This might be a stupid question that everybody knows!  I am using DCC, and using mainly PECO electrofrog turnouts, just a few insulfrog. All are adapted for DCC.

Are two insul rail joiners, one on either side of the V at the frog end sufficient? Or do all four rails need them?

   

Hi Allan,
Just the two will do 
Gerard 

Thanks Gerard, I've been over doing it!!