Sounds like there's been some confusion around the device here.
What you need to do is let us know the exact part number on that 712.
There are two basic varieties, one is a small 8 pin SOC and the other is more like a TO220 type package with 'horns' on it.
From what I gather, you have the 'horny' one.
Now, I understand you are able to get uni-directional or bi-directional sensors.
Bi-directional will have their output at Vcc÷2, while the uni-directional will be close to zero volts while no current is flowing through the main current sensing line.
Which one do you have?
These devices will take way more current than what they are calibrated for, typically five times, so your device being rated for 30Amps should be able to pass 30•5, or 150 Amps.
Do a quick test by simply connecting the device to a power supply of 5 volts, so the Gnd to 0 volts and Vcc to 5 volts and use a multimeter, either analog or digital to measure what is on the output pin.
If you are measuring Vcc, then the device is kaput. If you are measuring Vcc÷2, or say 2.5 volts, then you have a bi-directional device, which would appear to work. If you measure close to zero volts, say a few tens of milli volts, then I would be again hopeful you have a working uni-directional sensor.
Once you have proved that your device either works or doesn't allows you to proceed to testing with real, I mean real current flowing through the main sensing path.
You can use a small 12 volt lamp from a vehicle, say an indicator lamp, something around 5 to 10 Watts. Test it first across the battery to make sure you see light. This proves your battery has charge and that the light works. Next connect the 712 sensor in line in accordance to the correct wiring and again measure the output pit with a multimeter.
Don't use 1/4 watt resistors for this test, full stop.
Once you prove you have a working system for measuring current, then you can bring in the Arduino.
I would suggest you get online and read the data sheets that are available from the Algero website.
Anyhow, if you want, you can see one working from my project, which measures the current from my solar array to my battery system. I have made the Arduino do many things including pushing this data up to my online host, where you can view it in real time. Oppps,I forgot, at present it's raining and near the end of the day, so no solar input until the sun shines again, but you can see it by looking at the trend page and scrolling back in time via some buttons I have on the trend page. http://paulalting.com/hydrosolar/hydrosolar.php
These devices are really quite good as they isolate the sensing side from the measuring side, allowing you to measure current paths not connected to your Arduino supply, which I think is a good thing for many people.
Paul