relay that triggers when ground is broken

Hi. New guy here. Sorry if this has been asked already. I am trying to make an alarm of sorts and need a relay that will trigger when a ground is broken. Will not be a lot of load on it. just some lights and a horn flashing. thanks

Thank you I will try that. I am not an electrician by any means and I hope I explained it right.

Ok, so what I am trying is working so far..... now, as I understand, In order to get multiple triggers can I splice in multiple wires into the ground using diodes? Or would I have to use more relays?

The relay is going to be energized until the ground is broken.  If you use a standard Bosch/Now Tyco relay, it will draw 160 Miilliamps constantly.  If you drive the car every day you may be OK.  If you leave the car parked for 2 or more days, it will drain the battery.  Radio Shack sells a 12 volt relay that draws around 40 Milliamps.  I would look into that if you are still wanting to try this.Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

Ok I understand... this is mainly for my boat when I am on the road in a strange town overnight with it.

Do you have a part number or a link to the radio shack relay?

http://www.radioshack.com/product/index.jsp?productid=2062482   This relay is not numbered or layed out as described earlier. You need to use the 2 coil connections to trigger the relay.  And for your lights and sirens, apply power to the Common connection.  Connect the lights and siren to the Normally Closed connection.Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

Use a transistor such as a MOSFET instead of a relay to do the signal inverting and you can essentially eliminate standby battery drain.