A few years ago I was shopping for some sort of data logging electrical system monitor and came across some really interesting solid state units that could monitor supply and usage over time. They had a USB interface that would allow them to be plugged into a laptop to download the data for analysis. Does anybody here know of such an animal? I would think that this sort of tech would be becoming very affordable and available but just don't know where to look.

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You can monitor 120v plug loads with a Kill-A-Watt, 240v loads with a TED or similar, or do circuit level monitoring of entire electrical panels with systems from Powerhouse Dynamics, Brultech, and others. A good site to check out is Energy Circle http://www.energycircle.com/

Peter, is your objective personal or an offering for customers?  After the first run through what each appliance uses I have found it unnecessary to continue monitoring them.  And, the initial use can in most cases be simply estimated.  My only use for my meters has been an occasional search for something using too much, but I have in each case found the problem without the meter, a heater left on or a motor running continuously.

With my electrical background I thought it would be a neat addition to my service offerings, but my return on investment has been negligible.


If the customer has a smartmeter installed by the local utility they may be able to get whole house usage data on-line for free.

Last one used was power house Dynamics.   Its for a home owner and data just went back 30 day only.   with USB port you can use most programs,  If use use one of the free on line it can do yr by yr.    I put in a Ground Type Heat pump with just one tank and a desuper heater and I have proof that you get 0 from the AC side  after the buffer tank is put in you get 30% savings.   I have proof  If you set the temp on the tank to 150' then to 120' it goes to $140 mo to $55MO.   I have proof if you set a solar hot water tank and only use hot water only in early AM  you have no saving Use hot water in mid day and it all there - just stand by loss.  I learned a lot with data loggers its real for that job. its a must!

Wow, sorry, got busy for a couple of days there.  I was looking for something that taps in at the first panel that would monitor power conditions as well as load over time so i could have an idea when there are voltage spikes and how large, if certain appliances were turning on excessively frequently or getting noticeably less efficient, etc.  The data logging aspect was for the purpose of being able to map summer versus winter usage patterns, occupied versus vacant patterns, changes in usage with changes in infrastructure and other utilities, but mostly because I have a lot of energy hog clients who always want to know why their electric bills are so high on their multi-million dollar homes and they refuse to believe that it simply costs more to run a larger home, whether or not they actually live there.  Data with real numbers from which I could generate charts would be extremely useful and definitive.  I have a couple of Kill-A-Watt meters and they are very useful for certain kinds of short term testing but i also have a clamp on multi-meter that i always have to carry anyway and with a special pigtail I fabricated and the calculator in my smart phone I have found the Kill-A-Watt to be redundant.  

     Thanks for all the tips, I'll be doing a little research now to see what I can use, I'll report back what I find.

if you create a database with all things electrical and a column for ratings and measured power consumption, you will be able to accumulate information over time that will make your job easier and more accurate. With that database or spreadsheet you can estimate hours of use per month and get an overall estimate for each home. It is when that estimate does not correlate to their actual bills that the meters must come out. What you will discover is that only the big things count so the list of what needs to be tested gets much shorter. In reality, you will get good enough to not even need the data loggers 99% of the time. Yes, they will provide documentation, but they will also require a lot of time. The spreadsheet will help to eliminate billing them for finding nothing out of the ordinary. And if you find the problem without the data loggers, that is all they wanted in the first place.

It is my contention in most of these cases that there is nothing out of the ordinary going on but the clients insist that some kind of "power surge" seems to have fried some equipment of theirs, or there is some mysterious load sucking up there KWh. Estimating hours of use per month sounds questionably accurate. How do I estimate how long the water heaters are on per month? I thought with monitoring equipment I could remove some of the guesswork. Understand that these are not people who are concerned with how much they are paying me, I've had to get over that. You've heard the expression "penny wise, pound foolish", well far be it from me to tell them they should spend their money on someone else's time.

Definitely a different customer group as mine have always been looking for savings.  And that is one of the reason why most would be unhappy.  They would end up paying me and still have the high electric bills.  And still believe there is a problem somewhere regardless of how I produced my conclusions.  A real time monitor that they could purchase and watch might keep them busy, but running back and forth to install/remove equipment doesn't make many happy.

With the database, they can do an inventory or I can do one.  A few minutes discussing run time and plugging in standard guesses where necessary and up pops an estimated monthly bill.  If it is way out of line, a second run through (fine tuning) the numbers and you get closer.  Surprisingly, you have to be way off to move the monthly numbers much.

I admit measuring helps to improve your confidence in your guesses, but after you have done a few, the guesses are much faster and close enough.

Now commercial customers are another issue.  Unfortunately an Energy Auditor in Maine cannot touch commercial work without an engineering degree.  But I have helped a few small customers, no charge, and their bills are huge.  A small restaurant was running $1,200 a month when the AC was running.  They also get hit with peak demand.


You need circuit level monitoring for most of what you're talking about. You can monitor multiple loads over weeks or months and give them a web portal to look at cumulative usage for each load in their house. A lot of people want to know "where did all the electricity go?" and this is how you answer the question. A clamp meter in the panel only gives you a snapshot at a certain moment in time. Who knows what turned on or off after you left?

Power quality issues such as spikes are totally different, but I suppose it would be easy to monitor for that also.

Yes, circuit level monitoring would be great but even monitoring feeds on a given panel could be useful. For example, a refrigerator turning on or off could easily be distinguished from a water heater turning on and off and if the refridgerator is using more than its rated load, you could suspect something was wrong.
I had recommended to this one client when he was replacing water heaters to put in LP on demand water heaters (no NG, already set up for LP) but he instead chose to install 90gal electric storage heaters. His decision really stumped me as he is rarely on premises even 2 months in a year. A year later we found out he was only being charged for the lowest demand of his 3 electric meters. Now he has the care-taker turning off five breakers at a time for 24 hours at a time as I look on in amusement. I'm just trying to get ready for when that plan is abandoned.

How much detail do you want?  Kill-A-Watt can give simple loads, TED gives better details (but they can be flaky), there are multiple vendors with devices like the TEDs (The Energy Detective).  If you choose a device that can provide volt, amp, and phase angles at second intervals - it is actually possible to detect and disaggregate the  power data and identify individual loads as they start and stop -- with only a few current transformers.




Also google/bing  "electric power meter monitor for home" and you'll find lots of possible sensors.

Many of the home automation dealers carry the devices.  Now days you can get internet ready devices, zwave, bluetooth and zigbee... just depends if you want off the shelf complete solutions or something you intend to build on.

http://aeotec.com/z-wave-home-energy-measure  <-- an example


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