vraymesh light and power

I have some problems/questions.

how is the vraymesh light calculating the power of light?
when I have a big mesh object then the light strength (luminous power) seems wrong. when I set the luminous power to 1700 (100 watts) then the default image strength is 0.035! this is much to dark… I want to get a white light especially with this camera settings for interior shots, fn 4, shutter 30, iso 300.

thanks for helping

best regards
themaxxer