General Electrics

[nicademus]

I am confused with making a new circuit in my car. Should i wire it from positive then back to the negative terminal on the terminal or straight to earth?

[tigga]

You will have to be a bit more detailed and im sure we can then help.

[KebabMeister]

Earth is negative so just put the negative wire to a suitable earth point. If you are making a circuit then ensure you fuse the live wire!!!!

You can either make a permanent live wire or an ignition live (wire is negative with ignition off, but once ignition switched on it becomes live). It obviously depends on what you need the wiring for.

[kempie]

...of course KM has based his answer on the car not having a positive earth.

[KebabMeister]

Which cars have postive earths? They stopped having postive earths because the electron flow caused increased corrosion. I guess you could have a positive earth if it's a plastic car?

[JudgeJ]

Older cars with generators rather than the more modern alternators had positive earth. Alternators replaced generators on a widespread basis probably in the mid 1970s (though I couldn't be sure of that date).

[KebabMeister]

True, I guess there are some classic cars that are still using Positive earth although most are converted to Negative earth. Incidently, a Generator could be polarised to be used for negative earth.

So, nicademus, we should be asking what car you have and what is it's age?

[Andy Boz]

Surely if it's a plastic car then it doesn't have an earth as such, all the electrical devices have to have a return, but not through the earth.

To the original question, what circuit are you trying to fit, to which car? More to the point, I would respectfully suggest that if you are not 100% sure of what you are doing, either get it done professionally, or better still, get somebody to do it whilst you watch and learn.

Scrapyards are full of cars that have been burned out by dodgy wiring.

If you are going to do it yourself, assuming the -ve on the battery goes to the body of the car, then you can either wire the return to the body, having first scraped off paint, or if it is a large current device, then you are better going back to the terminal itself.

Hope this helps

[Jay70]

Just out of interest i think some MG B's and the Morris Minor had a positive earth.

[kempie]

MG produced +ve earth MGAs, Bs, Midgets until the late 1960s.

My original point was that we should follow tigga's suggestion and not assume anything about the car in question, especially when electrics are involved.