  We propose a phenomenological theory for topological crystalline insulators
with time reversal and $C_4$ symmetries. First, we introduce a fictitious space
and transformation of electromagnetic field operators. This transformation
leaves the speed of light unchanged but changes the elementary charge to
$\sqrt{2}e$. Then we formulate the theory of topological crystalline insulators
in terms of transformed fields in this fictitious space as 3D BF theory
containing $\pi$-flux excitations. It is known that a 3D BF theory with half
flux quantum excitations describes low energy properties of time reversal
invariant insulators. By making an inverse transform we recover the effective
field theory in original space. It turns out that this field theory contains
quarter flux quantum excitations.
