DIY Digital Watt Meter

Parts List
20 Amp outlet, Preferably GFCI
Combo toggle / GFCI wall plate eg: Leviton 80421 (toggle holes will be cut out)
100A A/C LCD Digital Panel (P06S-100A or equivalent.
Three gang electrical box
12 gauge stranded hookup

Recommended Tools
Dremmel with plastic cutting blade or Keyhole saw with small teeth.
Crimper tool & crimps or just use twist connectors
File to smooth the cutout on the wall plate

Assembly
Carefully trace base of LCD display on the wall plate. Use Dremmel to cut out and file to shape the hole to fit
Use wiring diagram below as guide. Double click to get a larger image. Reverse the magnetic pickup ring if it does not work (this is shown in find print as I had to do it and did not bother to update the diagram.
I used 15amp and 14 gauge as I did not need 20amp let alone the full 100amp capability

Group box Wiring Diagram

Assembled Unit

Panel Assembly