Electricity meter accuracy

[Gadgeroonie]

Any one on here a sparky who knows about meters ?

I suspect my meter is overreading

i have bought a clamp that goes over the wires from ebay and wanted to double check the meter is correct

i should be able to read the clamp and compare against the meter

how much electricity is each revolution of the dial ?

can i use a stopwatch to record say 10 revolutions and check the results against the clamp

thanks in advance

[davepoth]

There's no guarantee the clamp from ebay is accurate. I'd guess it'll be less accurate than the meter. Have you tried switching off everything in the house?

[Blue Oval84]

The meter should say on the front what one spin of the wheel equates to, I'm afraid I haven't seen a dial meter for a while at work, I believe that one spin equals 1/100th of a KWh. If you could post a picture I could confirm?

The publicly available clamp style devices are not very accurate so be careful about relying on it to confirm accuracy. By law, if you dispute the accuracy of your meter then your supplier must offer an accuracy test. They do however reserve the right to pass on some/all of the charges for this test if no fault is found.

Let us know how you get on!

[mattdaniels]

The toroidal clamp device will not be 100% accurate but it will be close, depending on how good a fit you can get around the wire. Bear in mind that these devices only measure current and assume voltage and power factor in their calculations.

What is making you suspect the meter is overreading?

[Simpo Two]

If it has a dial I'd day it's pretty old and possibly due for replacing anyway. See if your leccy board will fit a new one - they last about 10 years IIRC.

[Blue Oval84]

The board will only change the meter if it's due for re-certification, otherwise it's classed as a cosmetic meter exchange and chargeable.

The meter at my parent's house (built in 1998) has a serial beginning N59, this indicates the meter was manufactured in 1959 and it's still going strong! The dial meters are very reliable and just because it's old is no reason it should need changing.

[Dogwatch]

Blue Oval84 said:

The board will only change the meter if it's due for re-certification, otherwise it's classed as a cosmetic meter exchange and chargeable.

The meter at my parent's house (built in 1998) has a serial beginning N59, this indicates the meter was manufactured in 1959 and it's still going strong! The dial meters are very reliable and just because it's old is no reason it should need changing.

Mine is an 'L86' so must have been fitted shortly after we moved in (house is '56ish) though I don't remember them doing it.
Leccy co wrote and said it is due for replacement so are coming to do it on Thursday.

[Gadgeroonie]

cheers for the advice

if i were to turn off everything in the house except a 100 w bulb, how many revolutions should i expect in one minute ?

[Paul Drawmer]

It will tell you on the front of the meter what 1 revolution is. You will need to know that to work out how fast a 100W bulb will spin it. BTW, how accurate is your 100W bulb?

[Gadgeroonie]

"how accurate is your 100W bulb?"

thats exactly what i was thinking !

was going to see what the clamp thought of a 100 w bulb and take it from there !

[Deva Link]

Ours says 187.5 revs/KWH. So 100Watts, assuming unity power factor, would be 18.75 divided by 60 = 0.3125 of a turn.

[mattdaniels]

You'd be surprised how difficult it actually is turn absolutely everything off in the house apart from one bulb. It's easy enough to go around switching off sockets, and sure you can live with the fridge and freezer being off for an hour whilst you experiment. But don't forget about things like the cooker that has a digital clock on it, your central heating controller/timer and so on. And when you're convinced everything is off in the house, don't forget about your garage with the cordless power tools on charge or the car hooked up to the battery conditioner etc.

If you do want to get an electricity monitoring device to run a comparison against your metre, I sell the market leading device in the UK along with some monitoring software (the device connects to the PC via serial port). You can track your energy usage over a period of time and see how it compares to your bill.

[shimmey69]

mattdaniels said:

You'd be surprised how difficult it actually is turn absolutely everything off in the house apart from one bulb. It's easy enough to go around switching off sockets, and sure you can live with the fridge and freezer being off for an hour whilst you experiment. But don't forget about things like the cooker that has a digital clock on it, your central heating controller/timer and so on. And when you're convinced everything is off in the house, don't forget about your garage with the cordless power tools on charge or the car hooked up to the battery conditioner etc.

If you do want to get an electricity monitoring device to run a comparison against your metre, I sell the market leading device in the UK along with some monitoring software (the device connects to the PC via serial port). You can track your energy usage over a period of time and see how it compares to your bill.

Id be interested to know costs of this unit etc as sister in law bills have jumped from £60 to £500 a month for a 2 bed flat!

[eybic]

shimmey69 said:

Id be interested to know costs of this unit etc as sister in law bills have jumped from £60 to £500 a month for a 2 bed flat!

It's the ganja she's growing in the loft that's doing it

[Deva Link]

shimmey69 said:

Id be interested to know costs of this unit etc as sister in law bills have jumped from £60 to £500 a month for a 2 bed flat!

Look on his profile.

[Simpo Two]

shimmey69 said:

Id be interested to know costs of this unit etc as sister in law bills have jumped from £60 to £500 a month for a 2 bed flat!

When my mother's bills rocketed it turned out the timer on the Economy 7 meter was faulty and the storage heaters wre using some peak rate. Naturally the electricity company refused to believe me and threatened to take her to court for non-payment. Eventually I wrote them a rather robust letter and they changed the meter and apologised.

[Deva Link]

Simpo Two said:

shimmey69 said:

Id be interested to know costs of this unit etc as sister in law bills have jumped from £60 to £500 a month for a 2 bed flat!

When my mother's bills rocketed it turned out the timer on the Economy 7 meter was faulty and the storage heaters wre using some peak rate. Naturally the electricity company refused to believe me and threatened to take her to court for non-payment. Eventually I wrote them a rather robust letter and they changed the meter and apologised.

£500 in a month is beyond mental - I saw a very high bill in a place once where the immersion heater had been wired wrong so was on all the time, but even that was only a couple of hundred pounds over a quarter.

[mattdaniels]

shimmey69 said:

Id be interested to know costs of this unit etc as sister in law bills have jumped from £60 to £500 a month for a 2 bed flat!

Does she have her own meter in her own premisis or is there a shared area of meters? If the latter, has she checked for any signs of tampering eg. someone getting creative and hooking their supply off your SiL's meter?

[randlemarcus]

mattdaniels said:

If you do want to get an electricity monitoring device to run a comparison against your metre, I sell the market leading device in the UK along with some monitoring software (the device connects to the PC via serial port). You can track your energy usage over a period of time and see how it compares to your bill.

Serial port? Really?

Do you only sell the devices to people with access to computing museums?

[mattdaniels]

lol

It's a virtual serial port via USB.