This paper describes the activities of installation and commissioning of the magnetic diagnostic enhancement for JET. The new system includes four sub-sets of probes located in the vessel in two opposite octants, for a total of 48 magnetic pick-up coils. The main goal of this enhancement is to improve the accuracy of the reconstruction of the plasma equilibrium and the performance of the real time feedback control of the plasma shape. After a brief description of the system, the paper focuses on the installation activities, accomplished during the 2007 shutdown using the JET remote handling system. The paper then concentrates on the analysis and interpretation of the data collected during the functional commissioning of the new system, carried out during the restart phase of the machine and the first part of the 2008 experimental campaigns, which proved the accuracy of the new signals and the achievement of the project goals.