Based on some new ideas, the 35 MV vivitron tandem is being presented and is now in the first year of construction at Strasbourg. This tandem is a horizontal machine supported from the tank wall by means of discrete electrodes alternating with post insulators. The general features as well as insulator and conductor designs are described. The machine is designed to minimize energy dissipation within the accelerator column, in the event of electrical breakdown. Details and results are given about tests performed for vivitron components in different Van de Graaff machines.