The Finite-element method (FEM) is well suited for solving problems involving inhomogeneous and arbitrary shaped objects. Unfortunately, for large-scale problems, this method yields a huge coefficient matrix system whose inversion may be time and memory consuming. Many techniques have been reported to increase the computational efficiency. Among them, the domain decomposition-based methods are especially appealing and in particular, the dual-primal finite element tearing and interconnecting method (FETI-DP) has been recognized as one of the most scalable parallel solver in computational mechanics and acoustics. Over the past years, it has also been successfully applied to the simulation of two- and three-dimensional (2D and 3D) large-scale electromagnetic (EM) problems (J.-M. Jin and D. J. Riley, IEEE, 2009).