Where do I bring the foil/braid shield? Common ground on the Arduino?
In this case I would not connect it. Don't expect very accurate readings if the cable is longer than about 2-3 meters. Try to bring the Arduino as near as possible to the sensors.
It's not unshielded, the shield is just not earthed. If you connect the shield to the Arduino's GND you can expect bigger inaccuracies than without a shield connection. If you have the possibility to earth separately, do it. You didn't tell us that you can do that.