Hi there!
I am starting a mini project but I am having some problems figuring out what components to use.
So basically I want to have some kind of component that can read if there is current running through it, and if so, then communicate to the other component wireless that it is on which turns on an LED. I added a poo drawing to help 
( Was thinking of a wireless relay or something)
You need to know what is the nature of the current that is running in that gadget that you want to read?
I mean is it AC/DC?
If its DC its straightforward, thenif its DC is it something in the lines of aduino logic level voltage? that is under 5v?
or the voltage is high?
I am attaching it to a motorbike indicator. I think the bulbs run off 12v. Was looking at RF
Voltage divide the 12v to bring the voltage down to the acceptable voltage that can be read off an arduino thats 5v logical level (if you have a 16mhz 5v arduino) or use a voltage regulator BUT a voltage regulator gets pretty hot and call for a buck module so I think voltage divider way is kind of good, rest you can try using a 7805 with some thermo glue and heat sink attached to it to read the voltage.
