Do you turn on the shower and feel an occasional buzz or shock through the faucet? You may have a corroded joint or bad neutral that could be affecting your plumbing.
At the rough-in time, it is important to run pipes with enough volume and pressure so that many fixtures can be used at the same time. Another nice item that is plumbing code in many areas now, is the pressure-balanced tub and shower valves. A single handle valve that balances the hot and cold water to try to maintain a temperature range plus or minus 2 degrees.