We demonstrate that two mechanisms of lamellae reorientation observed experimentally under applied electric field [A. Böker H. Elbs, H. Hänsel, A. Knoll, S. Ludwigs, H. Zettl, V. Urban, V. Abetz, A. H. E. Müller and G. Krausch, Phys. Rev. Lett., 2002, 89, 135502] which have been previously described within dynamic self consistent field theory [A. V. Zvelindovsky and G. J. A. Sevink, Phys. Rev. Lett., 2003, 90, 049601] can be fully explained within a much more simple model using the Ginzburg–Landau Hamiltonian. A third alignment mechanism has been identified which was not previously reported. A more complete picture of reorientation under electric field emerges that clarifies the crucial role of structural defects.