There is no simple answer to the length of a drive distance for encoders. Dynapar offers many feature options for encoders. If one simply uses high grade Teflon coated cable instead of PVC, the capacitance decreases from 37pF/Ft to ~12pF/Ft, tripling the useful drive distance. This variation in drive distance is solely based on the type of connection wire implemented

For single drive distance, you should consider a number of factors other than wire type. It is important to have the lowest possible cable capacitance and pulse frequency. A moderate level of voltage is best. You can even compromise with 12-15 volts when needed. Too much voltage leads to excess heating to drive current while too little causes a voltage drop at other end. Also, consider the drive current capability of the output circuit and thermal capacity of the encoder when drive distance is a concern.