Reverse ammeter readings

[Mad Mac]

I am useless with electrical issues, so I hope someone can diagnose this problem for me: When I turn the kill-switch on (with key out), the ammeter moves left (ie reads negative amps) but nothing on the car is turned on. Then when I insert the key and turn it on, the needle moves right (positive amps) still with nothing turned on except the key. I am sure this is not what is meant to happen - can anyone tell me whats going on?