Smart meter accuracy

Gerry1

darrude said:

*1.74 amp average per hour over 24 hours:

Nope.  1.74 amp average over 24 hours:

darrude

[Deleted User] said:

darrude said:

I've done my first true 24 hour (exactly) reading test.

Electric Meter: 18.6KWH
Clamp on Meter: 10.0KWH*

*1.74 amp average per hour over 24 hours:

 so 1.74 * 24 * Volts =

230 volts: 9.6 KWH
240 Volts: 10 KWH
250 Volts: 10.4 KWH

I am not sure what you are hoping to prove with all this testing? No supplier is going to accept calculations from third-party metering devices. If you genuinely believe that your present meter is faulty then ask the supplier to fit a test meter. If the test meter finds in your favour then your usage will be adjusted. If the present meter is shown to be accurate, then you will be charged for the test meter.

Good point, I have asked them to do that, but they don't seem too forthcoming, so hoping to justify it a bit to them.  I think this is just to justify it myself really.

Grizzlebeard

darrude said:

I've done my first true 24 hour (exactly) reading test.

Electric Meter: 18.6KWH
Clamp on Meter: 10.0KWH*

... snip ....

Sorry darrude, the Clamp on Meter is not going to give reliable True RMS (Root Mean Square) readings (Like the utilities Electric Meter) for  the reasons I posted earlier. It would meet its published spec for an electric heater or old fashioned tungsten light bulb. Anything that has a complex load - washing machine, led light bulb, computer, TV, Fridge, Freezer, EV charger, etc. etc. and the best it can do is make a crude estimate.

Look up "True RMS Meter" on the internet and you won't find anything under a few hundred £. It's the domain of professional Lab style equipment. And most of those will only measure Amps and/or Volts and don't have the ability to calculate the True RMS Watts but only the VA, which as gerry1 said is different.

My equipment to measure True RMS Watts output from the amplifiers I used to design cost over £2000 (today around £1500 and more sophisticated) and even then I had to do sums on a calculator to establish the real RMS performance when the amplifiers were feeding real-world loudspeakers.

The circuitry inside the Utilities Electric Meter is considerably more sophisticated than anything we can buy in a small plastic box on the internet.

Having said that it doesn't mean your Electric meter doesn't have a fault.

The most reliable way to self-measure that would be to turn off absolutely EVERYTHING in the house (Throw all the breakers but one) then either fire up a 3kW electric kettle or plug in a 1-2kW electric fire for an hour and read the flashes on the meter. Even then, don't expect a 1kW fire to be exactly 1kW. It's probably closer to 950W but could be, say, 1.1kW. A "3kW" kettle typically draws 2.8kW to keep it well under the 13A plug limit.

With this experiment your Clamp on Meter would probably give readings pretty close the the Electric Meter.

Tallerdave

Penelopa.Pitstop said:

I bought this in 2017 and it's pretty accurate. It's not on sale any more, but maybe there's updated model.
https://www.amazon.co.uk/gp/product/B00JIMQP6Y You can compare spec and functionality of yours and see if there's any difference in a way they measure usage.

Unless you heat your water a lot, I would say, that you use a lot of gas in summer.

They're excellent and occasionally pop up on ebay. However, the CT clip version seems to be rarer than the meter led version.