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Power Hardware Hacking Toys Technology

Home Power Monitoring Hack 220

Posted by Zonk from the feel-the-force-flow-around-you dept.
dvogt writes "You think your power bill is bad? I built a power monitoring system to monitor every circuit in my house with three second resolution for over a year. And while I had to rewire all my electrical to do it, I can now reconcile my electricity bill down to the penny... Of course when my wife figured out most of the bill was because of my computer gear I had to build her a dome, so reader beware!" From the article: "About a year ago I developed a web based power monitoring application for data centers. The application was designed to monitor thousands of individual branch circuits using current transducers at the breaker panels. Among other things, the data logging requirements were to provide one year of min/max/mean measurement data with one minute resolution per circuit. Since I had all the hardware for testing, I figured what better way to test things than to install it in my own home."
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Home Power Monitoring Hack More

Home Power Monitoring Hack

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  • Another way to do it: read the meter (Score:5, Interesting)

    by seanadams.com ( 463190 ) * on Saturday July 16, 2005 @07:47PM (#13084029) Homepage
    If you want to monitor the whole house (as opposed to individual circuits) you can do it for less than $20 in parts plus a Linux machine. I made a system to do this [seanadams.com] a couple years ago - unfortunately I never hooked it up again after I moved, but it worked just fine.

    If you're lucky enough to have the kind of electric meter with a blinking LED on it, you could do this much more simply. Also if I had to do this again I would ditch the op-amp circuit and feed the signal from the photo-resistor straight into the sound card and then do the filtering in software (if the photo-resistor is exposed to sunlight it can be a little tricky to tune using this circuit - software could be smarter).

    • Re:Another way to do it: read the meter (Score:4, Insightful)

      by d2_m_viant ( 811261 ) on Saturday July 16, 2005 @07:57PM (#13084074)
      Yes, but that won't do much if the power company is cheating you. The article's way, you'd be more able to catch the power company charging you for something you didn't use.

      On a side note: Imagine trying to convince the customer service rep on the phone that you rewired your house with a homemade power monitoring system and your monthly audits of your electrical usage uncovered the error...me thinks you'd have better luck convincing a Slashdot reader to install the WeatherBug...

      • Re:Another way to do it: read the meter (Score:4, Informative)

        by seanadams.com ( 463190 ) * on Saturday July 16, 2005 @08:01PM (#13084095) Homepage

        If you can read the wheel then you can test its accuracy. Just turn a known load on and off and measure the change.

        You can do that with just a stop watch and some math.
        • Possible. I tried this method, but was coming up with irratic results. I found out that my fridge uses electricity almost continuously, but uses a variable amont of electricity. I was very surprised by this. I think you will find the same thing with your PC as well.

          So, for many applications, your method works. But if you want to measure your average PC's power usage over a period for days.... ain't gonna happen.

          Plus this IS slashdot. If it ain't a geek implementation, it ain't worth doing ;)
      • Speaking as a customer service rep at a electrical utility, I think it would be one of my more NORMAL calls.
        Typically speaking though, meters do not 'speed up.' With age, they slow down which does not work in the utility's favor, which is why they usually have a periodic meter replacement program, ie every 5 years.
        I haven't ever sent out a service order on a meter that's ever tested too fast.
        Many utility companies (like the one I work for) have automated metering, with meters transmitting at 917mhz ba

    • Good hack. You can also get readings of the mains post-power-meter with nothing more than a couple of ferrite toriod cores and some resistor divider bridges, feeding voltage and induced voltage (which is proportional to current) into a sound card's mic and line in inputs. I have that working downstairs, though I haven't bothered to calibrate it.

      The toriods can be split carefully with a chisel, and need 70 to 200 turns on them, evenly spaced. They might saturate, but that can be fixed either through usin
    • Also if I had to do this again I would ditch the op-amp circuit and feed the signal from the photo-resistor straight into the sound card and then do the filtering in software (if the photo-resistor is exposed to sunlight it can be a little tricky to tune using this circuit - software could be smarter).
      I tried to read this sentence to my mother. She combusted halfways through.

    • 1 minute resolution is not enough (Score:5, Interesting)

      by zippthorne ( 748122 ) on Saturday July 16, 2005 @08:56PM (#13084321) Journal
      In fact he must sample at greater than 120hz* to get meaningful results. He has neglected the possibility that voltage and current can and will be out of phase for each of the loads in his house. Without determining the phase difference, there is no way to accurately deterimne the average power over any interval.

      There are quite a few meters that measure RMS voltage and RMS current, (though most of the cheap ones actually measure peak values and multiply by .707), there are fewer still that accurately resolve power factor [wikipedia.org]

      This is a common mistake to make for first year EE students and "over-unity" power converter proponants.

      As I understand it, the Kill-A-Watt, http://www.professionalequipment.com/xq/ASP/Produc tID.3375/id.5/subID.57/qx/default.htm [profession...ipment.com] makes a pretty good approximation. In fact, it even does the integration for you. You could pepper every outlet with these things or just move them around as needed.

      *I know you need 2f according to nyquist to resolve the frequency, but I'm not sure what you need to gather the phase information**

      ** There are other ways to obtain the phase information involving bridge circuits and such, It does not appear that the boards in question provide that information.
      • [disclaimer: the original site is down, so I haven't read the article ]

        In fact he must sample at greater than 120hz* to get meaningful results.

        Well, he could sample 120 times a second, but then only keep one data point for each three seconds, with that one data point being calculated from the 360 readings taken before it. It could save a lot of disk space ...

        He has neglected the possibility that voltage and current can and will be out of phase for each of the loads in his house.

        And you've

      • I did my undergrad thesis in home power metering, and used 2 different models of Brand power meters [brandelectronics.com]. They sample current and voltage at 4kHz to accurately measure true power factor (see their description [brandelectronics.com]). Single circuit "plug-through" meters are $150-350; the higher-end ones have computer connectivity and datalogging.

        Another option for those interested in exploring home power use--and not ignoring power factor--is the Watt's Up? [promolife.com] meter (also plug-through, $100-150, with computer connectivity at the high-

        • Re:1 minute resolution is not enough (Score:5, Informative)

          by Technician ( 215283 ) on Sunday July 17, 2005 @02:07AM (#13085331)
          Power factor is more of issue for commercial electricity customers, who are billed for non-unity power factor and often install huge banks of capacitors to correct it

          Here is a brief rundown and how it helps.
          In DC Volts times Amps = Watts.
          In AC Volta times Amps times Power factor = Watts.
          Volts times Amps minus Watts = VAR's (Volt Amps Reactive) Power Factor is always between 0 and 1.0 and is either inductive or capacitive. 1.0 = no reactive current.

          How does reactive power affect the power company?
          Take for example an air conditioner. It's electric motor has windings that are inductive. The current is not directly in phase with the applied voltage. The current lags. The AC may draw 15 Amps, but on a 120 Volt circuit only consume 1200 Watts. 15 * 120 = 1800 Volt-Amps. 1200 Watts is the power used. 120 Volts * 15 Amps * 0.66667 PF = 1200 Watts. This leaves a component of 600 VAR's or 5 Amps of reactive current and a Power Factor of 0.66667 inductive. Drawing 5 Amps seems like no big deal to an end consumer. However for the power company, it means the transformer has an extra 5 amps as well as it's circuit breaker and wires. All wire has resiance. A current flowing in a wire will turn some of that voltage caused by the current to produce real Watts (heat) in the wire, transformer and circuit breakers. Your 5 Amps of 0 Watts costs the power company money to heat their lines and reduce their capicity.

          Now the neat way to fix it. Capacitors don't heat (except for some small losses) Add some capacitors so the capacitive reactance = the inductive reactance on the line. In the above example 5 Amps is needed.

          When done, the 5 Amps of capacitive reactance is out of phase with the inductive reactance by 180 degrees (90 degrees to the resitive load) and thus the 600 VAR's (5 Amps Inductive) from the AC is balanced with 600 VAR's (5 Amps Capacitive) from the capacitors. The nice thing is now the AC gets the current for the VAR's from the capacitors, not the power company. Now the AC uses only 10 Amps from the power company, not the 15 it used to. (The AC still draws 15 Amps, but the combined load of the AC and Capacitors is now 10 Amps and still 1200 Watts.) This is why the power company would like you to adjust your VAR's. If the power company tried to adjust it, (sometimes they do) by adding capacitors, then they may be unbalanced the other way (capacitive) when your AC shuts down but the capacitors don't.)

      • Re:1 minute resolution is not enough (Score:5, Interesting)

        by dan42 ( 740934 ) on Sunday July 17, 2005 @12:18AM (#13084995)

        I believe the 1 minute resolution was for the reported data and not the actual analog sampling rate. The 1 minute data may (should) be the RMS of the all the samples collected during that minute.
        His device seems to be a prototype version of the Veris H663 [veris.com]. The released version of the device apparently samples at 1280Hz and reports data every second.
        The "phase information" you mention is good to have, but only if the power is at just one frequency. The fact is that computers (as with most devices running of a switching power supply) draw current as a short pulse during the peaks of the input voltage waveform (with no phase angle between voltage and current at the fundamental frequency). Often the 60Hz component (or whatever the fundamental frequency) makes up only half the RMS current. And since these harmonics are only dominant in the current and not the voltage waveform, the real power consumed by a computer will typically be ~50% x RMScurrent x RMSvoltage (even though the phase angle is zero).
        • Yes, I failed to mention the effects of DC converters and such.

          The board may sample at a million hz and report data every second, but if he just takes average |V| and average |I|, the million hz is useless. If the board is calculating the power at every sample and reporting it to his machine, that's a different story altogether.

          From my reading of TFA, it appeared he was only sampling and and multiplying them in his computer to determine the

          over the interval. No mention is made of whether the board i

      • You are wrong about the resolution. He's sampling every 3 seconds and making a min/max/mean database entry out of 20 samples, every minute.

        You are wrong about the importance of the power factor. It is not even measured by the power companiesl; they ignore it in their billing. He cares about the bill, not some unmeasurable factor.

        This is a common mistake to make for young scientists who fancy themselves engineers, electrical or otherwise.

        Once upon a time, a young scientist learned of an home power monitor
      • *I know you need 2f according to nyquist to resolve the frequency, but I'm not sure what you need to gather the phase information**


        The same of course. Nyquist sampling allows for perfect reconstruction of ALL info, hence also phase info.

      • As I understand it, the Kill-A-Watt, http://www.professionalequipment.com/xq/ASP/Produc tID.3375/id.5/subID.57/qx/default.htm [profession...ipment.com] makes a pretty good approximation. In fact, it even does the integration for you. You could pepper every outlet with these things or just move them around as needed.

        Very nice... I was going to mention the Kill-A-Watt here if nobody else did.

        I only have one ($30) and it's all I've ever needed. Plug it in to a device for a day/week/month and it will tell you exactly how much pow

    • But how would you tell if your meter is going backwards or forward? ;-) Great hack but it won't work for systems with grid tied solar electric systems. It's too bad because I liked that your system actually reads the power companies measured usage.

      If I could tell the direction, then I could take the difference between the solar generation and the amount of negative power usage on the meter. That would then be the actual energy usage.

      LoB

  • Automatic Marriage Conflict Device (Score:4, Interesting)

    by DanielMarkham ( 765899 ) * on Saturday July 16, 2005 @07:47PM (#13084030) Homepage
    This doesn't seem like much of a practical thing to me. After all, most marriages have difficutly when it comes to spending money -- do you really want minute-by-minute graphs of who uses what in the house? After all, the writer admitted that at the end of this whole adventure he managed to show that his computers were using more electricity than his wife's stuff. FTA
    Keep in mind that when it comes to friends and family, 'informative' is a relative term. Although you might find it very 'informative' to know that your wife left the lights on in the living room three out of four nights last week, she will probably not think so. I've found it better to save my geek points for things like "honey, don't you think we should have a raid server?"
    I don't find any of that informative. Or rather, I find it detailed information about something that is trivial. Even if you have very tight budget, do you really want to argue about who leaves the lights on the most? What's next, sensors to monitor where people are at all times, and correlate electricity usage? No. Count me out on this one. But I got to admit -- the software looks cool!

    NASA: Beats us [whattofix.com]
    • After all, most marriages have difficutly when it comes to spending money -- do you really want minute-by-minute graphs of who uses what in the house?

      I've always said that two people who keep score lose...
    • You don't find it informative to know which lights are left on most frequently? Think outside the box. Don't think about pointing the finger, think about problem resolution.

      Lights being left on wastes energy. Perhaps that room needs timed light switches that switch off automatically after 4 hours' time? Perhaps that room needs Compact Fluorescent Lamps instead of Incandescant in order to save power when they do get left on? Maybe both? It isn't about arguing over who is using more power, it's acknowledging

  • Does your home still meet safety codes? (Score:4, Insightful)

    by CyricZ ( 887944 ) on Saturday July 16, 2005 @07:48PM (#13084034)
    "while I had to rewire all my electrical to do it"

    Most areas have municipal safety codes when it comes to stuff such as wiring. Are you sure your wiring is compliant with such standards? Has it been approved by your local building inspector?

    • he rewired his house without killing himself, which proves to me he's smart enough to know to get it all inspected.

      • Re:Does your home still meet safety codes? (Score:5, Insightful)

        by CyricZ ( 887944 ) on Saturday July 16, 2005 @08:04PM (#13084113)
        Just because it is working now does not mean that it will be in several weeks, months or years. Such codes are in place to prevent home hackery like this, especially in the case of electrical wiring. The potential for his modifications to fail are astronomical. And if he did such modifications without proper inspections, then the situation could get very hairy were things to go wrong.

        Perhaps his insurance company would not pay him if it was found that his uninspected electrical modifications were the cause of his house burning down, for instance.

        • i thinkt he parent was suggesting that because he managed to rewire it all himself he cna't be stupid enough to not do it right with permits and the like.
          • While his site is now completely slashdotted and I thus cannot double check it now, I do not recall seeing any mention of such inspections while reading it. That is a pretty integral part of the plan, or at least would be if performed by somebody who is alert to such safety codes.

            I would have expected him to brag about how the local safety inspector was impressed by his system, or perhaps even how the safety inspector pointed out potential flaws that needed to be fixed. Indeed, I recall reading about neith
          • i know plenty of smart people who dont bother with permits/inspections when it comes to home improvements. it can be a hassle to learn code (if you dont know it) and to get someone down from the county that isnt going to say, "you did what with your wiring?" being said, you still should get those things sign off on.
            • Well, there's an awful lot of stuff in the NEC these days. As the technology of the components changes, and as best practices are improved upon by the industry, these are adopted into the modern electrical code.

              Smart people aren't always knowledgeable about other fields. As in computers, there are ways to make it work that don't necessarily mean they're done correctly. I was almost zapped earlier this year because I was working on some wiring in my sister's basement that had been put up by a previous o

              • That is sickening what you encountered in your sister's home. Indeed, I hope the future owners of this particular fellow's home do not fall victim to his electrical hackery.

              • For example, in the 1970s aluminium wire was legal for use in residential wiring, but it was later discovered that its coefficient of expansion was greater than that of copper, and that after years of expansion and contraction the wires could escape from underneath the screws that held them, causing arcing and fires. The code has been modified to explain how to handle existing aluminium wiring.

                In the US, at least. (The UK, for examlpe, never had this in homes). Of course, none of this applies to non-US

        • Re:Does your home still meet safety codes? (Score:5, Insightful)

          by ErikZ ( 55491 ) on Saturday July 16, 2005 @08:54PM (#13084310)
          Such codes are in place to prevent home hackery like this, especially in the case of electrical wiring. The potential for his modifications to fail are astronomical.


          I agree! Think of the dangers of brewing your own beer, working on your car, or even programming! Almost all viruses were programmed without any kind of government oversight.

          There should be codes that are enforced by the governemnt that touch upon everything you can possibly do. To protect you, and others, from yourself.

          Seriously, the codes are there to protect people from substandard wiring. But to insist that you have no right to modify the wiring in your own house is too "Big Brother" for me.
          • Sure he has the right to rewire his own house. In case you failed to notice, that is exactly what he did.

            Indeed, the safety codes are there to protect people from substandard or faulty wiring. That is why he should have gotten the local inspector in to check on it, and to verify that the modifications he has made are safe. It's not only the financially prduent thing to do (ie. in terms of insurance and preventing the loss of his hard-earned property), it is also the socially responsible thing to do. Not on
          • getting off topic here, but what happens to your "modifications" when you sell your house?

            Caveat emperor?
            • getting off topic here, but what happens to your "modifications" when you sell your house?

              Caveat emperor?

              I think that if an emperor were to buy your house, he could afford to perform his own inspections and rewiring.

              Perhaps you meant "caveat emptor".
              • Your point still holds: the emptor should have an inspection performed.

                It's my right as an American to burn down my house if I want to. Besides, what's the difference between faulty wiring burning down my house and a carelessly discarded cigarette doing the same? Should inspectors come by your house every night to make sure you're not smoking in bed?
                • It's not your right as an American to burn your house down, at the same time possibly killing your wife, your housekeeper, your children and potentially others (ie. neighbors, guests).

                • The difference is intent. Did you intend to burn down your house or not? Did you know that your actions would reasonably lead to the conclusion, or are you willing to admit publicly that you are just *that stupid*? Once having done that, then if you do the same thing again expecting a different outcome, you could be committed for insanity - if you manage to convince a jury that you were in fact not acting maliciously even with prior knowledge of the likely outcome on the record, which would suffice in ma
            • The new occupant is going to have to get a certificate of occupancy, where the electrical wiring (along with lots of other things) will be inspected. If the house was sold as is, then it's up to the new occupant to fix the problems. If not, then it's up to him to fix them. Either way, without a CO, the buyer isn't supposed to live in the house.
          • PERMITS? We don't need no STINKING PERMITS
            SCREW THE CODES AND ANAL-RETENTIVE CODES INSPECTORS!
            It's my house and my property I will do WHATEVER I want with it!
            In fact I Do! I have added on about 40% to the size of my house since I moved in about 16 years ago. I have done much indoor and outdoor wiring as well as plumbing. Installed a pool and Solar heater, as well as miscellaneous outbuildings. ALL without one single permit or inspection. Granted I live in Tennessee where freedom is still more than ancient h
            • Remind me never to move to Tennessee (not that I ever would, mind you). I'd much rather live in a city or township where inspections of homeowner (ie. non-professional) renovations, especially to potentially hazardous systems like the electrical system, are mandatory. I don't trust redneck cowboys to properly wire anything safely, let alone a house. It isn't a matter of "freedom" to get your wiring inspected; it's a matter of common sense dictating that any avoidable disaster should be avoided.

          • You pull your house off of the grid, and you can do whatever you want to with the wiring in your house.

            As long as you choose to attach to the public electric grid (privately owned or not, there is public interest in its upkeep), you have to accept some level of oversight of the things you do in your house. For example, if you chose to use equipment that had a really bad power factor (i.e. voltage and current were out of phase), the power company could and would order you to adjust your load. Or, if your
        • And if he did such modifications without proper inspections, then the situation could get very hairy were things to go wrong.

          I agree with you on codes - they are there to demonstrate good building practice and any smart person will consult them like a good reference book.

          But inspections - these are for the municipality to justify their permitting process, which is really to increase their tax revenue.

          The previous owners of my house were an old couple, by-the-books, they hired out everything and pulled e
        • Such codes are in place to prevent home hackery like this, especially in the case of electrical wiring.

          Actually building codes are mainly intended to guard against shoddy work by contractors trying to save a few bucks. The only enforcement focuses on getting occupancy permits and the like. Most building departments don't worry too much about stuff like this.

          I've done quite a bit of home electrical wiring, and I'm familiar with a lot of the code. It's mostly common sense stuff. While I can't speak for the
          • Exactly. Some municipalities impose fines for doing work without permits and inspections, and calling out an inspector sounds like a good way to get your power shut off until you undo all your changes and start with the permitting process from the beginning.

            I would pay a licensed electrician for an hour of his time to come out and inspect the work. While he wouldn't 'officially' sign off on it, he would be able to point out any glaring safety issues or code violations.

    • Re:Does your home still meet safety codes? (Score:4, Insightful)

      by kent_eh ( 543303 ) on Saturday July 16, 2005 @09:42PM (#13084492)
      From TFA:

      The current transducers are actually really small and they clip on to the wiring

      The power monitoring system is not connected dsirectly to the wiring. It is using inductive sampling.

      I serioisly doubt that having an inductive device near the conductor (outside the insulation) has any impact on the overall safety of his house's wiring.

    • Seperation of High Voltage/Amperage from Low (Score:4, Informative)

      by MonkeyBoyo ( 630427 ) on Sunday July 17, 2005 @12:13AM (#13084982)
      I am not expert on the details of various building codes, but I am familiar with the intent of electrical codes that try to prevent high voltage/amperage wiring from being in the same enclosure as low stuff. For example, codes encourage 120 V wiring to run through conduits but prohibit running low power lines (such as phone) to run through the same conduits. Why? Because some stupid accident might cause the wires to become cross connected and blow out devices or start a fire.

      Mounting an uncovered PCB (printed circuit board) that communicates with a computer within a 120 V distribution panel is a very big no-no. What if geek hubby is out of town and wifey experiences a power problem and calls in a yellow page electrician to fix the problem? In the worse case the "electrician" accidently drops a tool that winds up connecting 120 V to the computer circuits and starts a fire in the server room.

      Building codes are designed as protection from stupidity - not only the stupidity of the the original builders but from the stupidity of those called in to fix problems.

      To anybody who wants to do anything similar - it makes sense to put the current sensors in the distribution panel, but please rout them out to a seperate box that sends their info to a computer.
    • "Most areas have municipal safety codes when it comes to stuff such as wiring. Are you sure your wiring is compliant with such standards? Has it been approved by your local building inspector?"

      Well, I'm 99 and 44/100 % certain that he no longer has valid insurance coverage, even though he might think that he still does, and that the inspector would probably have a conniption fit if he ever actually saw that installation.

      If he just went out and bought a new panelboard because it was rated for enough amperag

  • electrical bill now? (Score:5, Funny)

    by AmigaAvenger ( 210519 ) on Saturday July 16, 2005 @07:50PM (#13084044) Journal
    great, you do all this to minimize your bill, then post on slashdot?!?! server is already slow, I imagine the meter is spinning like a top right now...
  • "About nine months ago the motor overheated on our dryer while the house cleaner was here. I asked her how many loads of landry she had done that morning and she said three. I took her back to my office and fired up the software and told her she had done four and wow, there was a significant current surge when the motor gave out. She was also not particularly impressed and she now asks me every time she wants to use something in the house (not a good thing)."

    Uh, can someone say backfired? Women.

  • Have to say (Score:5, Insightful)

    by zegebbers ( 751020 ) on Saturday July 16, 2005 @07:52PM (#13084055) Homepage
    Since I had all the hardware for testing, I figured what better way to test things than to install it in my own home.

    That's an awesome attitude that we don't get enough of on slashdot these days :(

    • Re:Have to say (Score:3, Informative)

      by elmegil ( 12001 ) *
      You're not really getting it on slashdot today either. This is basically horked [makezine.com] from the Make Magazine blog [makezine.com]. If you really are interested in that kind of attitude, you should read it instead of slashdot.
      • Not sure what your point is. If you're saying that Slashdot was six days late to the party, well, yeah, surprise surprise. But if you're saying the guy just aped a Make hack and then got it posted on Slashdot, no. The guy who wrote the article Make blogged is the same guy who wrote the Slashdot story you're reading right now. Both link to

        http://www.kondra.com/circuit/circuit.html [kondra.com]

        p
      • Why is this 'horked'?

        Sounds like David posted to both places...which is well within his rights to do. Seems like it was interesting enough for both places to post.

  • Very cool, but a potentially dangerous area (Score:4, Insightful)

    by Sv-Manowar ( 772313 ) on Saturday July 16, 2005 @07:53PM (#13084059) Homepage Journal
    The screenshots of the monitoring software in use and everything make this seem extremely cool, but the potential risks seem huge. Obviously from the article this guy has done this kind of thing for work and had all the right equipment. I'd hate to see the results of someone lacking these vital elements 'hacking' their mains power system to get pretty graphs. The website says as much in its disclaimers too.

  • Dome? What dome? (Score:3, Funny)

    by jfengel ( 409917 ) on Saturday July 16, 2005 @08:10PM (#13084128) Homepage Journal
    With the server already grinding to a halt and the "dome" left unexplained in the summary (is it some sort of euphemism?), I'll spoil the ending:

    His wife got ticked off, so to apologize he built her a ceiling dome (a recessed dome built into the ceiling, with a light fixture suspended from the peak). It looks nice.

  • Oh great.... (Score:3, Funny)

    by qwave54 ( 671614 ) on Saturday July 16, 2005 @08:14PM (#13084140)
    another piece of hardware looking to kill the meter reading industry!

    - Meter Reader

  • Network Power (Score:4, Funny)

    by Doc Ruby ( 173196 ) on Saturday July 16, 2005 @08:15PM (#13084144) Homepage Journal
    Seems to me that this kind of application should be integrated with "Power Over Ethernet" (PoE). Since every node on the network gets its power from the network, the adapter should collect this kind of data, perhaps in an embedded device with its own IP#. The same design logic for DC PoE seems like it should be true about AC "BPL", Broadband over Power Lines. In fact, those power/packet sockets should have cheap little embedded devices that not only report power consumption, but allow control of it via TCP/IP. Isn't there such a network/power platform available COTS?

  • coral cache links (Score:5, Informative)

    by AMystery ( 725537 ) on Saturday July 16, 2005 @08:24PM (#13084182) Homepage Journal
    Since I had to go look for caches, i thought I'd share.

    The article on house wiring. http://www.kondra.com.nyud.net:8090/circuit/circui t.html [nyud.net]

    Another popular article from the site on building a ceiling dome. http://www.kondra.com.nyud.net:8090/dome/dome.html [nyud.net]

  • Yeah (Score:5, Funny)

    by cynical kane ( 730682 ) on Saturday July 16, 2005 @08:26PM (#13084188)
    You don't mess with a woman with a Power Management System...

    (ducks)

  • power monitoring (Score:3, Interesting)

    by unix_geek_512 ( 810627 ) on Saturday July 16, 2005 @08:31PM (#13084216)
    Geeks unite!

    Why not take this further? Instead of just monitoring let's modify the system so that we can turn circuits on and off remotely as well as being able to monitor usage. In fact why not wire the whole house so that the lights turn off automatically if there is no one in the room unless the system is manually overridden?

    We all need to think about energy conservation and energy security which is a big part of our national security.

    I would encourage everyone here to build a system with occupancy sensors so that lights, appliances and devices are not left on unnecessarily.

    The occupancy sensor module could include PIR sensors, temperature/humidity sensors, smoke detector, CO detector, intrusion detector and perhaps a CCD camera all linked to a GNU/Linux system capable of controlling energy usage as well as calling the Police or Fire Dept. in case of an emergency.

    Live long and prosper
    • X10 sucks. It can only turn on and off.

      Would require an entirely new protocol, to do bidirectional data. I've considered such, but it's doubtful that the things would have any mass market appeal. I'm thinking a board the size of a deck of cards. z80 cpu, 32k static ram, 32k eeprom. Tcp/ip stack, over daisy-chained serial. You'd have a single cat running from your computer to the first module, and then another chained off the first, etc. Could even do power over the cat5, reduce wirepulling.

      Now, put 3 or 4
    • Instead of just monitoring let's modify the system so that we can turn circuits on and off remotely as well as being able to monitor usage.

      This is already possible. Many breakers can be bought with a shunt trip mechanism. Essentially, you provide a small current into the shunt trip, and it will cause the breaker to trip. So yes, you can turn the power off. If you want to turn it back on, you have to walk over to the panel.

      Are there breakers with two shunt trips, one to turn it on, another to turn it

    • Instead of just monitoring let's modify the system so that we can turn circuits on and off remotely as well as being able to monitor usage.

      You've clearly never tried to do this, because it is massively difficult.

      Nobody would ever suggest doing this for a private home, because the huge cost, time, hassle, and minor savings aren't worth it. (A large office building is a different case.)

      If you want to save energy, use (good) fluorescent light bulbs instead. They use as little as 1/10th as much power, an

  • Holy crap! (Score:4, Insightful)

    by pr0nbot ( 313417 ) on Saturday July 16, 2005 @09:24PM (#13084411)
    Surely the next news item has to be "slashdot editor reads TFA"!

  • Try designing an entire power network (off-grid) (Score:3, Interesting)

    by JimMarch(equalccw) ( 710249 ) on Saturday July 16, 2005 @09:24PM (#13084416)
    That's a whole 'nuther thing.

    http://www.equalccw.com/wiringdiagram.gif/ [equalccw.com]

    This is all going into the older motorhome I'm renovating :).

    Every watt going into and out of that monster 650lb battery (all $1800 worth) will be measured by the Bogart Engineering "Trimetric" device. It sits in-line with the battery negative terminal.

    http://bogartengineering.com/trimetric.htm/ [bogartengineering.com]

    The solar charge controller has it's own measuring system as does the inverter/charger but those can be mostly ignored - it's the Trimetric that matters.

    Note: "inverters" take 12v DC (or 24v or whatever size battery bank you're running) and convert that to 110v wall juice. Good ones deliver "pure sine wave" power like a very clean electrical outlet. An "inverter charger with pass-through" like my Outback 2812 will take any amount of incoming AC (utility grid, generator, whatever) and pass it through while also charging the battery at 12v in my case. When the utility grid or generator is cut off, it works in reverse, delivering 110v from the battery bank.

    My main inverter is this sort of inverter/charger. My secondary inverter is "just an inverter" and smaller at 1100watt, but it's completely isolated from what's going on at the other inverter - a major load like air conditioning or the washer/dryer combo can spectacularly puke and die over on the 2800w main inverter and it'll cause not a single glitchy on the 1100 inverter powering the computer gear, satellite internet, etc.

    Anyways. If I wanted to monitor all this with a PC I'd get the Bogart "Pentametric" with PC interface:

    http://bogartengineering.com/pentametric.htm/ [bogartengineering.com] ...but...why? :)
  • It would be kind of interesting to rate housing/apartments by power cleanliness.

  • I saw this the other day.... (Score:3, Interesting)

    by The Slashdolt ( 518657 ) on Saturday July 16, 2005 @09:48PM (#13084522) Homepage
    I saw this the other day as a reference from Make magazine. I looked into the hardware and that circuit monitor alone is over $2000 USD. Be aware that this setup is quite costly. Notice the update on the first page that says he is trying to get the company to provide a lower cost version.

  • It would be great if appliances and lamps summed up their own electricity usage over time. All that electricity comes to us by giving a ton of cash to those people who'd prefer to bomb us or raise our oil prices. Minimizing electricity usage is a good idea.

    I've significantly used my electricity costs over the past year just by changing my habits. This guy [blogspot.com] went a bit further and saved even way more than I did. Impressive.

  • mandatory wtf.... (Score:4, Funny)

    by Anonymous Coward on Saturday July 16, 2005 @11:59PM (#13084941)
    Hardware: Zero dollars
    Software: Zero dollars
    Linux box: Zero dollars

    Explaining to your wife that after hours of development you've built a device that proves the most power hungry appliance in your house is the damn power monitoring system itself: Priceless
  • Results in a 404. /. effect already?
  • on /. It's so fucking great. I have to do this at my house. Seriously though I think that this guy is onto something. If you had some kind of standardized panel you could build the CTs right into the circuit panel. Then you could hook them up to a dedicated controller to give you the information. Or perhaps you could build smart outlets that had a built in TCs in them like a smarter X10 outlet. I think people would buy this, energy consumption is becoming more of a concern for many homeowners.

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