power hid ballast through acc switch

I need some assistance, here is what I am trying to do.

I want to use a HID ballast that I have, I have a housing for the bulb, and the bulb, I want to mount it to the rear of my vehicle under neath so I can use it as a optional back up light.

I stopped by radioshack and picked up two 12v switches, I needed one for my double din display to bypass the brake switch. So I bought two so I can do what I want with the light.

I am not exactly sure how this would all be CORRECTLY done, but I feel I am pretty smart and could handle this. I just need someone to tell me everything lol. in a way

Right now, I am thinking about running some sort of gauge wire directly from the battery to switch. Then from there to the rear of the truck, this would provide the ballast with 12v, again I am not sure if this is how this would be done, so please assist me. From here the ballast would be grounded to the chassis, the switch would be grounded to the chassis as well.

Is this how it would/should be done? Are any fuses needed or anything?

Thanks

What is the amp rating of the switch you purchased. It should have a rating such as 120V/3A. What is the number before the A?

This looks like the exact switch I purchased, I am too lazy to go look in my truck exactly now.

https://www.radioshack.com/product/index.jsp?productid=3111494&retainProdsInSession=1

So it would be rated at 30 amps? Would this work? Also,what is the correct hook up.

Would HID's heat output melt plexiglass?

12Guage wire from the battery to the input terminal of the switch. Make sure you place a fuse holder fitted with a 10 amp fuse at the battery. Output terminal of the switch is to be connected to the positive wire of your ballast. Ground the ground wire of the ballast.
Ground the ground terminal of your switch.

Why is a fuse needed between the switch and the battery? I am not knowledgeable about this, mind schooling me for a second?

My amp power wire, is 4gauge I beleive and is very thick. It has a fuse holder already in place. Could I just splice my 12gauge wire in next to the 4 gauge wire after the fuse that comes from the battery?

Essentially, I would have two things drawing from the fuse.

Thoughts please?

If you connect a 12Gauge wire to a battery or to a 4Ga. wire that has a 150 amp fuse, you need to properly fuse the 12Ga. wire.  A 150 amp fuse will not protect a 12Ga. wire.  If the wire were to get accidentally grounded, it may catch fire.

Ok, so could I use 16 gauge speaker wire, i can't fine any quality 10-12 gauge wiring in my house. The 16 gauge speaker wire is very nice, its monster gold plated.

Do you have any idea how much current your HID draws?

It uses 35watts, is this what your looking for?

A 16Ga. wire will handle 15 amps of current.  Your lamps draw 3, I would fuse the 16Ga. at 10 amps.

Either way really, I am only operating the light for a short period of time, so I should be safe.

Thanks for your time, ill let you know how it all goes.

Thanks, it all went as planned, the only issue was the long labor of installing it all nicely.

Thanks for your help, I now have a HID reverse light.