Why is there an extra wire coming off the bathroom vanity than there is coming out of my wall?

Question

Why is there an extra wire coming off the bathroom vanity than there is coming out of my wall?

Answer 1

how many wires are coming off the vanity?? and how many out of the wall??  and what color are all the wires??  if the "extra" vanity wire is copper and does not have a plastic coating then that is in fact the ground wire. If the extra wire is coated black or white, it may be for another switch or outlet on the vanity but there's not enough info in your question to tell....  

Answer 2

If this is a vanity light fixture,it is a ground wire.

Newer wiring has 3 wires- a hot wire to supply electricity,a neutral wire to complete the electrical circuit and a ground wire for safety reasons.

Older homes had 2 wires and the plugs could be inserted either way.

The the polarized plug was introduced,which meant that a plug could be inserted only 1 way (1 prong is bigger than the other).

Updated building codes are now requiring the newer 3 prong outlets,but the polarized plugs will still work in them.