Review: 2000MU-UK vs PM230
(AKA "power monitors" or "energy monitors".)
When I first started getting the energy-efficiency bug seriously (in mid-2007) I looked for an equivalent of the famous "Kill-a-Watt" meter well-known in the US.
At the time the quickest and easiest and cheapest for me to buy (on-line) was the PM230 kWh meter from EnergyOptimizersDirect. And it works well and helped in identifing what we'd need to work on first to trim our electricity consumption, especially my office computer network and our domestic fridge/freezer. Both have now been replaced to good effect.
Just being able to plug an appliance in, and plug this unit back into the original socket is very easy, and the unit is robust and easy to read. I've never bothered putting in a battery to retain readings and set-up.
A weakness of the PM230 is that is seems not to be able to measure below ~7W, which limits its ability to monitor already-efficient appliances.
The PM230 is also a little fiddly in requiring you to page it through various modes, requiring several pushes to get to the 'W' reading that I use most, which can be tricky when the meter/socket is difficult to access.
Possibly even more annoying is that given the layout of the PM230 the appliance lead from the plug partially obscures the display and can make the central button difficult or impossible to use.
As of 2008/03 I was sent a 2000MU-UK meter stocked by Maplin for as little as £10 during special offers. (I was sent mine by someone who had two!)
Three things struck me immediately on using the 2000MU-UK:
- It was a little quicker and easier to use with a single button push for the Watts readout.
- It can report much lower power readings, apparently reliably, down to 1W.
- It tends to give lower readings for many appliances, possibly because it can measure lower-power items more accurately, and partially because it may be correcting better for power-factor (the difference between VA and W), which is important for electronic gadgets.
Although the 2000MU-UK seemed robust enough to me, I had reports that it can be fragile in some circumstances, so I'd advise against heavy-handed jamming-in of plugs, etc.
I don't have a test rig to measure these two meters' accuracy against, and the fact that the 2000MU reads consistently lower than the PM230 does not indicate which is the more accurate though the 2000MU seems more precise (ie able to measure smaller values), but I'm inclined to believe the 2000MU values since they accord with other independent measurements that I've been able to make.
The 2000MU-UK is as robust and easy to read as the PM230, so given its sometime lower price and easy availability from Maplin, and its possibly better accuracy and precision, I recommend the 2000MU-UK.
The 2000MU-UK and PM230 side-by-side (the 2000MU is on the left).