Power Plug Meters Help Save Money, Energy

With the ever-rising cost of electricity, we're all getting increasingly sensitive about how much power our computers, televisions, appliances and other doohickeys are using -- not just when we're using them, but also when they're allegedly turned off.

Some, like refrigerators, aren't running full tilt all the time. Others, such as computers, printers, displays and other gear, have "sleep" modes -- they power down significantly but they're still on. And some devices, like televisions and cable boxes, aren't really off when we push that "Off" button or switch. All are still drawing a small amount of power, a phenomenon that's called "parasitic load."

So how do you measure how much power you're actually losing to this load?

For home users, the electric meter outside the house shows how much total power is being consumed, but trying to watch that meter for changes when flipping the appliance on and off is challenging at best. If you're running an IT computer room or a data center, there are the new Power Distribution Units, like Raritan's Dominion PX family of devices, that can monitor power consumption down to the outlet level and toggle power to outlets individually. But devices like the 20-outlet, $1,249 Dominion PX are outside the budget (and needs) of a consumer.

Your alternative: a power plug meter, also called a "plug load meter."

A power plug meter sits in between the power outlet and an individual device and displays how much power (load) the connected device is consuming at the moment. It can track power consumption during a connected session, and calculate kilowatts and dollars per day, week, month or year. This function is important because, unlike something as simple as a light bulb, which operates for a set amount of time and always uses the same amount of power, many of our electrical and electronic devices use varying amounts of power.

Today's power plug meters can also track the minimum and maximum power draw in a session. Some even show the line voltage and monitor and track other aspects of power quality -- helpful in diagnosing problems and determining where you may need power protection accessories.

A power plug meter also should be able to tell you the device's power factor, which is calculated using factors such as the capacity of the circuit, and its current and voltage -- and is what your electric company uses to determine how much you're going to be charged.

Having all this information can help you decide whether it's worth turning off or unplugging your TV, desktop or cordless phone when it's not in use -- or whether your current device is a power pig and should be replaced.

To test how well power plug meters work, and whether they can really help save power (and money), I looked at three devices: P3 International's Kill A Watt EZ, Electronic Educational Devices' Watts up? Pro and Brultech Research's Energy Consumption Monitor/Logger ECM-1220.

All three devices measure 100-volt AC devices (i.e., anything you would plug into a wall socket in the U.S.), and two of the three can also measure 240-volt appliances like electric stoves and dryers. They offer basic information such as current power draw in amps or watts, session cost and monthly cost. They also provide tech/diagnostic data like minimum and maximum power draw; and all three measure the power factor.

Which power plug meter should you buy? Here are my thoughts.

Kill A Watt EZ

The Kill A Watt EZ power plug meter from P3 International is, at $60 list, the least expensive of the three tested here. It's also the easiest to use.

At 5 by 2.25 by 1.5 inches, the Kill A Watt EZ meter is about the size of a double-thick Palm PDA. It plugs directly into an electric outlet, which you would think was highly convenient -- but not necessarily a good location for it, however.

Although the numbers on its one-line LCD display are moderately large, the labels that also appear on the LCD (such as time, volts, cost, etc.) are small and hard to read if you don't have good eyes. In fact, if your vision is less than 20/20, you may want to connect the Kill A Watt EZ to your outlet via a short extension cord, so you can more easily see the display.

The Kill A Watt EZ has five rubberized buttons: Menu, Up, Down, Set and Reset. It has built-in battery backup , so it will retain current information when unplugged.

The device calculates cost per hour, week, month or year, easily toggling the amounts for the various time periods. The Kill A Watt EZ's kilowatt and dollar displays have only two decimal places -- so the displayed reading on a low-wattage device, if it's a subpenny reading, looks like zero.

This is rather alarming, until you realize that the Kill A Watt EZ is actually capturing the data. As a result, if you want to check your power costs on a low-power device, you're probably better off looking at the per-month or per-year values.

Kill A Watt also offers a power-strip version, the Kill A Watt PS ($99.95). With this version, you also get six regular outlets and two wide outlets. In addition, it's at the end of a 6-foot cord, making the readout possibly easier to see.

However, the Kill A Watt PS won't do the cost calculations, nor do per-outlet measurements -- you're better off plugging a power strip into the Kill A Watt EZ.

If all you're looking for is basic power usage and costs, the Kill A Watt EZ will do the trick. Just get a short, heavy-duty power cord, and remember to toggle the cost-per-period if you're seeing $0.00 as your power cost.

Watts up? Pro

Electronic Educational Devices' family of Watts up? meters includes the Standard ($96), Pro ($131), Pro ES ($196) and .Net ($236). The latter is getting out of the impulse purchase range, but the added capabilities, if you want them, can make it a bargain.

The Watts up? Standard, as the name suggests, is the basic model, capable of measuring and calculating power usage, but without fancier features like logging readings or the ability to upload logged records to your computer.

The Watts up? Pro and Watts up? Pro ES include internal EEPROM (nonvolatile) memory for logging, and a USB port allowing download captured or real-time data records, viewable as records, or report and graph displays. You can track not just a device's power usage, but also power quality. In stop/overwrite mode, the Watts up? Pro can hold up to 32,000 records of watts reading; in automatic mode, recording all parameters, it retains about 4,000 records. The Watts up? Pro ES will hold four times as many records.

The Watts up? .Net has all the features of the Watts up? Pro ES, plus several that make it especially useful for IT and for support techs, such as a built-in Web connection, Ethernet port and power relay.

I tested the Watts up? Pro. The 6-foot built-in power cord made it easy to plug the meter into an outlet and still be able to read it and hit the buttons. And unlike the Kill A Watt EZ, the Watts up? Pro displays pricing down to tenths of a cent.

With only two buttons, Mode and Select, and 18 distinct pieces of data you can choose to display and/or reset using these buttons, the Watts up? Pro is much less user-friendly or intuitive than the Kill A Watt EZ. And there's no menu, instructions or other summary on the front of the machine, just the "Select" and "Mode" button labels, so you have to remember or guess what's what and how to get to it.

There are printed instructions and a one-page reference chart summary (PDF), but these include action/item numbers that don't actually appear on the Watts up? meter or display. This led me to initially set my cost-per-kilowatt setting incorrectly, which I didn't notice until I became suspicious of the way-too-low cost/kilowatt readings.

The Watts up? Pro meter starts a fresh session every time you unplug it from the wall, and you can reset the session manually.

The Watts up? Pro very badly needs a clear, separate "session start" reset-readings-to-zero button, or a serious UI overhaul. However, with practice, and the summary sheet, it's not too hard to get the hang of using the device. Watts up? Pro includes Windows software to download and display logged data; a real-time version is available for $79. If you're not a Windows user, there are links to user-developed Mac and Linux versions online. Also available online is a (Windows-only) Logging Interval Calculator spreadsheet calculators.

Brultech ECM-1220 PKG

The family of Brultech Energy Consumption Monitors (ECM) includes portable kits for home users and for energy professionals, as well as permanent wall-mount models, intended for monitoring an entire breaker panel. The main differences between the devices are the accessories they come with and their color (the meter meant for home users is white rather than black). Otherwise, the meters are the same.

Brultech's consumer-oriented ECM-1220 PKG and ECM-1220 Plus meters can be used as a power plug meter, like the Kill A Watt EZ or the Watts Up?, and also to measure devices that don't have plugs but are instead hard-wired to your power, like sump pumps, dishwashers, ceiling fans, furnaces and breaker boxes. It can also be used with devices where the plug may be inaccessible, like a refrigerator backed into a wall.

To measure power usage, the basic Brultech unit uses a current transformer (CT) clamping loop that goes around one wire of a power cable of whatever you want to measure, and a potential transformer (PT) that looks like an AC power adapter.

For devices you plug in, the wires in the power cable aren't individually accessible, of course. So to let you use the Brultech as a power plug meter, the company includes a Wall Plug Adapter (WPA).

You put the CT around the WPA's loop (like a hiker's D-ring), insert the plug from what you want to measure into the wall plug adapter and then plug the wall plug adapter into a power socket. You also have to plug the PT into the meter. Once you've got all this straight, it actually only takes a few more seconds than the Kill A Watt EZ or Watts up? meters, but does mean you've got more parts to track.

Because of the way it does its power monitoring, the Brultech meter (unlike the Kill A Watt EZ or Watts up?) may require calibration and setting before you can put it to use, but unfortunately, this calibration how-to information is hard to find and sort out. The keys are not well labeled, making calibration even more difficult. And although you can set the number of days to project use/cost, the display doesn't include that number on-screen, making it hard to remember what the calculation period is. (The Kill A Watt EZ and Watts up? remind you.)

To further complicate matters, Brultech's Web site (as of mid-August), was badly organized; notably, the 1220 PKG kit, although intended as a home/consumer product, was categorized as a professional product. (I've already passed this criticism along to Brultech, it may have been corrected by the time you read this review.)

The Brultech EMC 1220 can be connected to a computer for data downloading or for real-time monitoring, using optional software add-ons (it charges $59 for either of the add-ons, $89 for the pair).

Unlike the Kill A Watt EZ or the Watts up?, The Brultech ECM meter can measure two 120-volt devices concurrently or it can measure one 240v split-phase load, like an electric stove or electric dryer. With optional current clamps, it can be used to measure larger single-phase or split-phase loads with optional 150Amp or 200Amp loads, like the breaker panel for a house.

The Brultech ECM-1220 is useful if you want to measure something that's hardwired instead of having a plug, or where you can't get to the outlet, like a dishwasher or electric stove, or want to measure an apartment- or house-level breaker panel. If, however, you just need a power plug meter, at $249 and up, the Brultech is both too expensive and too complicated.


All three of these meters handle their core task: measuring and displaying how much power Doodad X is chowing down. None of them are as consumer-friendly as they could or should be, but they'll do the trick until a better product or new model comes along. One thing to be careful of, in all three cases: Be sure to check the math on your power costs, in case you set the rate wrong.

There really is no "best" among these three meters -- which you choose depends on your specific needs. If you're feeling frugal and simply want to get a power-consumption reading, get a Kill A Watt EZ. If you want to upload your data to your computer, the Watts up? Pro is best. And if you need to test devices with plugs that are inaccessible -- or that don't have plugs at all -- it's time to get a Brultech ECM-1220 PKG.

Whichever meter you choose will pay for itself over time.

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