A 6-gauge wire is typically used for ground connections, but for buildings with higher electrical loads, larger ones are sometimes needed. Most electrical contractors prefer to use Romex brand wires.
Ground wires are available in different materials, but the best material for this purpose is copper. Most copper wires are marked "CU." Wires are identified by various marks called NEC codes, or National Electric Codes. Wire sizes are established by the American Wire Gauge system, or AWG. Ground wiring is usually indicated with a letter "G." Different types of wire are available, depending on the environment they are installed in. For high-heat and wet environments, a Thermoplastic Heat and Water Resistant Nylon Coated wire, or THWN wire, can be used.
The ground wire, also called the grounding electrode conductor, links the ground rod to the service ground connection. Everything made of metal that is connected to the electrical system, including devices, electrical boxes and wiring should be grounded. Before beginning a wiring project, acquire the necessary permits and approvals, and check local wiring codes. Most residential wiring projects require a permit and a city inspection. Wiring and cables are sold at hardware stores, electrical supply outlets and home improvement stores. Lower-priced wiring can be found online at retail websites such as eBay and Amazon.