Electronics, Lighting, & Gadgets - wire ground? dyno help.

Hello. Working on a weekend bike project...and I have no experience with electronics.

I have a SON hub, eDelux front light, and a B&M Securelite rear light. The eDelux will be mounted to a steel rack via an aluminum bracket; the Securelite will be mounted to aluminum fenders. I understand how to connect the front light to the hub, but I do not understand how to wire the rear light.

The Securelite has two plugs. One is marked earth and the other power. I assume I run the wire from the power plug to the corresponding plug on the eDelux. But what bout the ground/earth plug? Do I run another wire from the earth plug (with the ground connector thing attached on the other end) and bolt it down somewhere on my bicycle? I could sandwich the ground connector between the light and the bracket/rack, correct?

Do I even need a ground with this setup? Would it be a good idea to go ahead and do it?

Thank you.

Take a look at this link. http://www.koga-signature.com/docs/LED-Headlight_Edelux_English.pdf. It might be useful. It reads like the Power line of the tail light connects to the power switch on the eDelux, and the ground wire connects to the frame. This makes sense if the hub dynamo was also grounded to the frame. I'm not familiar with this setup, but that's how vehicle lights are wired on older cars. The negative side of the alternator and battery are grounded to the vehicle frame. A single power/positive wire to the light was all that was needed because the light was grounded to the frame.

always best to run a second wire from the ground output of the light (or dyno) to the taillight. Using the frame and other parts for ground is a lot more work. You need a ground. It's a misnomer to call it a ground in this case, it's better to call it a 'return' because it completes the circuit.