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Adding Equipment To Positive Earth Cars


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#1 Minigman

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Posted 07 November 2019 - 08:46 PM

I have a 1960 mini which retains positive earth. If I want to add a front driving lamp how is this done?

Do I take a 12V feed from off body work and then utilise the switched 0V neg from the high beam? I assume a relay won’t work in this scenario.

I have no issues with wiring neg earth but can’t get my head around positive so any help would be appreciated.

Maybe I’m being thick!

#2 nicklouse

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Posted 07 November 2019 - 09:01 PM

just wire as normal.



#3 unburntfuelinthemorning

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Posted 07 November 2019 - 09:07 PM

You wire it the same way as the polarity doesn't matter in this instance as conventional bulbs aren't polarity sensitive.  If you wanted to fit a modern stereo you'd have more difficulty.



#4 Minigman

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Posted 08 November 2019 - 11:00 AM

on a neg earth system - normally id take a 12v feed from the fuse box via a relay which is switched by the high beam wire, and then ground to the bodywork.

 

on a positive earth system  - as all the switching is done via the 0v neg i cant do that here?

 

so do i just take a feed from anywhere on the body work, inline fuse it, forget the relay and splice into the high beam switched neg via a dash switch?


Edited by Minigman, 08 November 2019 - 11:08 AM.


#5 Minigman

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Posted 08 November 2019 - 11:04 AM

You wire it the same way as the polarity doesn't matter in this instance as conventional bulbs aren't polarity sensitive.  If you wanted to fit a modern stereo you'd have more difficulty.

 

did that by running a new feed from the battery in a neg earth arrangement. so long as nothing conductive touches the body work it seems the easiest way to go. Just cant get my head around this positive earth system. 



#6 unburntfuelinthemorning

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Posted 08 November 2019 - 02:18 PM

You're over thinking it, the polarity doesn't matter for what you're trying to do. 

 

You can pretend it's a negative earth system for this job and wire accordingly.

 

Another way of thinking is forget about voltages.  If you only had a test light and no knowledge of positive or negative earth how would you go about wiring it?  Do it like that.

 

As you can see in the photo below everything is wired the same whichever way round the battery is connected.

 

jPMBEUo.jpg



#7 Minigman

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Posted 08 November 2019 - 08:49 PM

Thanks.

Got it now.




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