We discuss the relation between particle number conservation and topological phases. In four spatial dimensions, we find that systems belonging to different topological phases in the presence of a U(1) charge conservation can be connected adiabatically, i.e., without closing the gap, upon intermediately breaking this local symmetry by a superconducting term. The time reversal preserving topological insulator states in 2D and 3D which can be obtained from the 4D parent state by dimensional reduction inherit this protection by charge conservation. Hence, all topological insulators can be adiabatically connected to a trivial insulating state without breaking time reversal symmetry, provided an intermediate superconducting term is allowed during the adiabatic deformation. Conversely, in one spatial dimension, non-symmetry-protected topological phases occur only in systems that break U(1) charge conservation. These results can intuitively be understood by considering a natural embedding of the classifying spaces of charge conserving Hamiltonians into the corresponding Bogoliubov de Gennes classes.Introduction -In recent years, topological states of matter (TSM) that can be understood at the level of quadratic model Hamiltonians have become a major focus of condensed matter physics [1][2][3][4]. An exhaustive classification of all possible TSM in the ten AltlandZirnbauer symmetry classes [5] of insulators and mean field superconductors has been achieved by different means in Refs. [1,6,7]. For the symmetry class A of the quantum Hall effect in 2D, i.e., no symmetries except a local U(1) charge conservation, there is a variety of topological phases apart from the integer quantum Hall (IQH) phases [8][9][10], namely the family of fractional quantum Hall states [11][12][13] that exist only in the presence of interactions and hence cannot be adiabatically deformed into non-interacting band structures. These phases can be classified in the framework of topological order which was introduced by Wen back in 1990 [14]. In a more recent paper by Chen, Gu, and Wen [15], it has been shown that different gapped phases which do not have local order parameters associated with spontaneous symmetry breaking must have different topological orders. Furthermore, Ref.[15] identifies different topological orders with different patterns of long range entanglement (LRE).