Coleman Cable 18-1-17 Automotive Copper Wire, 18-Gauge, 33-Foot, White. Coil of bare copper wire is great for wiring cars, boats, and more. PVC outer jacket resists water, oil, chemicals, and abrasion. Coleman Cable is an Industry leader in Copper Wire, offer multiple lengths, thickness, gauge, color. 18-Gauge White wire with 0.092-Inch Outside Diameter, 33-Foot Length. Copper Wire - for low voltage wiring in surface vehicle electrical systems. Copper wire is commonly known in the automotive industry as Primary Wire. It is mostly commonly used in electrical systems of cars, boats, and other vehicle electrical systems with 60 DC-Volt (25 AC-Volt) or less. It is also passes SAE standards.