TED2009: Electric Fault Circuit Interrupter

200902051456 A description of Electric Fault Circuit Interrupter (EFCI) on stage at TED2009.

Smoke alarms are great -- they detect fires but don't prevent them. One of main causes of fires is electricity.

How does electricity ignite fires? Faulty, overloaded or misused outlets. 83% of all fires start at loads below circuit breakers (invented by Edison) trip.

By putting a 10-cent data tag (like RFID) in an appliance plug and a reader in the electrical outlet, you can prevent fires. The appliance's safe operating parameters are embedded in the plug. If there's an overload, the power shuts off. Also, outlets are off unless the appliance with the chip is plugged in. That means a kid can stick a fork in the outlet and not get shocked.

Can save thousands of lives and conserve energy.


  1. Not being backwards compatible also causes issues for people who replace cords or make their own electronics. Also, you mention the 10 cent chip, but how much would the outlet cost? I also don’t see how this saves energy.

  2. Sort of like an authentication system for your electrical wiring. The problem is the same one any new authentication method encounters. Only components which are compatible with the new method can access the resource. Some authentication systems voluntarily “downgrade”, should the component they’re interfacing with not support modern authentication. But that kind of eliminates the point of having the newer method at all…


  3. Isn’t that what Underwriter’s Laboratory is for? Making sure devices don’t burst into flames when you plug them in?

  4. So if you plug in an appliance without an RFID tag what happens.

    Most overheated circuits are from poor contacts under otherwise legitimate loads. Spend the ten cents on contact cleaner and the rest of the money on GFI outlets.

  5. Osprey, I believe the idea is that each outlet is passive/off until activated by a RFID-bearing plug. The plugs are specific to the appliance to which they are attached (another thought: how easy would it be to replace damaged plugs?)

  6. since it’s just an RFID tag backwards compatibility is a snap, just stuck a little adhesive tag onto your old non compliant plugs. This would be great, i would totally retrofit my house with these. Of course that would mean I would never get the entertainment my dad got when I figured out the plug blocks and got a piece of metal in there.

  7. until, of course, your appliance rental subscription expires, or your appliance vendor ceases upgrading codes to be compatible with new outlets and your toaster is no longer compatible with the operating system of your house, and your zombied refrigerator starts sending denial of service attacks to the blender, and you find you must hack the rfid plugs off of everything if you want to use it with any kind of peace of mind, and consistency, so you use a little electrical tape and fan cords, to convince your house that your television is not going to burn it down,and maybe you find that your taping is a little subpar and burns down your house anyway, only now your insurance company won’t cover it because they have been sniffing your tags and show you to be a high risk heavy electrical current user and monster starts selling gold plated extension cords that promise to allow massive thruput of electricity and you hang yourself with one, in the dark.

  8. actually, a smart domestic power system is a good idea and inevitable. Progress. Knob and tube still works, but we can do better.

  9. This all sounds really cool. I would love to have a house with an easy green switch that allowed me to turn off the outlets supplying my TV and computer etc.

    But if I have learned anything from the Jurassic Park movies, its that if anything that can go wrong, will go wrong.

    So I picture myself with a Refrigerator (blender, stove, or other expensive device) where these things go bad (can that happen?) and it keeps shutting itself down, and then back on. So I end up replacing everything in my refrigerator 3 times, or learning to hate crunchy daiquiris before I finally figure out that I need to go get raked over the coals by a cord replacer.

    How would you turn a tripped item back on, BTW?

  10. Or you could put a fuse directly in the plug that corresponds to the maximum safe operating current of the device.

    You know….like the UK have been doing for 50+ years.

    This also would require each receptacle to contain a set of relays, which would get bulky…

  11. Smart domestic systems are fine, as are 10 cent RFID tags. But when you tell the someone his next power strip will be over 30$ rather than the ones he got at the dollar store, that’s when the issue comes. The already available half-decent power strips that have “electronic fuses” will already detect overcharges and changes in temperature (and if you’re European they come with children-safe plastic caps)… the electronics for those come at a fraction of a price (not to mention power consumption!) of a RFID scanner and the associated circuit measurements.

    Yes, the way we distribute power around the house should be reviewed. It’s not efficient and it’s obviously not geared for modern usages. Count how many power bricks/chargers you have laying around the house, for starters. Maybe it’s time for a low-voltage rail norm to emerge?

  12. The guy down the street from my folks invented the ground fault interrupter. He is not poor.

  13. What happens when suddenly you have to buy all your appliances from electricity company “approved” suppliers (at 3x normal prices), because suddenly every outlet is DRMed?

  14. Ah yes, the infallible 10 cent data tag. Uh, huh. Sounds like more crap we don’t need, like RFIDs themselves.

  15. I came to comment derisively about the excessive complexity of this system, but you all beat me to it.

    UK fuse-in-plug sounds brilliant tho.

  16. Sure, the TAGS are cheap, but that’s the only cheap part of an RFID system. I remember a year or so ago there was a breakthrough announced in RFID reader prices — they were able to make short range readers for less than $100. That’s still a bit more than I want to pay for an electrical outlet, though.

  17. And you can’t operate the appliance without an RFID chip embedded in your hand.

    /sees where this is going
    //Illuminati have infiltrated TED

  18. But wouldn’t it be pretty trivial to make some kind of cheap plug adaptor or something to provide backwards compatibility? This way, with the help of government and industry leaders (heh), you could do a phased deployment over several years. Users with RFID enabled devices get the safety benefits, users with the adaptor are no worse off then they would be normally.

  19. Why does everything have to be freakin’ RFID? For a single point of data like this, a resistor in the plug and a physical contact (probably in the middle of the three prongs) is more than high tech enough.

    But if you’re going to go to all that complexity, let’s ditch AC on the last few yards. Or at least offer DC as an option on one of the two plugs. It’s insane that every device has its own little inefficient made-in-China transformer. Get rid of all your wall warts and power supplies. Put a nice big regulated power supply in the garage.

  20. Or at least offer DC as an option on one of the two plugs. It’s insane that every device has its own little inefficient made-in-China transformer.

    I’d love to do that, but all wall warts are not equal. Some give 12V, 100mA, others give 3.5V, 2A etc, etc.
    If everyone could standardise on one voltage for their devices (it’d have to be pretty high to given enough juice to run the heftier ones) that would be swell. Oh,wait – they already have!

  21. This seems at least a little anti-maker. If you’ve got a frayed cord, and you replace it yourself, you’d have to get yet another specialized “part.” And if you wanted to make something entirely new…

  22. Can I still use my 1950’s era electric waffle iron? That thing sucks up the juice and puts out heat like nobody’s business, but I do love them waffles.

  23. Like KWillets said, it’s usually dirty contacts that overheat. If you want to build something into the sockets,a simple temperature sensor to shut off the power would probably be more useful, and have no backwards compatibility issue.

  24. I agree with Jimkirk – this could be done easier & made to handle the more common faults. I like the fuse-in-the-cord idea (like christmas tree lights have).

    Also, I’d like to see a low-voltage-cutout for cases where an extension cord is overloaded (for the cord’s rating, but not for the circuit breaker’s rating). That doesn’t solve all the extension cord problems — for example, a cord stretched out will remain cool, but one with all of its length stuffed in to an insulated box will get really hot.

    Also, like Takashi said, power strips will be very expensive.. and extension cords will be, too. At least if you ditched the RFID (for either power-line communication, or a simple resistor), then the extension cord would be cheaper to make.

  25. How absurd.

    Saftey systems should be as simple as possible. Adding this amount of complexity for no good reason will only increase the potential risks.

    Good plug top fusing is a pretty old concept in the UK, and as long as the correct fuses are installed it will work very well. Most appliances need no more than a 2 or 3 amp fuse (which will of course allow through up to 4 or 6amps momentarily before blowing).

    Its unfortunate that most well known manufacturers ship kit with 13amp fuses on IEC leads which are only designed to take up to 10A. They kit they plug into probably only needs 5 or less.

  26. The issues with shared extra low voltage supplies is that you create high current ground loops between the devices on signal cables that interconnect them.

    With most low voltage devices again stepping the 12/9/whatever down to 3.3 internally there is a switching regulator in the device to do that, which basically puts a lot of crap on the DC input – if thats shared between say for example your PMP charger stand and your small speakers – you will have lots of noise unless they spend a lot more on the device.

    There is also an issue with internationalization – a separate wall wart for each regulatory domain is an easy way to maintain compliance without spending a lot. With a potentially high current DC supply there will be even more challenges to overcome. Look how abused USB gets as a power source because they didn’t mandate over current detection on it, don’t want that happening to a DC rail used for some appliances that may be quite critical to your house.

  27. And lets not forget P=I*V..

    So on that low voltage rail around your house, probably 500 ft or so of wire, you’ll need what, probably a 6 to 4 gauge cable to get acceptable voltage loss?

    Sure a low voltage idea sounds good in theory. But until we have room temp super conductors it isn’t going to fly.

    Now I do like the idea of a standardized DC input voltage. That would make life much much easier.

  28. A simpler solution is to use low power AC, and maybe a higher frequency. Then power conversion could be done with much smaller electronics. It would also make inductive charging common.

  29. WOW. There is so much negativity being shown in these comments. Just a few with positive suggestions. The UK system with a fuse in the plug is actually quite good and even better when coupled with a combination of an ELCB (Earth Leakage Circuit Breaker) and an overload breaker on the extension cord.

    My negativity? The joy of so many ‘standards’.

  30. Why bother with RFID?

    You’ve got a copper connection between the the appliance and the power outlet that is perfectly capable of transmitting data. (Think Ethernet over House Wiring)

    This also solves the issue of having two different devices with different current ‘allowances’ plugged into an outlet.

  31. The “core idea” is not only sound but if Moore’s Law still holds as true? There’s a Rule I keep hammering into people that silences a lot of the
    “Yahbuts” with logic. Serial #001 may indeed cost a megabuck. S/n 1,000,000 is down to the intrinsic parts cost. S/n 10 million and up might have a negative cost due to selling the TECH embedded know-how to other players in the field. With a wry grin at this potentially being funding worthy as economic stimulus. “The future of safety is made in AMERICA!”

    And the quite true comments about loose/dirty contacts being another economic stimulus possibility. “an army of civilian “safety wardens”
    Inspecting and tagging for refit externally if safe-or replacement if not, ALL the power connections in America that anyone wanted checked. Would it be “make work” or a valid safety initiative if tied into deployment of these intelligent power systems? Hell- tie it into both the Census and a nationwide energy audit offer!

    DO think carefully about the potential rewards involved in this. The worker going over appliances to read nameplate data for selection of the proper RFID stick/glue on bug could easily do so as part of an energy audit. And fixing the interlock plug “sandwich style” to the outlet with a long thru screw as we do with the very same “2 to 4 or 6” socket devices that are part of the originating issue!

    Failing all else? we’d simply deploy these smart systems by the existing methods of code revision and market forces. With steep insurance discounts for compliance?

    Oh- the closing rebuttal to what is essentially saying “what about the legacy stuff?” Well- one comment about stick-ons is quite viable as a “Last Resort first” fix. The other aspect being past precedent- We’ve had this constant upgrade since we went from screw based iron cords thru the fused Europlugs and American 2 wire polarized plugs- to proposals like this. Each one made our world a bit safer and more “graceful failure mode” after all. As opposed to deadly failure modes of ignoring new tech advances. Though there IS one “social darwinist” stridency clamoring against all safety measures. It was stated a few decades ago in muttered rants that “the empire will fall from appliances coming with a mains plug attached as the stupid won’t kill themselves misfitting one” So? which world do you wish to have? one where the plug&socket save or kill..

  32. i think a power specific extension for to the usb protocol would be the ideal replacement for wall warts

    legacy devices would default to 5v 150ma, while compatible devices could negotiate for more power.

    This would make it economical for people to have a lower number of higher quality power supplies, extensible even to laptops.
    keyed connectors may be necessary higher draw devices.

    If implemented this could be a good platform for energy saving features like managing devices on standby better & offloading less important devices to off peak power.

    ideally this would be an open free to license connector & protocol.

    tax incentives for manufacturing high efficiency chargers & a law stating manufactures must accept return of unwanted chargers would do a lot to ensure quick uptake of this standard.

  33. If you’ve got a house with 500′ power runs, you can afford more than one DC head point. And there’s nothing that says it has to be super-low voltage. 12V is fine for RVs and boats, but there are proposals to switch the standard for cars to a higher voltage due to the amount of power being used in vehicles these days. No reason you couldn’t run 36 or 48V for home use. Put a buck-boost converter on a chip at the plug, with resistor-selected step-down to whatever the individual appliance needs.

  34. Takuan,

    Knob and tube is superior in some ways. The advantage of the single cord/multiple conducter lines is that they are fast and easy to run. The K&T is still acceptable to code, they tolerate overloads because they are out in the open where they can shed heat, and they age very well so long as you don’t mess with them.

  35. As obviously wonderful as this is, it fails to address all of the appliances that are already “out there”. My colleague and I have developed a new method of load control where the power point (wall socket to some of you) can be retrofitted to regulate the amount of actual power needed to operate the appliance. As an example, an incandescent lamp uses 5% of the power that runs through the filament to create light – 95% is wasted as heat. Our system tells the light (well kind of) that it is only going to get the 5% and the rest is kept in the loop circuit. We have done this with microwaves, refrigerators, televisions, computer, electric drills, lights (of course). The regulation process is appliance specific, so the best thing to do is retrofit into your outlets (power points) but we have also designed a “plug and play” system that can be plugged into your regular power point. The result is a considerable reduction in power usage and yet getting the same benefits. Cheers. TED isn’t the only place that innovation is taking place. ;)

  36. smart appliances that learn your house code from a plug in security brain and then, once set, will refuse to work on other power systems unless re-set/cleared for re-imprinting?

  37. Sounds like they are inventing lies about fire statistics in order to sell this:


    Cooking is the primary cause of residential fires (Ahrens 2003).

    compared to what this post says:
    How does electricity ignite fires? Faulty, overloaded or misused outlets. 83% of all fires start at loads below circuit breakers (invented by Edison) trip.

  38. Solving the socket imcompatibility is easy. Plus imagine the money Electrician’s would make in retrofitting ALL 120vac outlets in America so the new appliances would work in existing power sockets.

    We just need OSHA to pass one regulation…and BAM…electricians are all back to work.

    See how easy it is … Central Planning is going to save America … (or at least until “Other People’s Money” runs out.



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