I live in a Chicago bungalow, built in 1926. The electrical service is grounded via a water pipe. When installing a 20amp 220v outlet, there are two brass terminals and a green ground. Should the the green grounding terminal be wired to the neutral bar, or grounded to the box. If I were to use a 20 amp 110v outlet there would be a brass and a silver terminal, as well as a green ground. Why is there no neutral terminal on the 220v outlet
If this is the main panel then the neutral and ground bars are the same thing. You can connect to either.
If this is a sub-panel then the ground goes to the ground bar.
There is no neutral because there is NO neutral on a 220 volt circuit, simple as that. Two hots and ground.
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC. If you're on the '14 already I feel sorry for you.