same size and still need different terminations, because the way the terminal grips them is different. A clamp that bites one solid wire cleanly may not gather every strand of a stranded conductor of the same size, and the strands that miss the clamp are not carrying current -- which means the ones that did are carrying more than they were sized for.
Check yourself: A terminal accepts a solid conductor of a given size. Will it accept a stranded conductor of the same size?
Answer: Not necessarily. A terminal acceptable for one conductor type may not accept another.
Size and construction are two separate requirements. The terminal is rated for both, and matching only the size leaves the second one unchecked.
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Written from the owner's poster for this lesson. Nothing added beyond what the poster states.
Written for Texas apprentices as free study material. The Texas apprentice licence is an application, not an exam (Occupations Code 1305.161), and nothing here counts as apprenticeship hours or continuing-education credit. VoltMark is not affiliated with, endorsed by, or sponsored by NFPA, PSI, TDLR, or any state or local licensing authority. Always follow your employer's safety programme and your supervising electrician.
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