As I said, I don't really know how Faraday Cages work. Forks are metal. If metal inherently protects you from electricity, then sticking a fork in a light socket should be perfectly safe. It is not. Therefore, metal does not inherently protect you from electricity.
The difference here is where the metal is located. Sticking a fork in a light socket creates a highly conductive bridge between you and the power in the socket, and that power wants to reach the ground. It travels through the fork and then into you to reach the ground as your body provides the only bridge past the fork.
If you were to wear a suit of armor, including gauntlet, and then stick a fork in the light socket, the charge would travel along the outside of the armor into the ground, leaving your body alone.
