####What is it?
The MS6115 mains power meter is a device for measuring the electrical power used by an appliance. It looks like an electronic timer switch (see photo at right). You plug it into your power point, and then plug your appliance into it to measure its power use.
####What does it do?
You can use the MS6115 to measure voltage, frequency, current, power and power factor, as well as the maximum power drawn while using an appliance. These can be interesting measurements, but the real value lies in its ability to report cumulative power drawn in kWh.
####What can I use it for?
Earlier in the week I wrote an article on some of the [things you can do with a mains power meter](http://green-change.com/2008/11/25/using-a-plugin-power-meter/).
In summary, you can use it to:
– measure peak power/current drawn by an appliance
– measure daily power usage or operating cost of an appliance
– measure per-run power usage of an appliance (good for dishwashers, washing machines, etc)
– compare power usage for different operating modes of an appliance
– compare power usage of different appliances that have the same use
– check for phantom power drawn by appliances in standby mode
If you have an electricity plan with variable tariffs at different times of the day, the MS6115 can be programmed with those details so you can work out exactly how much money an appliance costs to run. You can then make decisions about the preferred time of day to run it.
####How well does it work?
In general, the MS6115 works very well. The instructions are a little unclear, but its basic operation is very simple. You just press the Func button to switch between different measurement displays, and press-and-hold the Func button to reset the cumulative totals (kWh and cost). Programming in the variable tariffs gets a little more fiddly, but isn’t too hard.
I have read in other reviews (see below) that this power meter isn’t super accurate. It’s plenty good enough for measuring household power consumption and comparing figures between different appliances or usage patterns, though. You don’t need perfect accuracy for that – if you’re within 10% you’re still getting a good picture of your energy use.
Accuracy is apparently pretty bad at lower current levels, which may limit its usefulness in investigating phantom power of standby appliances. Still, you can get a decent idea of which appliances are drawing power constantly, and by leaving it running for a longer period of time your cumulative total will become more accurate.
The cumulative power use (kWh) reading only displays to 1 decimal place. For appliances that don’t really use a lot of power, you may have to run them for longer or measure power consumption over multiple uses of the appliance to get a more accurate measure.
The MS6115 is apparently quite inaccurate for measuring power use by loads with high-frequency harmonics such as switched-mode computer power supplies. Its inaccuracy will be fairly linear, though, so you can still use it to compare power usage of the same computer in normal use, energy-save mode and hibernate mode, for example.
####What does it cost?
Most retailers seem to be selling the MS6115 for $30-$40, although I have seen it advertised higher.
####Where can I get it?
– [Jaycar](http://www.jaycar.com.au/productView.asp?ID=ms6115) – they have a store in Wollongong, but you can search for other [store locations](http://www.jaycar.com.au/stores.asp). They also seem to sell some products through Magnet Mart at Albion Park Rail.
– [Todae](http://www.todae.com.au/Products/officeenergysaving/multifunctionpowerenergymeter/) – they are a bit expensive compared to other suppliers, but will deliver.
– [eBay](http://www.ebay.com.au) – search for “MS6115”, although they didn’t seem any cheaper than Jaycar when I looked.
####Can I see the manual?
Sure, why not. Be warned that it’s not very clear, though!
####Where can I find other reviews?
– [Choice review](http://www.choice.com.au/viewArticle.aspx?id=106100&catId=100285&tid=100008) – decent technical analysis against a calibrated meter. They say the power factor measurement isn’t very accurate, and the power measurement is inaccurate at low levels (e.g. measuring standby power draw).
– [Low Impact review](http://www.low-impact.net/index.php/20071202/the-ms6115-power-meter/) – a good review by a happy user.
– [Rowetel review](http://www.rowetel.com/blog/?p=42) – a good practical example of using this meter to reduce household energy consumption.
– [DansData](http://www.dansdata.com/quickshot041.htm) – another good practical example.
– [Solarhome.com.au](http://www.solarhome.com.au/?p=118) – has some easy-to-read instructions (better than the manual!).