Extend I2C communication distance with this app note (PDF) from NXP.
Reliable I2C-bus communication at high data rates, and over many meters, can be achieved using widely available twisted- pair communication cable (e.g. Category 5e and similar 4-pair cables, as typically used for Ethernet communications).
The two bidirectional I2C-bus signals, SDA and SCL, are split into four unidirectional signals using P82B96 or PCA9600. Each signal is then transmitted over a separate twisted pair within the communication cable and combined again by another P82B96.