Based upon the way you phrased the question I would assume that you are very unexperianced with electrical theory,protocall, and safety. The first thing is DO NOT, DO NOT go into the electrical panel !!!! Leave that testing to a professional !! What is the rating of your meter AND test leads ?? It should be a minimum of 600 volts. Anything less is not safe !! The small, cheap meters are of limited value and can be dangerous... If you have a plug-in 220 Volt air conditioner (large window unit) you can test it at the receptical. It has 3 pins(phase 1, phase 2, ground) -or- 4 pins (phase 1, phase 2, neutral, ground [center pin] . A test light tells you very little except for voltage being present.