I've the following circuit , that used to measure the current through shunt resistance , 

The circuit have analog & digital ground , 
the terminals 1 ,2 ,3 are for AC source . 

I need to protect this circuit from shorts .

So where's the right place to put the fuse ? & how to know that this is the right place ? 

Will be a fuse on the digital side and the analog side ? 


any other recommendation for this circuit ? I found out that 7805 voltage regulator is getting hot fast . 


![enter image description here][1]


  [1]: https://i.sstatic.net/AoKqu.png