National Electrical Installation Standards

Standards as High as Your Own

Wednesday, January 30, 2019


Hi Charlie, is there any rule about stranded vs solid thhn and lug nuts? I constantly find lugs with stranded wire jammed in and was once told they are only for solid and to use a crimp on terminal to connect

Christopher Walters



Hey Christopher thanks for your question. "Lug nuts" is a term commonly used to describe the fasteners used to secure wheels to vehicles so I am not completely sure which specific type of electric termination you are refereeing to.

Pressure connectors (lugs) and terminals must generally be Identified (as that term is defined in Article 100) for the specific type of conductor they are intended to be used with, as stated in 110.14. Detailed information should be included with the manufacturer's instructions. Wire binding screws, or studs and nuts, with upturned lugs or the equivalent are allowed for 10 AWG and smaller conductors as stated in 110.14(A).

More information about markings for solid and stranded conductors and other details is available at:

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