Is my meter running fast?

[bellissimo]

Hi. I am just looking for some reassurance that I have a problem before I potentially fork out for someone to come round and check the meter.

I have been suspicious of our leccy bills for a while so decided to run a couple of tests. I have an energy monitor which I got from my provider (the kind which clamps to the mains cable), which seems to be reading a lot higher than the meter itself. Our meter is a digital one which flashes once for every watt used I believe. So I did the following:

1) I waited for a quiet period, and counted that the meter was flashing consistently at 20 times a minute. I then turned on the kettle. The kettle uses 2.8 kW, and the energy monitor measured an increase of 2.7kW. However the meter flashed 100 times a minute, an increase of 80. So 80 * 60 = 4800 = 4.8 kW!!

2) We have an MCB panel above the meter, so I turned the main switch off on this. I am presuming this means that we should definitely be using no power, but the meter still flashed 5 times a minute.

I would appreciate it if someone can confirm that these are valid tests, and that there is probably something wrong with the meter. (2) seems especially damning, but I am not sure if there would still be something else drawing power...

 

[PrenticeBoyofDerry]

I think it would be difficult to access the usage by the number of times the light flashed. A clamp meter would be a better method of measurement.

 

[bellissimo]

Are the flashes not a reliable unit of measurement then? Surely it should not flash if the power is totally off?

 

[foxhole]

Light does not reflect usage as you stated, you turned the power off to the house not to the meter so it would continue to flash too show it's working.

 

[bellissimo]

Hi. The meter says that it flashes once for every watt that passes through (or 1000 impressions per kWh). I would have thought that the only thing that could draw a watt through the meter is the MCB unit, which was turned off. (The meter itself presumably also draws a small current but I would have thought this was minimal). Maybe I am misunderstanding though.

 

[JohnW2]

Hi. The meter says that it flashes once for every watt that passes through (or 1000 impressions per kWh). I would have thought that the only thing that could draw a watt through the meter is the MCB unit, which was turned off. (The meter itself presumably also draws a small current but I would have thought this was minimal). Maybe I am misunderstanding though.

As you say, if you are using no electricity at all, the light should not flash. Are you sure that your consumer unit ('MCB unit') is the only thing connected to the meter? Do the pair of cables coming from the meter just going directly to the consumer unit, or do they connect to anything else on the way?

Kind Regards, John

 

[bellissimo]

Hi John. Yes, the consumer unit is in the same cupboard, directly above the meter. The two cables from the meter (black and red) go directly into the consumer unit as far as I can see.

 

[JohnW2]

Hi John. Yes, the consumer unit is in the same cupboard, directly above the meter. The two cables from the meter (black and red) go directly into the consumer unit as far as I can see.

Well, as I said, if the meter is connected to nothing other than the consumer unit and the meter is still flashing 5 times per minute when the CU's main switch is off, then something is definitely wrong. There aren't any other cables coming out of the meter that go anywhere else, are there?

Kind Regards, John

 

[bellissimo]

Nope, just those two cables going into the consumer unit.

 

[endecotp]

> I turned the main switch off on this. I am presuming this means
> that we should definitely be using no power, but the meter still
> flashed 5 times a minute.

Do the numbers still advance?

(I think those meters have a resolution of 0.01 kWh, so the least significant digit should advance after 10 flashes.)

Also in other threads, some have claimed that that LED flashes to indicate that the power is connected even when there is no load. That isn't how I recall that they worked, but there could be more than one sort of meter.

If you can actually see the numbers advancing when the switch is off, then I suggest that you take a video of it (just in case it fixes itself!) and report it to your supplier.

You might consider posting a photo so that we can look at where all the wires go.

 

[big-all]

to be honest i would go for more basic checks

as in compare your weekly/daily consumption with a period before you think its gone wrong then look at whats changed as in estimate to actual reading
increased unit costs or new electric toys or other changes that could account for the changes

 

[EFLImpudence]

We had a similar thread recently to which, I think, there was no conclusion or solution.
That one was flashing once every five seconds or twelve times a minute when there was said to be no usage,


To clarify:
If the meter is marked 1000 imp(ulse)s/kWh:

That means with a constant usage of 1W it will flash once an hour and proportionately quicker for more (constant) watts.

So, as this thread's meter is flashing once every twelve seconds that equates to 300W constant for however long you are seeing it.

Therefore if it were to flash at this rate when there was no usage, how would you know the difference.
I'm not saying that's wrong - I don't know - but it doesn't make much sense.
Were the usage to be less than 300W would it flash slower or is that the minimum?

 

[winston1]

I have an energy monitor which I got from my provider (the kind which clamps to the mains cable), which seems to be reading a lot higher than the meter itself.

They are mis described. They are not energy monitors they are current monitors. To monitor energy they need to be able to measure current, voltage and phase angle. Measuring current only they will often read high.

 

[endecotp]

I would expect a kettle to be near to a perfect resistive load, and for a clamp meter to give a reasonably accurate power measurement.

A kettle withna 13A plug could not reasonably draw 4.8 kW in any case...

 

[winston1]

I would expect a kettle to be near to a perfect resistive load, and for a clamp meter to give a reasonably accurate power measurement.

A kettle withna 13A plug could not reasonably draw 4.8 kW in any case...[/quote

It didn't. His/her energy monitor registered an increase of 2.7Kw assuming unity power factor is reasonable, the only error being assumed voltage versus actual voltage neither of which we know. Can't comment on meter flashes etc.