Square D is a well-known brand of electrical equipment, primarily focused on circuit protection and electrical distribution products. The company was founded in 1902 by Bryson Dexter Horton and James B. McCarthy in Detroit, Michigan, under the name McBride Manufacturing Company. The company initially manufactured a variety of electrical products, such as conduit boxes, switches, and porcelain insulators.

In 1903, the company designed and patented a new type of safety switch, which was enclosed in a square-shaped box. This innovation led to the company's name change to "Square D" in 1917. The square box design became the industry standard for electrical switches and earned Square D a strong reputation for safety and reliability.

Throughout the 20th century, Square D expanded its product range to include electrical panels, motor control centers, transformers, and other electrical distribution and control equipment. The company continued to innovate in the electrical industry, introducing various new products and technologies, such as the first circuit breaker with a magnetic trip mechanism in 1923.

In 1991, Square D was acquired by Schneider Electric, a global leader in energy management and automation solutions. Since the acquisition, the Square D brand has become an integral part of Schneider Electric's product portfolio, focusing on the North American market. The combination of Schneider Electric and Square D has allowed the company to provide a comprehensive range of electrical solutions to residential, commercial, and industrial customers.

Today, Square D continues to be recognized for its high-quality electrical products, ranging from circuit breakers and load centers to safety switches and transformers. With a strong focus on safety, reliability, and innovation, Square D remains an influential player in the electrical industry.