Electricity usage with nothing plugged in.

JackSnap

Yes its not a big draw, but its a draw, and i still cant figure it out, its not the cost thats bothering me, just the principle really.

Ive been all around the house, including the attik , theres nothing in there, no sign of electric wires even.
I have no alarm, and theres really nothing else i can think of.(boiler and cooker are hard wired but ive turned them off.) actually whilst writing this two things have sprung to mind.
one is the front door bell, it has no batteries in, but its still working, so must be wired, and then theres the central heating clock. the digital display is on even if i turn off the power to the boiler, in fact the display stays on even if i switch off the fuse box so must have a battery back up too.
I cant believe these are taking 30W between them, but then i have no accurate way to measure that small amount.

only way is to do as was suggested and monitor the meter with only this small draw, but it goes so slowly that i would have to leave it going for a few days to get a reading, which isnt practical because of my food in the fridge etc.

getting closer though, and its amazing how the cost would build up, being on economy 7 im charged 22P a unit at top rate now, over a year thats significant to me.

Incisor

moonrakerz wrote: »

The "bog standard" domestic electricity meter does not correct for power factor !
Some of the very sophisticated modern devices can measure/record this but it is not corrected for in the meter.

The spinning wheel type of meter measures current flow only, this is corrected mechanically to give a read out value in kWh (usually). The usual figure of power factor applied in the mechanics of the meter is around 0.74, but this can vary depending on the type of meter.
If your power consumption is based on a totally different power factor this is (usually) achieved by application of an agreed pf figure in the billing or a fixed figure being built into the meter just as in a domestic meter.

To return to the OP, a meter, like any electrically driven device, actually does consumes power to operate so it is possible that he is seeing the power used by the meter !

Sorry mate:
The metallic disc is acted upon by two coils. One coil is connected in such a way that it produces a magnetic flux in proportion to the voltage and the other produces a magnetic flux in proportion to the current. The field of the voltage coil is delayed by 90 degrees using a lag coil. This produces eddy currents in the disc and the effect is such that a force is exerted on the disc in proportion to the product of the instantaneous current and voltage. A permanent magnet exerts an opposing force proportional to the speed of rotation of the disc - this acts as a brake which causes the disc to stop spinning when power stops being drawn rather than allowing it to spin faster and faster. This causes the disc to rotate at a speed proportional to the power being used.
[http://en.wikipedia.org/wiki/Electricity_meter]

So, there you go, the meter integrates the product of the instantaneous current and voltage [if the power factor were zero, what do you think the integral of the instantaneous products of current and voltage would be?]. So there is no blanket 0.74 assumed power factor. And, contrary to what you write, it takes into account voltage as well as current. For clarity, this is the old spinning wheel meter I am talking about.

I know wikipedia is not always 100%, but if you think the wikipedia article is wrong on this, then please put it right. :rolleyes:

Incisor

JackSnap wrote: »

Yes its not a big draw, but its a draw, and i still cant figure it out, its not the cost thats bothering me, just the principle really.

Ive been all around the house, including the attik , theres nothing in there, no sign of electric wires even.
I have no alarm, and theres really nothing else i can think of.(boiler and cooker are hard wired but ive turned them off.) actually whilst writing this two things have sprung to mind.
one is the front door bell, it has no batteries in, but its still working, so must be wired, and then theres the central heating clock. the digital display is on even if i turn off the power to the boiler, in fact the display stays on even if i switch off the fuse box so must have a battery back up too.
I cant believe these are taking 30W between them, but then i have no accurate way to measure that small amount.

Wot BagOfSpanners says, believe your tariff meter. It is accurate.

only way is to do as was suggested and monitor the meter with only this small draw, but it goes so slowly that i would have to leave it going for a few days to get a reading, which isnt practical because of my food in the fridge etc.

There is another way.

• Go to your meter, and on it you will find the number of revs per kWh. eg: 166.67 revs/kWh. Post that figure here.
• Again at the meter, with everything turned off for some minutes, watch for the big black mark to come around on the disc and time 1 revolution in seconds [you may need to have a light running to get used to seeing the black mark]. Post the number of seconds here too.

Someone should then be able to calculate your chargeable consumption.

mech_2

1carminestocky wrote: »

By 'not a huge draw' I meant that the appliance/s which are causing the reading are not high consumption item/s. As regular readers will no doubt already know, maths is by no means my strongest subject but isn't 30 watts charged 24 hrs per day 365 days per year on my 10p per kw price just £26?

Yes. That's quite high if everything obvious is unplugged. About 8% of an average dual fuel household's consumption, and that's without a lot of the usual standby stuff plugged in. I think in a previous thread I was greeted with incredulity when I suggested standby consumption could amount to 10%. Well 8% is most of the way there already.

If so, you have refreshingly low leccy consumption..

Fairly typical of a one-person household without electrical heating.

Cardew

mech wrote: »

Yes. That's quite high if everything obvious is unplugged. About 8% of an average dual fuel household's consumption, and that's without a lot of the usual standby stuff plugged in. I think in a previous thread I was greeted with incredulity when I suggested standby consumption could amount to 10%. Well 8% is most of the way there already.

Mech,
I think that the point people are making is that the 30 watt reading on the eco-meter is probably a 'phantom' reading. It certainly doesn't appear to tally with the movement on the electricity meter.

My meter dial spins at 200 revs per kWh.

PrinceGaz

At 200 revs per kWh, the power being consumed by everything connected is equal to

Power (kW) = (3600 secs / 200 revs per kWh) / seconds per revolution

so
Power (kW) = 18 / seconds per revolution

or, as there 1,000 watts per kW
Power (watts) = 18,000 / seconds per revolution

therefore, if for example you found it completed one revolution in 35 mins 22 secs (= 2,122 secs)

Power (watts) = 18,000 / 2,122 = 8.48 watts

The same equation can be applied for any electric meter (by substituting the number of revolutions or flashes per kWh in the first equation and solving the "3,600 / x revs per kWh", to give the second or third equations).

Cardew

Agreed, and on my meter the 30 watts, that the OP's eco meter indicates, would mean one complete revolution every 10 minutes.

However the OP has not yet told us the Revs/kWh figure yet.

JackSnap

the meter says revs/KWH 200
as soon as i get chance to report the no of seconds i will, but its gonna be a lot, its moves REALLY slowly

PrinceGaz

JackSnap wrote: »

the meter says revs/KWH 200
as soon as i get chance to report the no of seconds i will, but its gonna be a lot, its moves REALLY slowly

It should move slowly if nothing is plugged in, in fact it shouldn't move at all. The good thing is that with a dial meter, you can see when it is approaching one revolution from quite some time before, whereas with a meter that has a flashing light (like mine), you have to remain vigilant for the entire period as at first you have no idea when it will flash (and when it does, you have to do it again to ensure you didn't blink or look away the first time).

If there is 30 watts being used by something in your premises, then at 200 revs per kWh, your electric meter should be running at exactly 10 minutes per revolution. In all likelihood, it will run much slower once everything is unplugged, down to the equivalent of less than 10 watts (there will still be some odds and ends connected that you can't see that use negligible amounts of power).