B & S Gauge, or Brown and Sharpe Gauge, is a standardized system used to denote the diameter of copper conductors. It is functionally identical to AWG (American Wire Gauge).
B & S Gauge, short for Brown and Sharpe Gauge, is an older term still occasionally used in the wire and cable industry to refer to wire sizes. This system originated from the Brown and Sharpe Manufacturing Company in the 19th century and became widely adopted in North America for specifying the diameter of nonferrous wire, primarily copper. Today, B & S Gauge is interchangeable with AWG, which is the more common terminology. Both systems follow an inverse relationship between gauge number and conductor diameter, standardizing selection for electrical and signal applications. Although considered a legacy term, B & S Gauge still appears in older documentation and specifications, and understanding its equivalence to AWG avoids confusion in technical contexts.
Referenced in standards by UL (Underwriters Laboratories), NEC (National Electrical Code), and IEEE (Institute of Electrical and Electronics Engineers).
The Brown and Sharpe Gauge was introduced in the mid-1800s as a more accurate alternative to inconsistent sizing methods of the time. It became the foundation of the American Wire Gauge system, which remains the U.S. standard for measuring nonferrous wire diameters.