Efergy E2 Energy Monitor

I recently received the below email from Lyn Chapman of Chapman Specialty Equipment & Inspection.  It seems that the Efergy E2 is made by a U.K. company and Lyn is based in Ontario, so I'm not sure how it would perform in the U.S., but it definitely looks like a good product has the potential to be a good product (see my update below for clarification).


I was asked to conduct an independent evaluation of energy monitoring products for my company. I looked at numerous products and purchased the Black and Decker whole house Energy Monitor (which uses the same technology as the Energy Owl) , the TED 5000, and the Efergy E2. Here in Ontario we quickly found ourselves dead in the water with the Black & Decker unit as the majority of meters used by the various utilities are not compatible with the technology utilized for the device.

The TED 5000 is a good product but we found issues with the powerline communication system used with the devices. This required us to come up with solutions to make it work which included spending additional money on noise filters, installing dedicated breakers for the MTU's and locating the gateway close to the utility panel.  We then encountered the expense of running cable to the modem from the gateway location and this also limited the communication range of the remote monitor.  On the issue of the remote monitor, the first one sent to us was defective and would not work at all.  While the replacement monitor does work, it does not communicate everywhere in the building that we would like.  We were also unable to get the Google Earth feature to work.  TED support advised us that their Google Earth feature is not supported by all ISP's in Canada so we would have to sort that out with our individual ISP. In Ontario, the TED 5000 units have to be installed with a permit and then inspected by the Electrical Safety Authority, all at additional expense.  While we landed our TED 5000 with 4 pairs of Ct's and the remote monitor here for around $520.00,  by the time we had it installed and working,  we were over $1200. deep.

The Efergy E2 is also a good product and we found that it was capable of doing everything we needed including the collection of historical data and making graphs. The unit was quick and easy to  program, easy to install, and the wireless radio communication worked flawlessly. There was nothing else to buy, no permit to purchase, no electrical contractor to involve, just 30 minutes of my time and we were in business. We now have over 40 of the E2 units in service at our various client locations, all without a single glitch.  We have been purchasing our units from a company in Florida  at

It is worthy of note that I was on a training course with Schneider Electric in Toronto a few months ago and an Engineer in the class from New York was expressing his concerns to me over the communication problems he had been experiencing with his Energy Detective. I told him about our experience with the Efergy.  After returning to the United States, he purchased and installed four E2's from Florida for his own use and that of his family. He has been absolutely delighted with the Efergy E2's he purchased.

I am advising you of this information as I believe that you would do your readers a great service by including the Efergy E2 in your product line up of energy monitors. These are difficult economic times and the Efergy E2 sells for about half the price of an Energy Detective. When it comes to monitoring energy, the E2 does a fantastic job.  I typically install an E2 in our client locations in less than 30 minutes including programming.  The Efergy E2 is also available for 3 phase installations.


***Updated - 4/17/10 - I had a reader write me with the following comment: "I looked up the install info for the Elite and Elite 2 Efergy systems. They don't have a voltage connection and therefore do not sense voltage. Voltage is entered in the display. These are really current meters that don't measure kw or even volt X amps. The accuracy will be very bad with motor and transformer loads. Also inaccurate with voltage changes. The TED and also the ECM-1240 family (Brultech) are true kWh monitors."

And it seems that he is right.  I found the install instructions on Efergy's website here.  The instructions state:


Press and hold Mode Button for two seconds. Default voltage is set at 240V. Use BWD and FWD buttons to change the voltage. Press MODE Button to save your setting and move into currency selection setting.

And so if your voltage never varies, you will have accurate power consumption data, but if your voltage does have a problem.  How does the Efergy unit differentiate between 240 V loads and 120 V loads?  For example, most U.S. homes have both.  Your toaster or TV runs on 120 V, but most electric clothes dryers and AC units run on 240 V loads.  If you have to manually enter voltage into the Efergy unit, how can it determine total power consumption if you have your AC unit (240 V) and your TV (120 V) operating at the same time?  The Efergy unit will read total current flowing through your wires, but the total power consumption it tells you will either be too high (if you entered 240 V into the unit) or too low (if you entered 120 V into the unit).

***Update - 9/3/10 - My original issue was solved, so I crossed out the text, but it is important to note that in U.S. installations, you must set voltage to 120-130 V!

***Update - 4/28/10 - Thanks to the help from Lyn and Juan from Energy Monitoring Technologies I have the Efergy InstallationSupplement-US & Canada.  In US installations, the Efergy unit uses 2 current transformers to measure current on both legs of the residential electrical service.  When a 240 V load is operating, it is merely pulling power from each of the 120V leg and adding the current from those two lines together in its logic.  For instance, your 240 V appliance may see 5 Amps at 240 V (1.2 kW) , but the Efergy meter will be recording two, 120V/5A loads (120*5 + 120*5 = 1.2 kW).  For all intensive purposes, it doesn't matter if a meter measures 4 Amps at 120 V or 2 Amps at 240 V, the math will come out the same.

But conservation isn't the only area where  a problem can occur.  Clean energy installations could also pose an issue.  The voltage on a solar panel array will fluctuate throughout the day based on how the inverter regulates the Maximum Power Point.  Basically, the inverter will fluctuate the solar array's voltage output so the power is alway at its maximum.  If the voltage fluctuates, the Efergy unit is going to be unreliable!

***Update - 4/20/10 - Thanks to some helpful comments below (thanks Lyn, Suzi, Juan, others) I'm not so worried about the accuracy of the Efergy meter, but I would like to hear about people who have tested the Efergy's accuracy against their residential meter or used it to monitor a solar panel installation.  See Lyn's comments below about where he sets his voltage setting at.

enjoyed our post? let others know: 


Hi Tom, Im curious if I have a solar system installed with Enphase microinverters pushing AC back on to the grid, if that will have any effect on the E2 readouts? thx
Thanks Tom. Looking forward to seeing more news about the Efergy in the U.S. From what I've heard it's a great product!
I received my Efergy e2 a few hours ago and posted an unboxing video on my blog: It does have 2 sensors, one for 120v, and one for 240v. It seems to work fine, but I'm not clear what voltage I was supposed to pick during setup. I went with 130 due to someone's comment above. I'll provide more video and details once I've played with it a bit.
Thanks for the update Peter! Have you seen my earlier blog on the monitors that you make: I do point out some of the shortcomings that I see (no software that enables users to export data) but I do think it is a great product for those who don't need to export data and have the right meter. Thanks again.
I just ordered an Efergy E2 from I'll provide updates once I've received it.
Juan, You do not need access to you meter, you simply have to take the cover off of your breaker panel in the apartment. Every bit of power you use goes through the two main wires in that panel. Simply connect the transformers there, and connect the voltage wires to 2 breakers next to eachother.
Dear Jay: I have provided two posts to address issues raised by other Mapawatt readers which may be helpful to you. The Efergy site in England is excellent, but it also deals with typical installations and programming of the meters in Europe where there is no neutral and everything runs on 240 volts. There are software differences between the Efergy meters being sold in Europe as opposed to the north american market. We do not sell Efergy meters in the United States, however they may be purchased in the U.S. from Energy Monitor Inc. in Florida. Their web site is at One thing is for certain Jay, unlike the problem you encountered with the Black & Decker Power Monitor, the Efergy measures energy independently and separately from the utility meter. If you have power going into your home with a service rated at 200 amperes or less, the Efergy will work for you. Here in Canada, we only sell our Efergy E2's with two Ct's for single phase applications. In order to accurately measure power consumption on both sides of the single phase line in your home, be certain to order your meter with 2 Ct's from the American web site since the Efergy is also available in the U.S. with a single CT. If you have any other questions, please feel free to contact me in Canada or Energy Monitor in Florida. Thanks Suzi Beck Technical Support Rep. Energy Monitoring Systems Canada e mail: web site:
Dear Chris: I would like to respond to your reader with regards to his concern about voltage and current flow. This is a question that I have dealt with in the past and at the end of the day, the proof is in the actual performance of the Efergy meter. Your readers need to clearly understand this because marketer's of more expensive meters claim that less expensive meters may be out by as much as 50% from the utility meter. I have no argument whatsoever that meters which use reference voltage supplies will, in adverse conditions of fluctuating voltages, produce a more accurate reading than a meter with a programmed voltage set point, such as the efergy uses. We at Energy Monitoring Systems Canada are serious about providing accurate, cost effective, energy monitoring solutions for our customers that are simple to install and easy to use. When we first looked at the efergy, we noted that there was no voltage reference source for the meter. This being said, journalist from all corners of Europe wrote terrific overall reviews on the Efergy and over 300,000 Efergy E2's were sold in the European Union alone in 2009. With this in mind, we purchased the Efergy E2 and carried out our own testing. On the same 200 ampere electrical service, downstream of the utility smart meter, we installed three pairs of CT's for three different meters. These included, The Energy Monitor Inc. EM2500 with a reference voltage supply and a stated 1% accuracy in energy monitoring. An Energy Detective TED 5000 with a reference voltage supply in the MCU connected to a DP breaker in the service panel. An efergy E2 with no reference voltage supply. Since we are in a rural area with higher known voltages, for the purpose of our testing, we programmed the reference set point in the microprocessor at 130 volts to neutral. (The E2 uses two Ct's for a standard single phase installation and in north america the set point is programmed with the voltage to the neutral) Over a period of a week, we monitored the readings on all three of the meters simultaneously. Typically, at any given time, with an average reading in the 1.2 to 1.4 kw range for the house, all three meters recorded energy consumption up or down within 10-15 watts of each other. Even the EM2500 and the Energy Detective disagreed within the same range at any given time. At the end of the week, all three meters agreed with the reading on the utility smart meter that a total of 267 kw/h of energy had been consumed over the 7 day period. Since the utility voltage reaching homes in North America is largely stable, the kw readings provided by a meter such as the efergy are going to be credible and accurate for the purpose of monitoring the use of electrical energy in homes and small businesses. While the efergy will not be as perfect as more expensive meters in areas where the voltage flucuates a lot, as in our test case, we knew that our base voltage is higher than normal so we simply programmed to meter to compensate for the higher voltage achieving accurate results. In closing, I can say that I have not received one single complaint from any customer about the accuracy of their efergy meter. Thank you for giving me the opportunity to comment on this issue. Suzi Beck Energy Monitoring Systems Canada Technical Support Rep.
Hi Jay: Thx for the update. I am certain that you will not be dissapointed with your new meter. I purchased another 25 E'2s last month for my customers. I find the meters record almost spot on if you program the voltage set point to 130 volts as opposed to 120 Volts. I am doing testing all the time with a variety of meters, but I did yet another experiment at my home on Saturday because of all the concern on Mapawatt about flucuating voltages affecting accuracy. Before I left for the day I took readings from both my efergy E2 and my smart meter outside. I live in a rural area known for both flucuating and higher than normal utility voltages. When I arrived home that night I took readings from both meters and they agreed that 33 kw/h of energy had been counsumed during the day. (My wife also did the washing and drying while I was gone for the day). You may wish to look at the great technology web site and forum page in Australia where the Efergy line of products migrated early in 2009. There is a forum regular on the site much like Chris is to Mapawatt. I have pasted one of his comments on the efergy below that talks about the programmed voltage set point. Breno's comments are spot on in my view. In my own testing, I have not found the use of a programmed voltage set point to be an issue that results in any kind of significant problem related to accuracy. User #268784 80 posts SparkyBreno Forum Regular I can highly recommend an Efergy E2, it's not perfect as it only measures the current and converts to kwh with a preset voltage but for what it is and the awareness it creates it's brilliant. The best feature is uploading all the data to your computer (Windows only ATM) and being able to see lovely graphing on usage patterns etc.
Derek: I would like to provide some clarification on the installation of the Efergy Energy Monitors. In the U.S. and Canada, the Efergy units are installed at the electrical panel, inside a home or apartment. The units sold in the U.S. and Canada come with the installation diagram for installations in the U.S. and Canada. You may have seen a diagram of the installation in Europe, which shows cliping on a power wire from the electric meter. The Efergy E2 comes with a USB connection to download the data to your computer. At the present time there is no web interface. If you have any other questions, please do not hesitate to contact me. Juan Gonzalez Energy Monitoring Technologies, Inc.


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