Paul.... where did you by your Kill a watt and does it
work well?
Do you consider it a must have "tool"?
If you checked the Amazon link, there is a Kill-a-Watt there
that is pretty cheap.
The gadget I have, is a clamp-on AC/DC ammeter. I use it inside the
PC, and also for other odds and ends. For example, last year,
the starter on my car started to act up, and I was checking the
current draw on that. When it got cold, the starter motor was
drawing 150 amps. Eventually, it stopped turning over in cold
weather.
Since the clamp-on ammeter is a non-contact meter, I can work on
stuff like that, without any current flowing through the
instrument - it senses the magnetic field around the wire.
I've also used it on my central air conditioner, that runs
on 220VAC. The fan that blows the air, is drawing twice the
rated current, and I have to lubricate the motor much more
frequently, to keep it running quietly. (I wasn't able to
find the right replacement for it, as the proper replacement
is no longer made. So I live with it.)
In the picture here, the jaws open on the end, and go around
the wire to measure. It has a Hall probe inside, and that is
how it can measure an AC or DC magnetic field, and figure out
the current flow.
http://exphil.com/images/products/Extech/380947.jpg
The Kill-a-Watt meter, is for saving money on A.C. electricity.
If you want to know how much power your gear uses, that is
the meter to use. If you have a wasteful appliance, or a wall
wart that wastes power, it is simple to check them. But that is
its only function, so it is a specialized gadget. Whatever you
measure, has to have an AC power cord on it, to plug into
the meter.
The clamp-on ammeter can work on a bit more stuff. For example,
if you were running a PC repair business, in about a minute,
you'd be able to precisely tell a customer whether their power
supply was big enough or not, using the clamp-on ammeter to measure
all the DC rails in the PC. The only constraint, is the need to
put the jaws around the wire to be measured. (I made an AC
line cord, where the white, black, and green safety wires
are separated, and that is how I measure AC appliance currents.
But I cannot measure the power factor, while the Kill-a-Watt
can, if you get the right one. The power factor is the phase
angle between voltage and current, and sometimes you need to
know that when buying a UPS or uninterruptible power supply.)
Paul