Obvious question.........When you wire a bulb in for basic light with an on off switch on neg earth system..two things. is bottom of bulb pos or neg , and do the two switch connections go to pos or neg on the bulb?
Alex the Dyslexic Sparky

Assuming your talking about a single filament lamp, then the centre nipple is the positive connection, and the metal surround is the neg. The switch should break the live, (pos.), connection. HTH ATB Ray

Thanks mate.
Alex