Comments on: Kill-A-Watt Electric Usage Monitor Review

By: 2stepps

2stepps — Fri, 29 Jul 2011 21:06:45 +0000

Also Posted at: http://electronicdesign.com/Blogs/Communique/tabid/731/entryid/182/Default.aspx
What needs to be done is have someone run an experiment. Take four Kill-a-Watt (KAW) metering devices with battery back up, One power strip with out surge suppression, one power strip with surge suppression. Two manual vacation electrical timers. Four table lamps or floor lamps two with CFLs and the other two with incandescent bulbs. Plug the lamps into the KAWs then plug 2 KAWs into each power strip one CFL and one incandescent into each. Plug the power strips into the timers then plug into a wall outlet.
Set the timers to cycle on and off, on for about 3 hours and off for an hour, throughout the day. Then let them run until one of the lights burns out. Then compare the total electricity used and the cost of replacement light. Probably will be the CFL since they last longer being on instead of being switched on and off. You can also simulate them being in a bathroom by cycling them on for 15 to 30 minutes and then off for 30 minutes to an hour. Do that for during the day and then leave on overnight as a night light. This will give a good indication of which is better in terms of usage.

By: Leo

Leo — Sun, 26 Jun 2011 00:09:24 +0000

I really appreciated you explaining how the kill-a-watt is to be used, I tried the manual and was a bit lost , it doesn’t explain the amt. used divided by the time very well. I like the meter, maybe you need to explain things for them in the future, considering the popularity and how times electric companies have used this to show people how to figure this. Thank you, I shall use this for quite a while.

By: Luke C

Luke C — Mon, 11 Apr 2011 10:45:33 +0000

Let us know how that goes vinnie!

By: T. Boone Vinnie

T. Boone Vinnie — Thu, 24 Mar 2011 16:33:08 +0000

It’s the power company that’s gouging us. Ever notice the month after Christmas how high your electric bill is regardless of whether or not you ran Christmas lights? I am convinced the meter has a device built into it that is reset by the meter reader. Why else would the electric company not have gone to remote meter reading like the water company did so many years ago. I got into a telephone argument with one of the electric companies representatives a few years ago over the fact that my meter was old and needed to be replaced. Eventually the argument became heated and he told me that he wanted to fight me and would be down my house later that day. I told him to bring it on. He never showed but my meter was replaced a few weeks later with one that I swear gives the wrong reading every other month, showing up in my electrical bill. I was once charged over 10,000 kilowatts! I live in a fifteen-hundred square foot non electric house. I told the electric company but they were no help. They want me to prove that their meter is not working correctly by paying an independent electrician of their choice to come out and wire some device to my incoming lines to see how much power I’m consuming in a month. I asked if I would be reimbursed for the electrician and the past billings if their meter turned out to be wrong and the person said no. I don’t have the three-hundred dollars to prove them wrong and probably be lied to in the first place by their selected electrician. They will not believe any other independent electrician except the one they choose. I’ve purchased the 4660 to conduct my own test. It may take me a year but eventually I will have my proof and then I’m going to hire an attorney.

By: Bob

Bob — Thu, 10 Feb 2011 17:04:09 +0000

To cristina lazaro
The .0917 number is the electric rate from your electric bill. A 1000 watt load run for 1 hour will cost you $0.0917 or 9.17 cents.
As for your spa 120 volts X 11.7 amps = 1404 VA or 1.404 KVA
kill a volt amps. If it were a purely resistive load that would be the same as the watts. But sens it is a spa that involves a pump which means an electric motor. An electric motor is an inductive load. To find the actual watts you will need the power factor. That will normally be printed on the motor data plate. It will normally look something like “PF .86″ although the number will most likely be deferent. Once you have the PF you are ready to proceed.
120 volts X 11.7 amps = 1404 VA X .86= 1207.84 watts X the hours you normally run the spa example 4 = 4831.36 watt hours or 4.83136 KWH X the rate that you pay from your electric bill $0.0917 = 0.44303 or $0.44 per day X 30 days = $13.20 a month if you use it every day. Otherwise X the actual number of days you use it in a month. The Kill-A-Watt just solves all the math for you and tracks actual Volts, Amps, Power factor, Watts.
Sens it can vary from the data printed on the motor.
Hope this answers your question.

By: cristina lazaro

cristina lazaro — Thu, 10 Feb 2011 07:39:03 +0000

I am trying to figure out how to find out what my spa costs, it is 120v 11.7 amps and 60 hz.
and where did you get the .0917 number above? Just curious cuz i was trying to apply your formula to my situation! thanks.

By: Bob

Bob — Fri, 31 Dec 2010 05:30:05 +0000

Well it is funny to sit and read all the comments that everyone has left regarding the Kill-A-Watt. first of all let me just say that I am an Electrical Eng with 30+ years in the business. Let me just point out a couple things. First of all these little meters are quite accurate and they will remain that way for many years I have 2 of them and the old one that I have had almost sens they first came out is still with in one digit +- of the new one that is only about 2 years old. The intended use of this instrument is to give an indication of real time power draw. For most devices this this is a relatively constant value. Which means that you plug the device in take the reeding. Do the math Watts X Hours = Watthours X 1000 = KWH. And if you already know the wattage of a device you don’t need the Kill-A-Watt to figure out how much it will cost you to run that device for a month. Example 100 Watt light bulb
you burn it an average of 5 hours per day. 100X5=500X30days=
15000/1000=15 KWH X $0.0917= $1.3755 or $1.38
Where the KWH counter comes in handy on the Kill-A-Watt is for things like a Refrigerator, Coffee maker, Crockpot, Electric blanket, Water-bed Heater, things that have a thermostat and randomly cycle on and off. But for an accurate reading you need to leave it plugged in for at least a weak. Power to run the
Kill-A-Watt on a 4400 is 0.947 Watts. And to answer the other question. About things being plugged and turned off. If it has a remote control yes it takes power. In most cases less than 2 Watts the secret killers is the Cable or Satellite DVR’s mine draws 37Watts 24/7 when off 43 when on and it’s not a HD model. I have herd that some are lot worse than that. Also anything with a clock in it like your Coffee maker Microwave etc. Also Computers unless you turn off the little black rocker switch on the power supply on the back of the computer it draws power, only 3-4 watts, but when you add it all up. There is between 40-90Watts draw when no one is home and that don’t count the Refrigerator.

By: Diana

Diana — Mon, 29 Nov 2010 20:51:41 +0000

Are we pulling power when an electric object is plugged in but the switch is not on the ON position?

By: PERRYinLA

PERRYinLA — Mon, 25 Oct 2010 18:51:12 +0000

For those of you on the west coast, this device (the P4400 model) is now for sale at Fry’s for $14.99.

By: TNK

TNK — Wed, 11 Aug 2010 19:12:32 +0000

Great news.. our local library in conjunction with Xcel Energy have 40 Energy meters available for use for free. 2 week check out period. If Xcel Energy is your provider, you may want to check with them directly or with your local library to see if they have these available (their versions hook into your computer too!!!).

By: cristina

cristina — Tue, 03 Aug 2010 16:38:39 +0000

I think the Ted 5000 is a great thing to own as well. You can connect it to Google PowerMeter to track it on a daily basis.

I have even connected it to a game for my kids to teach them how to be more energy efficient.

ttp://nexus.kumagames.com/portal/welcome/t5000

By: Josh

Josh — Wed, 05 May 2010 20:17:40 +0000

I would suggest this to undercomplicate the entire process. Use this guy on your big electricity consumers like lightbulbs, appliances, and then the smaller ones if you are really trying to cut costs. Write a quick chart of how much each one costs to run for an hour. Pick the ones that look particularly nasty and go buy some garage sale stickers (the ones with different color dots). Red for big consumer, Orange for medium, and Yellow for small. YOU decide which is which. Then you can use the thing just to try out different combinations later.

By: Peter B

Peter B — Fri, 30 Apr 2010 00:42:44 +0000

NIST Team Demystifies Utility of Power Factor Correction Devices
http://www.nist.gov/eeel/quantum/power_121509.cfm

By: Gordon James

Gordon James — Sat, 06 Mar 2010 01:47:57 +0000

I just bought an item on ebay listed as
18KW Power Saver

it claims to “use a state of the art electrical technology to actively monitor and improve the power factor of electrical appliances ,suit for household or office.”

so, it claims to improve “power factor” (PF=W/Vrms Arms)

This will make the most difference in . .
Electric motors
Fluorescent bulbs
(probably) bad connections in heating device thermostats

A brief explanation of how it works is here.

Anyone have comments or experience with this?

By: Ed

Ed — Thu, 18 Feb 2010 01:24:01 +0000

@Mark – I think the culprit is the neighbor…

By: Mark

Mark — Tue, 26 Jan 2010 15:03:59 +0000

Ahhhhhhhhh!!! HELP? My electric usage went up 2 – 3 times more than last year. I’ve done what the electric company said to do and determined during my investigation that my 20 + year old refridge needed to be replaced and that my hot water heater had passed it prime 6 years earlier. Upon replacing them, my usage and bill went down, but my usage is still at least double than the years before. We keep our home at 65 during the winter and still we’re getting gouged. What culprit/s should we look at more closely?

Thanks, Gouge-o Marks

By: The Gadgeteer’s Top 25 Reviews of 2009 — The Gadgeteer

The Gadgeteer’s Top 25 Reviews of 2009 — The Gadgeteer — Tue, 05 Jan 2010 11:41:15 +0000

[...] Kill-A-Watt Electric Usage Monitor by Judie Lipsett (December, [...]

By: Killawattfan

Killawattfan — Sun, 13 Dec 2009 21:41:35 +0000

Fredrick,
I don’t know how long you have had your kaw, but mine ended up having broke the pins from the internal circuit board after about 5 years of ownership hard use. I had used a short 1 foot long right angle with swivel jumper cord for better access to outlets behind fridges and furniture. I don’t know if the cord broke them, or if it was just wear and tear. I’m ordering 3 more units, but a mix of the 4400 and 4480 ( the newest unit) with graphic display. The 4400 has been fantastic, I found a problem in my friends business that was burning out their refrig. units due to over voltage. When the power company guy showed up,
he pooh-poohed my unit-said he would hook his up and get a true reading of voltage–mine was .1 number different- he was impressed then. His meter was $400.00. Mine 22.00 at radio shack closeout years ago. I would not use this unit for a long term (anything over where I was not watching it) for a heating type appliance. Sorry this was so long.

By: Fredrick

Fredrick — Fri, 11 Dec 2009 08:39:17 +0000

My Kill A Watt was killed last night. Was using it to measure the KWh of my resistive heater and this morning a horrible plastic smell in the room. There were burn marks on the front plug pins. I had the heater on the 1500W setting and the KAW says max 1875.

I suppose it could have been the plug from the heater, it’s also burned black on the contacts.

By: MG

MG — Thu, 10 Dec 2009 17:38:16 +0000

We used two Kill-a-Watts to compare Christmas Lights.

http://www.grimaldielectric.com/services/green-tips/97-holiday-and-christmas-lighting-led-holiday-lights-versus-traditional-holiday-lights.html

By: Bill

Bill — Tue, 08 Dec 2009 21:10:41 +0000

Incidently, this is while running.

By: Bill Land

Bill Land — Tue, 08 Dec 2009 21:08:46 +0000

I have no idea if my frig., 10 years old is worth replacing? It shows .19 on Kwh and 174 watts with 2.4 amps and 120.4 volts. Can you help?

By: Don

Don — Sun, 15 Nov 2009 15:13:49 +0000

I’ve had a KAW for about 2 weeks. I first used it to measure a 35 year old chest freezer that I found was using over 1600 kWh a year! I replaced it last week and after 2 days the new one has used .20 kWh (35 kWh per year). If you assume a cost of $.09 which seems common then I will save 1565 x $.09 = $140 per year and I get the cost of my $600 freezer back in 4 years. My new freezer is rated at 357 kWh per year which is 10 times what I measured with my KAW but it seems to only draw about 80 watts when running and won’t run often if kept full and closed. Even if I use the entire 357 kWh as per the rating, I save about $112 a year for a payback period of less than 6 years.

I also measured my 5 year old desktop computer which draws about 190 watts. It drops to about 10 watts when powered down and only to 0 if unplugged. I have an Asus netbook that draws about 13 watts when plugged and running on AC. Now I tend to shut off my desktop most of the time except when I want to do some more serious surfing, email, or when updating files I want to keep secure (I have USB backup drives for the desktop. I use the netbook to check email or stock markets throughout the day, saving about 160 watts per hour. It also shows the value of shutting off the PC when not in use. When mine goes into “standby” it still sucks up 145 watts (the saving is mostly the LCD monitor in save mode).

By: Guillaume

Guillaume — Thu, 05 Nov 2009 18:40:56 +0000

HM/Stehen

Love hearing two smart people talking. So much bullshit around these days.

It sound like a useful device that is pretty accurate, and for $25, I’d buy a couple. I’m an EE and and an ex-physics grad, so I do understand all of the basics, but its a PITA that folks who build the appartments where I live (Hong Kong), and most of the appartments in Asia pay no attention whatsoever to energy conservation.

Out here, the main problem is heat. If its 30C all year round, then the main cost of life after paying the rent (building) and food is the cooling, ..the aircon!I have a batchelor falt that is little more than 200 square feet, but all the aircon can do is keep it dry and one or two degrees less than the outside air temperature. That means an appartment ambient of more than 27C for 6 months of the year with the aircon full on.

Compare that to a house I have in Europe that was 2,500 square feet? Bizarre thing was that was cheaper $ for $. Cheaper to cool 2,0500 square feet than 200 degC by degC. So the Hong Kong style buildings where it is just pure concrete with zero insulation, are costing me $100 a month instead of $10 per month.

When I complain to my landlord, he can use a weak excuses: “You leave the lights on to much(Yes, but all are fluorescent)”, “You cook a lot at home (true, but microwave covers half of it, and there the consumption is almost nil if you average it out over a year). I can just here the idiots saying “you don’t realise how much your TV costs “(zero, I don’t have a TV), “and the cooking” (2KW at say 1 hour per day, I can calculate that pretty easiily).

If I look at the real answers, I can estimate, roughly (+- 5%), that cooking is about 10%. Aircon is about 85%. The rest is the bits and pieces, mostly PC related. Lighting is irrelevant when flourescent tubes or bulbs are used.

At least when the idiots say “you consume to much, you should be careful”, then I can wave the $25 box in the air and say “That’s wrong, I have the proof on spreadsheet, next question?”

Commons sense and a bit of learning helps a lot. But, in the end, a black box can talk harder!

By: Hm

Hm — Wed, 15 Jul 2009 21:09:11 +0000

Stephen —

That’s not obtuse at all, it’s smart. While it doesn’t give you a number, it costs $0, no s/h, no packaging, no manual and no fishing it out of the closet. It’s also a good way to determine whether to bother unplugging wall-warts etc.
I recall a quick-thinking tech who used that method to check if a router was bad. The wall-wart was cold, which led us to isolate the problem in another 30 seconds.