Advice on electricity useage monitors

First off, does the electricity company's meter multiply the voltage by the current to calculate the power, regardless of the phase?
I'm looking at whether to buy a wireless electricity monitor such as this:
<(Amazon.com product link shortened) />/ B000LQ79Q6/ref=sr_1_1?ie=UTF8&s=electronics&qid02911664&sr=1-1>
which clips around the input meter lead so measuring the current and multiplies this by a set voltage to calculte the power consumption.
Or to buy a power monitor that actually measure the power used by the device:
<(Amazon.com product link shortened) />/ B000Q7PJGW/ref=pd_bxgy_ce_img_b?ie=UTF8&qid02911664&sr=1-1>
Thanks
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wrote:

Since this is a DIY group:
http://offog.org/code/electricity.html
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The point that the LED flash rate on the utility meter is proportional to the rate of electricity consumption is very useful to know.

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Get the proper power meter one.
My Efergy whole house meter reads 76W for my PC/monitor/ADSL modem when in standby. A proper power factor corrected meter and what I am paying for reads only 15W.

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After a bit of research, it looks as if the utility companies in the UK simply multiply the instantaneous voltage and current and average this over time to get the apparent power. This is what you pay for, rather than the real power you use which is the product of the in phase current and voltage. An ideal inductor as a load doesn't dissipate energy but the utility company still gets you to pay for the apparent power.
It looks as if the power meter is the best bet as long as it can measure the apparent power which I pay for rather than the actual power. Alternatively I can count the number of LED flashes on the utility meter with a fast finger on my stopwatch :)

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Correct.
No, it's integrated over time to give you the actual energy usage.

No it doesn't.
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