I have project and use 10 DS18B20 sensors to connected on one cable (parasite power mode). Longest distance of 16-18 meters (2 pieces), 10-12 meters (5 units), the other 3-4 meters. Runs great. The project is here: Saulė Virė - Saulės kolektoriai, valdikliai, pasidaryk pats (and here- http://www.ksduino.org/?devices&device_id=3331) (works half the year, but the site still has not been made).