Must I ground an exterior 110 V AC post lamp. Only two wires are available (no third ground wire)?

Question

The wire is buried under the lawn and underground sprinkler piping and runs from GFCI exterior plugs to post lamp locations (about 100 feet). The lamps use 110VAC compact fluorescents with built in ballast. The wire looks to be about 12 gauge exterior wiring.

Answer 1

the GFCI outlets  takes care of the lack of a ground wire.... just don't forget to test them occasionally....

Answer 2

They probably should have been installed with three wire cable. I would suggest driving a 3 foot copper pipe into the ground and connect a heavy wire from the pipe to the post.

Answer 3

put the ground wire from your source to the fixture itself