Well, the subject says it all.
If I were to wire something into my cars power, and wanted to have a manual switch to turn it on and off, such as a radar detector, would I wire the switch into the ground, or to the power wire. Is one any safer, or better for the acc.?

I know that the question may be stupid to some people, but I dont want to end up with my car on fire going down HW59!
I am trying to learn how to do electrical stuff on my car, and we all got to start somewhere!

Thanks for the help,
Daniel

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92 Rs 3.1/T-5
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Good question and here is a good answer.
Just install an inline fuse from radio shack on the positive wire. Really it doesn't matter but I'd put the switch in positive just so I know that all my switchs in my car are all positive.
positive line---(fuse)---(switch)----(+
ground/negative line ----------------(-
You shouldn't catch your car on fire unless you use a penny in the fuse box literally. Don't wire it directly up to the battery either, better of wiring to the acc line which can be found going into the radio.

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, Jon (91 RS too many mods to list), getting new engine in summer

 

Thanks for the quick response!

I was planning on wiring it up through the wires that go to the overhead lighting since it will be mounted up there, but the acc would be much better. I'll just have to run some wires.
What amp fuse would you suggest?

Thanks again,
Daniel

 

yeah, i would wire to the accessory wires or something else that will be on whenever the car is on, cause you really don't have to worry about a radar detector when the car isn't even on.

 

In effect, it doesn't matter what wire you install the switch on. For instance, most domestic cars have the door pin switch on the ground, and most imports have the switch on the positive side.

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'82 Firebird, dead stock, 9 bolt disc rear, over 200,000 miles and still going strong, more to come...
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Ok,
I would guess the flow is stopped no matter which side it is on anyways. Thanks for the help so far. Any more suggestions?

Later,
Daniel

------------------
http://kiztope.50megs.com
92 Rs 3.1/T-5
KYB Shocks and Struts, Blue Streak cap and rotor, neato new radiator!, RapidFire plugs

An overhead console!!
Clarion Head Unit,
Pioneer 6x9's,Cerwin Vega Plate 4x6's
.....
Its slowly but surely coming along....

AIM : Theonekiztope
ICQ: 8787542
Planetarion: 3GFB kiztope of kiztopia-Camera-92RS-A (33:6:14(?))

"No one knows until they learn" Leon Calrinsky (99)

 

You'll have to be careful if you are installing an accessory that has a grounded case, and would get a ground directly from the chassis whwn you mount it. This wouldnt be the case with your radar detector, but might be an issue if you were mounting, say, driving lights to the frame under the bumper. Things like that you should switch the positive, and still good idea to use an inline fuse on the positive.

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82 T/A 305/TH350; soon to be 350/T-5

 

It does matter!!!!!

If you wire the switch to ground, then the item powered is "hot" all the time.

If you wire the switch to the "hot" side, then the item powered is grounded when the switch is off.


Go power to fuse to switch to electrical item to ground.

 

You should connect it on the positive side. Some things need very little gound or can find what it needs pretty much anywhere on the car but there are only a few places that carry a positive current. Thats why almost every major electrical item in your car cuts off the positive side.

 

I was actually thinking about the "hot all the time" thing myself. I will probably wire that radar detector into the system this weekend when I get some spare time.

Thanks!
Daniel

 

Depending on the accesory. When I said that it doesn't matter, I was talking about extra items. A radio, or other "case grounded" things should be broken on the power side, 'cause you can't brake 'em on the ground side.
Things like fog lights also only have one wire coming out of them, so that's where you'd put the switch.
I have an aaaauuuuuggggggaaaaa!!! horn that I added, and I wired the switch on the ground. No problems.
If you do it right, you don't have to worry about shorts so it doesn't matter if it's hot all the time. There is no completion of the circut, so no power is being used.