I have the walls open to studs and before adding drywall I want to run all necessary wires. My house is a flat roof, no attic and the walls have patio doors and lots of large fixed glass so this is the _only way_. (an Eichler for the connoisseurs
The wire ends on the amp side will come out of the wall through recessed cover plates ( amazon.com/dp/B00193U3O0/) that cover those low-voltage orange boxes from HD. On the other end the wires will connect to in-wall speakers.
What are the code requirements for California or other placesfor the conduit ends ? Do I need metallic boxes in the wall on each end? (green boxes in my schematic) What about grounding that conduit in case lightning strikes?
Those metallic boxes are usually used for high voltage and have a green screw where the ground wire goes.
Why not go to your local government and obtain a permit (if necessary)? They will provide all of the details so you can install safely and to code. They will even inspect when you've completed your work.
They make simple sleeves to fit on cut conduit for class 2 wiring. Like inside an IT or phone closet where the wire is allowed to be exposed. Alternately you could also just install a box connector on the conduit end as a bushing. That's overkill and more expensive but you will probably have to buy the simple sleeves in packs of 100 or even 1000 at a commercial supply house so the box connector is probably the best bet for you.
The conduit should be grounded IMO but may not be required by code as this is class 2 wiring. I would use a ground clamp and a bare #8 solid copper wire to the nearest METAL electrical box or cold water pipe. The parts are stocked by HD and Lowes.
thanks for your suggestions. for the box connector does it have to be covered with a plate and accessible or can it be hidden under the drywall? (there are no splices, of course)
i've seen a pack of 10 plastic anti-short bushings specifically for flex conduit but i think they should work for emt as well.
I think what you saw were MC or BX bushings which are not for EMT or even hollow FLEX.
You should be able to just have the wire exit the conduit and come out through a LV ring - same as using the plastic ENT or "smurf". It doesn't need a box in most residential codes for class 2 low voltage stuff. You just don't want the wire or cable to get damaged on the sharp cut end of the EMT. The box connector is just used as a bushing.
Now I will say that if you go to all this trouble with EMT, why not just use a metal box and drywall reducer ring. It's less than a dollar for both even at home center prices. This would be the most professional way to do the job if using EMT and will then meet even the most strict commercial code requirements.