My distro's tor setup (arch in this case) should default to not being an exit node, relevant default lines in the torrc:

  ExitPolicy accept *:6660-6667,reject *:* # allow irc ports but no more
  ExitPolicy accept *:119 # accept nntp as well as default exit policy
  ExitPolicy reject *:* # no exits allowed

Installing via `pacman -S tor` and enabling via `systemctl enable tor.service` doesn't start an exit node / relay but a simple client.

Are you using linux, windows or osx?