In order to perform magnetic field immunity testing with levels up to 4000 A/m in direct current (as required by the latest standards) it is necessary to select the proper Helmholtz coil. In particular, it is important to choose a device with a good coil factor1 . This is possible by using an Helmholtz coil with the highest number of turns possible. In this way, high field strengths can be achieved and the current circulating in the coil can be significantly reduced. Possible candidates for DC testing are the Schwarzbeck´s Helmholtz coils HHS 5210-100, HHS 5206-132, HHS 5202- 81, HHS 5201-98, FESP 5133-1330 etc