The placement of the sensors is really at the customers discretion. In a perfect world there would be a sensor everywhere water could be leaking but that may not be practical. The actual sensors should be placed slightly off the floor in most situations so that a damp floor or condensation does not cause a [...]
Yes this is possible, if there is a strong radio transmitter near the DA500CP or lots of radio and cellular activity around the unit it is possible that the activity can trigger false alarms.
The maximum recommended cable length is 195 feet. Each camera in the systems comes with 65 feet of cable so you could add the 130 foot extension cable to each of those.
Yes it does.