The authors discuss the performance of an insulating system with floating electrodes, submitted to lightning impulse tests. The performance of a four conductor compact system was analyzed, for medium voltage networks, known as "spacer systems" and the performance of medium voltage gaps. For the spacer system, among the various conductor connections, those which presented floating electrodes were discussed. Experimentally, the influence of these electrodes was verified, with large dimensions, by comparison with standard systems without floating electrodes on the basis of the value of the critical flashover voltage and mainly on the value of the standard deviation of the critical flashover voltage.