Sorry- totally forgot about this
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I'm guessing your diagram looks something like this?
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![Image](http://i354.photobucket.com/albums/r420/fomoashman333/BatteryMasterSwitch_zpsc3a87fd0.jpg)
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Seems fairly straight forwards:
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You connect the large poles between battery positive and and the main
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+'ve car harness; this circuit is normally closed, and so the car electrics have a
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+'ve feed.
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You then need to cut the ignition/ switched live feed to the coil and reconnect this across the two
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"2" poles.
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This circuit is normally closed, and so the coil will have
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+'ve feed for ignition.
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You then run a wire from the main
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+'ve car harness to one of the
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"1" poles, and the other
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"1" pole connects to the resistor, and the other side of the resistor you connect to earth.
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This circuit is normally open, and so the resistor is not connected.
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When you activate the cut off switch it breaks the main
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+'ve feed to the car electrics.
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It also breaks the
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+'ve feed to the coil, and so cuts ignition and in turns prevents the engine running on
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(powered by the alternator).
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Finally this also grounds the main
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+'ve car harness across the resistor, presumably to prevent any large voltage spikes from damaging other components
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(I'm guessing on that score!).
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I imagine that the resistor will get quite warm when you use the cut off switch
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(at least for a little while), so probably an idea to mount it away from other components and wires.
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That's my best take on it anyway, if I was you I would double check with someone who has wired one in before to be sure, the last thing you want to do is have a switch that doesn't actually cut off when you need it most
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