This is a philosophical question. Over the last few years, many of the household devices, particularly those that are more mobile and etc are DC devices. Are we at some point where a DC household may become a possibility and Edisons dream might come true??

The array of DC devices

  1. Internet stuff - routers, modems
  2. Most complex computer electronics - Desktops, laptops, NAS, phones, tablets, gaming consoles, etc
  3. Lighting - LED
  4. More that I cant think of or perhaps know which also convert AC -> DC

Problems with AC

  1. Each device needs its own power supply ( AC-> DC power brick). This is
    a) Unpleasant to look at and deal with, and
    b) a costly point of failure.

  2. Each power brick may or may not be optimized, as far as power conversion goes.

Alternative - A central (or a few ) high capacity power adapter which converts the AC into a DC power grid for the house which can then be tapped directly by the various devices. This eliminates the need for the power brick, and hopefully the central power adapter is of state of the art, and can be upgraded seperately from the devices, as needed.

Need standardization of:

  1. Device voltage. Currently devices use 5/ 9 / 12 or others I may not be aware of, for this idea to work they need to work with one particular one, unless switching between voltages is cheap enough, or multiple DC lines are provided.
  2. Power socket input. Each device appears to have its own input socket type, this should standardize if the power supply cable should be comoditized, perhaps USB - C will play a part here.
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    \$\begingroup\$ We are not a discussion site. This is a question for philosophers. :) \$\endgroup\$ – Passerby Apr 4 '16 at 7:25
  • \$\begingroup\$ @Passerby what might be a good place for such a question? This question can be made a bit more concrete by just answering what stands in the way of this idea? \$\endgroup\$ – Karthik T Apr 4 '16 at 7:30
  • \$\begingroup\$ I'm no philosopher but I can sill refute the idea easily with some hard-core engineering facts, see my answer. \$\endgroup\$ – Bimpelrekkie Apr 4 '16 at 7:34
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    \$\begingroup\$ Generally DC is only good for distances of less than 5m (16ft) and generally start losing efficiency for distances of around 2m (6ft) so an all-DC house starts to make sense if people start living in doll houses. \$\endgroup\$ – slebetman Apr 4 '16 at 9:02
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    \$\begingroup\$ What seems to be becoming more common is AC outlets with built-in USB power supplies for convenience - effectively hiding the power brick in the wall. \$\endgroup\$ – pjc50 Apr 4 '16 at 9:02

Edisons dream might come true

No because Edison wanted to distribute power (over long distance) using DC which is cumbersome and lossy. That's why we use AC. The appliances you talk about take only limited amounts of power. Using a DC distribution system for that is also lossy even over the short distances inside your house. To limit the power loss thick (copper) cables would be needed making it an expensive solution.

Your "problems with AC" are not really problems if you see how cheaply we can now make power adapters. And although maybe not optimized I bet it is still more efficient that having a "low voltage DC distribution bus" running around your house. This is due to the cost of copper as I mentioned above. And you need thick copper to limit voltage drop = power loss.

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  • \$\begingroup\$ yeah I am ignoring the "distribute" part of the dream, Although that seems to be coming true in bits as well - nytimes.com/cwire/2009/06/15/… \$\endgroup\$ – Karthik T Apr 4 '16 at 7:33
  • \$\begingroup\$ It is for the power loss that I thought perhaps one per room might be more effective? \$\endgroup\$ – Karthik T Apr 4 '16 at 7:36
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    \$\begingroup\$ Why is DC transmission more lossy than AC? \$\endgroup\$ – Chu Apr 4 '16 at 8:16
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    \$\begingroup\$ @Chu Basically electric current is the problem, current gives power loss so to distribute power over a distance you want low current. With AC you can use a transformer to increase the voltage and this decreases the current. That is why power is distributed (over land) using high voltage AC. Under water capacitance to water is an issue so there High voltage DC is used. However, it is more complex/expensive to make / use high voltage DC compared to AC. So that is why High voltage DC is only used under water. \$\endgroup\$ – Bimpelrekkie Apr 4 '16 at 9:46
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    \$\begingroup\$ @yo' It's quite easy to get AC from DC and then convert to whatever you need in the domestic environment. More importantly, transmission by DC means you don't have the losses associated with the reactive component of current in the transmission lines. \$\endgroup\$ – Chu Apr 4 '16 at 10:15


While low power devices (like smart phones or routers) are common, there are many high power devices in an average home: hoover, hair dryer, lawn mower, etc. In fact, compared to a smart phone, even just a laptop needs a lot of power.

Power = Current * Voltage. You don't want high current as you then need thick wires. So high voltage makes sense for high power devices - which is exactly what current AC sockets give you. It is easier to change AV voltage than DC, because transformers work with AC. With modern electronics, transforming DC voltage is practical, so in theory you could have a high-voltage DC system. But there's just no point - it works better with AC.

Anyway, there is already a solution to get rid of the annoying power bricks:

enter image description here

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    \$\begingroup\$ I'd never buy something like this because if the build-in 5V supply breaks and starts smoking, I cannot quickly disconnect it from the mains. I simply do not want any mains-connected electronics to be connected to the mains permanently. \$\endgroup\$ – Bimpelrekkie Apr 4 '16 at 11:21
  • \$\begingroup\$ @FakeMoustache - did you just downvote me because you don't like these USB sockets? \$\endgroup\$ – paj28 Apr 4 '16 at 11:29
  • \$\begingroup\$ Nope that was someone else \$\endgroup\$ – Bimpelrekkie Apr 4 '16 at 12:00
  • \$\begingroup\$ Are you surprised of an opinion-based downvote when answering an opinion-based question? \$\endgroup\$ – Dmitry Grigoryev Apr 4 '16 at 12:03
  • \$\begingroup\$ @DmitryGrigoryev - no opinions here, just solid facts :) \$\endgroup\$ – paj28 Apr 4 '16 at 12:14

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