Ising lattices with +/-J exchange interactions present frustration tha
t raises the energy of the ground level as well as its degeneracy. Thi
s leads to think that after going over the states in half the configur
ation space, the different ground states will end up alternating all s
pins yielding a null site order parameter. In the present work we give
numerical results that indicate that there is always a large region i
n these lattices, which remains free of frustration in the ground stat
e. So if the ergodic separation is done in such a way as lo leave this
region with one possible spin orientation on one half the configurati
on space and the other spin orientation in the other half, it is possi
ble to define a partial spin-glass phase with a positive site order pa
rameter.