I would like to build some electronics to automatically and individually control two receptacles on a 20A circuit.
Is the following a good plan?
- Fish 12/4 NM through the wall from the receptacles' box to the below
- Put a box or panel someplace accessible (the rectangle on the left)
- In that box:
- Use UL listed COTS parts for everything
- Follow NEC for wiring methods, spacing, materials, and grounding
- I'll do what I can to make it neat and tidy
- Pass low voltage wires out to a separate box (the rectangle on the right) housing low voltage electronics
The low voltage conductors on the right will be sized according to the (much lower amperage) requirements of the low voltage circuit.
I can do pretty much whatever I want in the low voltage box, right?
I'll ground as needed on the line side of things (the box if it's metallic, the converter and relays if they require it). But am I required (by NEC) to ground anything on the low voltage side? I'm not talking about using DC "ground" in the electronics, or whether V- will be earth potential, but I'm talking about the 12AWG grounding conductor that comes in from the left... does NEC require that for anything on the low voltage side?
I live in Michigan, USA. This is the other half to this question.