It is not recommended to exceed 125ft between thermostats. For XBus systems, each CAT5 cable run can be no longer than 1,000ft total with no more than 8 thermostats on a single CAT5 cable run. It is highly recommended to use an NT-TB terminal board as a hub for your XBus thermostat cabling. Each 'drive' (X1/X2) on a network controller can support up to 2,000ft and a maximum of 16 thermostats. With each controller having two drives, up to 32 thermostats can be supported on up to 4,000ft of CAT5 cable.