  Let (M,g) be a compact manifold of dimension n greater or equals to 3. We
suppose that g is a given metric in a precised Sobolev space and there is a
point P in M and d>o such that g is smooth on the ball B(P,d). We define the
second Yamabe invariant with singularities a the minimum of the second
eigenvalue of the singular Yamabe operator over a generalized class of
conformal metrics to g and of volume 1. We show that this operator is attained
by a generalized metric, we deduce nodal solutions to a Yamabe type equation
with singularities.
