I have connected four pot lights running on the same wire from the panel and then to the switch after the fixtures themselves. They turn on fine but when I turn the sw. to the off position, it trips the breaker. What is wrong? Please.

Barb

You will have to tell us how you wired them before we can tell you what you did wrong.

If the switch is on the opposite side of the lights from the power, you need to use a switch loop circuit instead of the hot freed through the switch. As Harold indicated, tell us how you have it wired.