I am wondering if those wiring would be useful in a home environment:

  • Low-voltage DC wiring (isolated from mains,) for example a DC 12V system, in addition to the mains power.
  • Optical fiber instead of Ethernet cables for networking.

Lots of modern electronics run on low-voltage DC power (so. Many. Wall. Warts) so why not set a LVDC power distribution system up common for the entire home? Mains to 12V DC isolated power supplies are fairly common now with higher than 95% efficiency, and switch-mode DC-DC converters stepping the voltage down to 5V (USB powered gear) are highly efficient too, reaching 98% in cases. Home area are small enough for the I2R loss to be negligible.

Fiber optics networking is interference-proof (not susceptible to any EMI) and future-proof (capable of up to 100Gbps Ethernet using the same fiber as used in older standards) while used server-grade optical fiber gear are fairly cheap. Optical fiber can run along mains in the same piping as there is no conductor in optical fibers. There are also wall panel style optical fiber to Ethernet cable bridges (most of which requires the aforementioned LVDC system or fiber-mains colocation to work)

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    It isn't exactly clear what you're asking: "do they sell such systems?", "would this be useful?", or "anybody want one?"? We're really structured for clear questions which have single clear answers; you might consider rewriting your question so it fits better. – Daniel Griscom Mar 11 '16 at 12:18
  • @DanielGriscom Read again and you will see the word useful. – Maxthon Chan Mar 11 '16 at 13:25

Sure. Low voltage systems have a lot of versatility. You can put a battery on them, so they stay up when the power fails. You can add solar panels, so they stay up in long outages. Many routers and DSL/cable modems actually want 12VDC (the network stays up because the central office has batteries/generators). It's easy to charge phones and tablets from 12VDC. LED lighting is not a problem at either 12VDC or 24VDC (light strips and "bulbs" intended for RVs.)

For heat, furnace controls can be managed either by switch-mode synthesizing 24VAC or finding components happy to run on 24VDC, including smart thermostats. Or Empire-style furnaces don't need any electricity at all, and this can be a backup furnace, with a plan to close off parts of the house it can't heat. A refrigerator could be modified so its 120VAC inverter only runs when there's a cooling call. A simple gas stove/oven doesn't need electricity either. You could make a home fully functional in power outages, complete with internet and media streaming.

That pretty much describes my next house.

However, as you may know, NEC prohibits low voltage wiring in the same conduits and boxes as 120/240V unless the boxes are subdivided with approved dividers. Non-conductive fiber-optic is OK. Also you are not allowed to hang "other stuff" on the outside of 120/240V power conduit, raceways, busways etc.

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  • I believe 12V can run along Ethernet (if twisted pairs are still used,) phone lines or cable TV lines. Fiber optics just can go absolutely anywhere everywhere as those are nonconductive. About furnace, refrigerators and AC I think the circuitry can be modified to separate the power section and control section, with the power section still connected to mains and control section (mostly low-voltage microcontrollers already) running off the LVDC system. – Maxthon Chan Mar 11 '16 at 8:16
  • Since you mentioned solar panels and batteries, a solar-powered battery-backed LVDC network can stay off grid (at least most of the time) if the solar panels and the batteries have enough capacity. Moving as many appliances as possible to this off-grid LVDC network means you don't usually need to pay for the electricity used by appliances attached to it. – Maxthon Chan Mar 11 '16 at 8:36
  • Not to mention saving the conversion losses of a dozen little power supplies that convert 120V to 12V. They even make 120/12V TVs now. Time was, off-grid people bought these $2000 refrigerators with 6" sidewalls, but now solar is cheaper, inverters and fridges more efficient, and now they just say but a good energy-star unit. Batteries, however, are not cheaper. – Harper - Reinstate Monica Mar 11 '16 at 21:46

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