Re: Kill-a-Watt meter for 110-220 Volts

[Martin Brown]

I'm in California, USA. During the summer, the wall mounted air
conditioner probably consumes around 80 to 90 percent of the electric
power used in my apartment.

This AC unit has a 220 power plug that's plugged into an outlet right next
to it.

Is there a Kill-a-Watt meter that does both 110 and 220 volts AC? I've
heard of a higher than 110 volts model obtainable in Europe, but I would
need one that works with the USA version of plug style, voltage, and AC
frequency.

I would hazard a guess that the inline European ones designed for 240v
would also work on a 110v supply without too much trouble (probably less
accurately and maybe needing empirical calibration).

But the other way around the US ones will be made down to a cheap and
nasty price and probably cannot safely be used at 240v. The same seems
to be true of many US wallwarts which are dedicated to 110v whereas in
almost all other countries they are commonly for 100-240v 50-60Hz.

The clip on magnetically coupled devices like OWL are probably your best
bet if the cabling will allow the sensor to be fitted. Accuracy +/-10W
is poor compared to inline ones but for A/C should not matter.

http://www.amazon.co.uk/Owl-Cm119-Wireless-Electricity-Monitor/dp/B001JJCLS0/ref=dp_cp_ob_ce_title_0

I presume smart meters are also available in the USA, but a quick web
search didn't show anything obvious.

It is probably more informative to use this type to monitor the entire
apartments usage - you can deduce the aircons consumption from how much
the thing jumps by when the compressor kicks in. You might need a pair
of magnetic sensors since ISTR US 240 is across antiphase 110v supply.

Regards,
Martin Brown

 

[[email protected]]

I would hazard a guess that the inline European ones designed for 240v
would also work on a 110v supply without too much trouble (probably less
accurately and maybe needing empirical calibration).

But the other way around the US ones will be made down to a cheap and
nasty price and probably cannot safely be used at 240v. The same seems
to be true of many US wallwarts which are dedicated to 110v whereas in
almost all other countries they are commonly for 100-240v 50-60Hz.

Kill-A-Watts monitor the neutral current (keeps the innards at a low voltage),
so are useless, as is, for standard US 240V split-phase. A friend hacked one
to monitor the hot current and it worked just fine on a 240V circuit. Safe?
Well, it was hacked. ;-)

 

[Hammy]

Kill-A-Watts monitor the neutral current (keeps the innards at a low
voltage), so are useless, as is, for standard US 240V split-phase. A
friend hacked one to monitor the hot current and it worked just fine
on a 240V circuit. Safe? Well, it was hacked. ;-)

I just used mine on a 300W boost PFC and according to the kill a watt my
boost converter is makeing power. For a measured 130W out the Kill a watt
says my boost is only drawing 115W @ 0.97 PF.

I have seen it get closer on other SMPS's but its off here!

 

[Eeyore]

I just used mine on a 300W boost PFC and according to the kill a watt my
boost converter is makeing power. For a measured 130W out the Kill a watt
says my boost is only drawing 115W @ 0.97 PF.

I have seen it get closer on other SMPS's but its off here!

There are some really cheap and nasty meters of this type that are
hopelessly inaccurate. I suspect you have one.

Graham