It’s important to follow important safety guidelines before installing or even purchasing that new ceiling fan. First, you’ll probably need to change the electrical a bit. A ceiling fan can weigh more than 20-30 pounds, and thus will require a sturdier junction box (where the electrical is provided). The proper junction box will also compensate for the increase in the spinning motion. Replacing the light fixture with a ceiling fan is a safety hazard. Also obviously you’ll want to be sure the fan does not hang low enough to hit anything or anyone while spinning!