If there was nothing between the Bridge and the sensors, the distance can be as far as 40 feet / 12 meters.

But because the sensors are usually installed in electrical panels and are made of metal (an RF interfering material), we recommend installing Bridges no farther than 20 feet / 6 meters away from the sensors. 

However, the RSSI should always be the key indicator of how close/far the Bridge is installed from the sensors. An acceptable RSSI range is -30 dBm and -75 dBm.

Given this ideal range, there is also a minimum distance recommended, especially for PAN-42 meter installation as if the RSSI is too strong between the Bridge and the sensors, the data delivery will be inconsistent. Ensure the Bridge is installed at least 3 feet / 1 meter away from PAN-42 sensors.