I'm replacing the ground wire in a chandelier because it has been cut by the previous owner when it was removed from the ceiling. Overall it is pretty simple and I have everything diagramed. When I went to Radio Shack and bought the replacement wire they gave me 18 gauge solid insulated hookup wire. It looks totally different. The ground wire is a braided copper wire (7 strands). Should I go back and take my copper wire with me and get copper or is what I have just as good? An electrician will do the installation of the chandelier into the ceiling.
The reason they use copper as it does not corrode...
Radio Shack's hookup wire is copper, but it may be tinned so it has a silver/chrome color instead of a copper color. Tinned wire is more expensive but is also more resistant to corrosion. Braided wire is more flexible than solid wire, but either will do the job. The only real important consideration is the gauge of the wire. You want to make sure your new ground wire is at least as thick as the old one.
Ground wire is common convention at electrical boxes. Ground wire from point to point in any circuit is part of the wiring cable used. On a ceiling light, there is little danger of electrical shock if there is no ground wire from the fixture to the metal box. However, your replacement wire will work just fine.