Owl Cm119 Wireless Electricity Monitor

It has had exactly the effect that it promised: at a glance we can tell whether we have left lights, computers, or even a cooker ring on somewhere unnecessarily, and we go and turn them off. It is cutting our electricity use by at least 25%.What gets measured gets managed. And my husband is addicted: he has even been known to produce it when we have guests, no doubt boring them to death with his chatter about how much electricity we used to use!

I agree with everything Paul Ell (above) has written. Like Mr. Ell, I found that the two main cables (apart from the green/yellow earth) from my electricity meter were grey; according to the instruction leaflet one should be red, and the sensor attached to that. I attached the sensor to the right-hand cable, and it was correct. Incidentally it is a very tight fit, a snap-shut fitting which only just fitted the cable; I assume the designers intend this.

In general, I think the booklet could be improved upon; it is in very small print and did not seem particularly easy to understand at first reading, although there is also a fold-out 'idiot's guide' included with the box. Also you MUST have a really small cross-headed screwdriver to hand (like a jeweller's) to get access to the battery compartments on both sender and receiver units. (Batteries are included thankfully).

Having said all this, once up and running, I have found it invaluable. You can set the display for Cost, Energy (kW) or Greenhouse Gasses. There is a problem with the Cost function, as if like me you are on a tariff which decreases once past a certain kWh useage, the Owl cannot be set to automatically adjust, although it can be set to adjust to different tariffs at different times of day. So I have mainly used - as I suspect most people will - the Energy display. This shows how much energy is being consumed at any one time and is a real eye opener. I found that a 3 bar electric fire which had all the bars turned off was still using approximately 700 Watts! This turned out to be a convection heater which is built in and which I had, until now, assumed to consume negligible current. Also, like another reviewer, I found that despite turning off/ unplugging everything in the house, there was still over 100 Watt consumption taking place. Is that the meter itself.....?!

Seriously, it really is worth every penny, and I am sure will rapidly repay its cost given today's energy prices.

Recommended strongly.

This meter is great for giving you an overview of your current household usage. It's nice that you can keep the display somewhere central (like the kitchen) and take a look now and then.

However, I kind of got the wrong impression from John Nance's review (21 Jun 2007). This meter isn't really suitable for measuring individual appliances. It's not sensitive enough to accurately measure many things. 60W devices register, but not accurately (e.g. switch one 60W light bulb on - the reading goes up by 30W; switch a second identical 60W light bulb on - the reading goes up by another 80W). Low power devices such as TVs, Hi-Fi's and radios don't register at all. If it's small appliances like these you're interested in measuring, consider one of the plug-in meters.