Mains Filter for Power Line Comunication
The more optimal solution is to make an impedance from a parallel LC circuit so that at the transmission frequency the impedance is high. The parallel LC network would go in series with the line feeding the power supply. Choose the L so that at regular AC frequencies the impedance it presents is just a few ohms then it won't impede AC power voltages reaching the power supply.
You need to have the fuse if you are going to obey regulations for usage of this device - pretty much all SMPS devices have a fuse - it's the last line of defence against your house burning down. Install a fuse.