Step 3: Enough talking time to build.
The cord for the Plugstrip is cut in half and run through the electrical box. The neutral (white wire) is spliced with a crimp terminal. The grounds (green wire) are spliced and connected to the metal chassis for safety. The hot wire (black) is connected through the SSR with crimp terminals. This concludes the line voltage wiring.
The +5V and Ground from the USB cable (pins1 and 4) are are connected to one end of the fuse block, and one TVSS The TVSS diodes are simply crimped into the connectors for the fuse blocks. Simple, fast, easy. Then two wires are run from the other end of the fuses (with another TVSS) to the control terminals of the SSR. Most SSR's will have one of the control terminals marked for the positive (+) lead. Make sure to get the polarity right.
Make sure to insulate the other two wires in the USB cable from each other and the metal case. If you do not you can short out the USB buss and cause all kinds of other problems.
This concludes the wiring.
I added a small piece of plastic (recycled blister packaging) to form a voltage barrier between the high and low voltage sides of the case, as extra insurance.