  Some of basic problems in neutrino physics such as new energy scales, the
enormous gap between neutrino masses and the lightest charged fermion mass,
possible existance of sterile neutrinos in eV mass range are studied in the
local gauge group $SU_{L}(4)\times U(1)$ for electroweak unification, which
does not contain fermions with exotic electric charges. It is shown that
neutrino mass spectrum can be decoupled from that of the other fermions.
Further normal seesaw mechanism for neutrinos, with right handed neutrino
Majorana masses to be of order $M\gg M_{\text{weak}}$ as well a new eV-scale
can be accomodated. The eV-scale seesaw may manifest itself in experiments like
Liquid Scintilation Neutrino Detector (LSND) and MiniBooNE (MB) experimental
results and future neutrino experiments.
