I’ve been seeing a lot of this electricity measuring gadget on the Internet and decided to buy it to see how it really works. in essence, it’s a great tool for do-it-yourselfers or anyone who just wants to find out how much electricity usage each device in their home uses up.  It’s a great gadget but with a caveat i’ll mention a bit later…

Kill-A-Watt in action

Kill-A-Watt in action

Why this device?

Anyone who wants to save on electricity should really know how much electricity they use in the first place. Of course, you can always take a peek at your electricity meter from the power company and compute the total number of kilowatts hours  (that’s another way of saying 1 thousand watts in an hour) you’ve used up… but which appliances are those that really use up the bulk of that electricity?

In comes the Kill-A-Watt device.. it’s really a measuring device that measures voltage (i.e. 110 volts or 220 volts) and current (Amps) and power (Watts).  Since most houses come with 110 volts, what’s really important is to figure out the number of watts each item in your house uses.   The bigger the number of watts it uses, the more power and the larger your monthly bill would be if it was used all the time.

How to use it?

To use the Kill-A-Watt, all you have to do is plug it in your outlet and then plug in your appliance/item into the kill-a-watt socket.  Once that’s done, turn on your appliance and press the “Watt” button.  It’s going to show you the total # of watts your appliance is using at any given time.  Pretty easy!

Some examples:

1. This computer I am using to write this is has an AMD Athlon 64 processor with 2 Gb and a hard drive & DVD drive… with normal usage, I get about 45 watts.  If I am running a video or doing some CPU-intensive things, then it goes up to about 65 or 70 watts.  The 19″ LCD monitor attached to it uses about 16 watts of power… so a total of about 60-70 watts.

2. I also have a Toshiba Laptop (older model) that uses up about 40 watts normally. If the LCD display is off, then it goes down to 35 watts.  If it’s fully charged, then it goes even lower.. only using up about 17 watts in normal usage… pretty neat.

3. Canon Laser Printer. For this, I have it on standby most of the time and it uses up about 2-3 watts… pretty good because some devices use up a lot more power on standby than you think!

You can go all around your house and do the same thing until you get a list of which appliances use up the most power.  This gives you a great idea on how to save on electricity costs by just changing the way you do things everyday.

For example, I used to leave my PC on the whole day and night since I don’t like having to wait for my computer to boot up when I want to use it… seeing how it uses up power though.. it makes sense to just turn it off especially at night.  (60 watts of power x 24 hours X 30 days = 43,200 watts or 48 killowatt/hours). At about 10 cents per KWH, then that’s already $4.80.. most of it wasted power since the PC is not being used most of the time.

Another example… if you have a widescreen LCD TV that uses up, say 700watts… using it for 4 hours a day uses up 84 kwh (700 w x 4 hrs * 30 days = 84,000 watt-hours).. or $8.40 addition to your bill.  If you don’t turn it off for the whole day (i.e. 12 hours on), then it comes out to about  252kwh or $25.20!  Makes sense to turn that off when you’re not watching TV…

I guess the good thing about gadgets like these is that it gives us a concrete idea of how much electricity a device uses.  Without it, we don’t really know which ones use the most power and we can’t really make a plan to save if we don’t know what to save on.

‘The Caveat(s)’

I guess it’s time for the caveat/warning… the main thing I didn’t appreciate with this device is that it’s a bit bulky and doesn’t do well if plugged into the wall socket since it really has to be on the top socket to be readable. It’s especially hard if you have to plug it into a thin extension cord.. you basically lose about 3 - 4 outlets since this thing covers almost everything.  I wish it was either thinner or it had a kind of built-in extension cable so this would be less of a problem! (See my picture above to see how it looks in a normal wall socket).

There’s also another warning that needs to be said… since this is a plug-in device.. you can’t really use this to figure out usage for some household things like, say, your furnace or pumps or other “built-in” devices.  In some cases, it’s also a bit hard to reach into the back of your large fridge (or other large appliances) just to plug it into the wall socket - especially if you have recessed or customized fitting panels all around the appliance. (i.e. stoves, diswashers, etc).

A way to remedy this is maybe think of other devices like an Ammeter (measures current) that comes with a loop.  This kind of device is more for the professional and is more expensive but it allows you to measure current without needing to unplug the appliance.. just slip in the loop on the wire and you get a reading right away. :)

Another way, is simply to calculate estimated wattage by using the Power formula:

Power (Watts) = Voltage (Volts) x Current (Amps)

… but that’s best kept for another article… see you then and happy measuring! …