Positive or negative to switch

[Beerdrinker]

It might sound silly but I have a question and I can't find a satisfying answer for it.
I will add an extra headlight because I run lot of kilometers at night. I will also add a switch especific to this light. Now, what should I connect in the switch, the positive or the negative wire? And why?
In my old motorcycle, the same instalation, I had the positive wire, but is this the correct?

P.S. the switch is connected to a relay connected to the ignition and with fuse also.

Thank you!:thumbup:

 

[tejkowskit]

Technically either will work, but + is more common. It just simplifies things when everything is switched the same, and everything will be at ground when the switch is turned off. And as you mentioned: put your fuse on the positive wire.

 

[fb40dash5]

I always switch the positive when possible, for simplicity and uniformity, and also because having it switched means it can only blow the fuse from a fault past the switch/relay when it's turned on. Makes it easier to run several things off a single main fuse, if something develops a short, you just don't use it until you get it fixed.

 

[DeepBlueRider]

Most bikes nowadays are negative-grounded (battery negative terminal is connected to chassis). But there used to be some with positive terminal on chassis (don't ask me why).

You should put switch on the wire which is not grounded. So as FZ6 is negative grounded, you should put switch on positive wire. Reason behind that is you don't want to be able to close circuit by bypassing switch. If you would hardwire positive terminal and put switch on negative, you could enable circuit by touching other terminal to chassis (making switch useless).