n00b help!!!

I'm wiring up a single 55w auxiliary reverse light with a switch in the cab and could really use you guys' help

A few questions:

is 16 gauge wire ok for 1 55w lamp?
is there a difference between grounding to metal or grounding to the neg battery terminal?
is a relay necessary?

Thanks for the help!!!!!
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People are going to talk shit on my answer.

16 gauge is perfectly fine

Wiring to the chassis is perfectly fine


(here comes the shit talking part) a relay is NOT necessary. Positive wire from the light to your switch, then another wire from the switch to your positive battery terminal WITH A FUSE ON IT as close to the battery as possible

 

Cool, thanks for the response! I'm not trying to catch my truck on fire.

What Amp fuse should I use? 5? 55w/12v = 4.9 or so... so I figure 5 should be ok but i'm not positive.