Working with high and low voltages

I want to build a smart outlet using a solid state relay. I also want to keep this project up to electrical code.

So pursuant to NEC 2008 section 800.133

Communications conductors shall not be placed in any raceway, compartment, outlet box, junction box, or similar fitting with conductors of electric light, power, Class 1, non–power-limited fire alarm, or medium-power network-powered broadband communications circuits.

Exception No. 1: Where all of the conductors of electric light, power, Class 1, non–power-limited fire alarm, and medium-power network-powered broadband communications circuits are separated from all of the conductors of communications circuits by a permanent barrier or listed divider.

Exception No. 2: Power conductors in outlet boxes, junction boxes, or similar fittings or compartments where such conductors are introduced solely for power supply to communications equipment. The power circuit conductors shall be routed within the enclosure to maintain a minimum of 6 mm (0.25 in.) separation from the communications circuit conductors.

My plan then was to use a low voltage divider plate in a double gang box, but how do I connect the high voltage components with the divider there? Can I cut the divider and use PVC conduit to protect the high voltage components? Would heat shrink be insulation enough?

I won't attempt to decipher the requirements. At some point there is a relay with half the relay on the high-voltage "side" and half on the low-voltage side...

I want to build a smart outlet using a solid state relay.

The "smart" thing to do is to buy one! :P Commercial home-automation outlets are self-contained with no low-voltage connections coming out of the device. [u]X-10[/u] uses an RF signal over the existing AC wiring. The Z-Wave protocol is wireless RF, and Insteon uses both.

As you know, there are lots of engineering & construction challenges and it's just a lot easier (and probably cheaper) to buy something. I'd recommend buying your controlled outlet, and switches/dimmers (if any), and then if you really want to build something yourself, build the controller(s).

And in any case, I'd recommend sticking with one of the existing home automation protocols. It makes it a lot easier & quicker if you want to upgrade or expand, or if something fails and you need to replace it.


I've had a combination X-10/Insteon system for many years. I've got about 10 controlled lights & outlets and a master timer-controller that's programmed with the computer and then runs stand-alone. Plus, I've got a few wired & wireless "manual" remote controllers around the house. The setup I have can't be controlled over the Internet or with my phone, that could easily be added.

I didn't build any of it myself, except I made a "sunrise dimmer" that plugs into an X-10 controlled outlet. The X-10 master timer/controller turns-on the outlet 10 minutes before my alarm goes off, and the little gizmo I built starts fading-up the light over a 10 minute period. Then after an hour, the X-10 system turns-off the outlet.