We recommend that any cable alterations be made before the unit has been calibrated, as the small changes in resistance of the cable can cause errors. Please note, any cable alterations may affect the lead time of the sensor. A maximum of 20m cable length is advisable on any device without sense wires. If we are not carrying out the cable alteration it is necessary that you use a screened cable for any extension. Any cable alterations may effect the product warranty.