more diy than a hobby i guess.

is there any electricians here?
i was rewiring my upstairs lighting circuit, a simple task , i took my time as i had walls ,floors and loft boards to negotiate,
i left some of the work overnight so instead of connecting to fuse box that day, i connected to a 13 amp plug( 3amp fuse) at first i didnt bother to conect earth it being lighting, i noticed that the earth lit up my scew driver how i thought it isnt connected mmmm faulty wiring ? rolled out some more wire from new roll the same again even if i connected the earth, if i touched earth and negative with my finger while holding screw driver on earth it lit up even brighter, so i thought well it cant be faulty wiring ,,,, i know that electric leaks ,the longer the cable run seemed to be the dimmer the screwdriver was, untill not lit at all,
im a plumber by trade, iv worked with all trades but i never , heard seen,or noticed this before,

budding electricians , can you solve my puzzle , why ?