Headlamp Shell Earthing

[Nourish]

Why does (usually) a headlamp shell have a earthing point?

[bsa-bill]

Possibly --- because the earth is normally via the bike frame meaning it has to track through grease filled bearings (which it does fairly effectively) but many (me included) like to run an earth wire front to back for a more reliable earth

[A10 JWO]

Even the Japanese cousins do that and Italian Scooters.

[Swarfcut]

    Could be a one size fits all, and Old Joe Lucas found it cheaper to make all shells electrically the same.  There would be need for some guaranteed earth return for pilot bulbs on rubber mounted speedos, rather than the grease filled cable, so having some central earthing point makes sense, and  an Earth connection from lampholder to headlamp shell and then to frame via grease filled headstock bearings was the way it was done.  Your own earth wire is a worthwhile improvement, as noted.

 Swarfy

[Triton Thrasher]

So any electrical components mounted in the headlight can be earthed to the shell.

Obviously, we connect the shell to the battery return pole with an actual wire.

[Slymo]

I think people who have an issue with 6v systems have often failed to properly earth the various parts of the bike. I generally make my own looms and have a good substanial earth wire running to all points from tail to head and inbetween. Its very important at the headlight as failure to do so can result in the spark erosion of the headrace bearings.