# electricity usage



## Delboy (11 Feb 2006)

Maybe somone out there can help me out on this one.

Myself and my gf live in a small 2 bed apt in Dublin. We were just looking at our last few ESB bills and cant figure out how we use the amount of units that we do....average 480 units on last 2 bills (240 units a month). Now I know this is'nt high by some standards and that in monetary terms it's only 80 euro per bill, but still we figure that this is way too high.

We have energy saving bulbs in all over the apt. We don't use the cooker every single day (its electricity powered). The TV on average (taking the w/e into account) is probably on 5-6 hours a day. Very few lights are on except in the rooms we're in. We do have an electric shower but that would'nt be on for more than 5 minutes a day (shower is brand new).We bought a PC at xmas but that gets very little use.We're both out and about during the day so the apt is empty, and all appliances are unplugged. The washing machine is on once every 2 days. So how do we manage to use 8 units of electricity a day!!!! 

A leaflet with our latest bill from the ESB says the following makes up 1 unit of power:
electric cooker - cooking for 1 person per day
lighting - 20 watt CFL = 50 hours
TV - 6-9 hours viewing

I reckon from lights, TV and the cooker that we use roughly 2 units a day. Surely the electric shower and the washing machine is'nt using the other 6 units!!!!!

Has anyone any info on this matter or experience of checking it out? Our last few bills are based on actual readings so it's not an estimate issue.


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## SineWave (11 Feb 2006)

Read your meter over an exact 24 hour period and calculate the units used. You're only talking about units used, as you have other standing charges and VAT lumped on the bill.

You might also like to read it over a weekend/holiday/xmas period and calculate the units used.

Let us know the figures.

From your bill, you are using an average of 8 units per day, which is 8Kw/hours per day (eg: a 100watt bulb running for 80 hours or 8 100watt bulbs running for 10 hrs or a 2Kw heater running for 4 hours or a 6Kw shower running for 70 minutes).

If the shower was run 4 times a day for 15 minutes, you would have almost come to the 8 units per day, which doesn't include heating, cooking or lighting. I know you say 5 minutes for shower per day, but I often say I only had 3 pints when I actually had 5.

A last one worth clearing off the tables is; at night with all the exterior apartment management lighting running, switch off your main switch and check if any hallway or outside lighting goes off. It shouldn't.

Hope this helps.


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## Leo (13 Feb 2006)

The shower is likely to be rated at more than 6kW. Vast majority of showers are 8.5 to 10.5kW, so will use a unit in close enough to 5 minutes. 

You didn't mention hot water either, I presume you have an immersion heater? Put that down for a few units per day. These are generally around the 3kW mark, so can use a unit in 20 minutes.
Leo


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## ClubMan (13 Feb 2006)

I'd agree with SineWave - record the actual electricity usage on the meter for a few days/weeks to gauge what's being registered. If this seems out of whack with the actual loads that you have (immersion, heating, shower, kitchen appliances etc. - all of which should have a _kWh _rating stated on a sticker or whatever) then you can start investigating why this might be. If it is not out of whack then you may just need to start economising and being more energy efficient.


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## fullerand (14 Feb 2006)

Our 2-monthly ESB bill arrived last night and came to 180 euro. I'm not hugely surprised because we'd just bought the place and wanted to be comfortable (it's a 3 bed semi which takes some warming up).

I'm guessing the usual suspects are largely to blame : electric shower, heater, dryer, oven, daytime lights etc. But I'd like to find out the power usage of some of the plug-in appliances, particularly because I leave my computer & cablemodem & wifi router on all day. These don't have a power rating so I can't calculate it myself.

Does anybody know of a device that you can plug into a socket, and will measure the power usage of a device that is subsequently plugged into it?

thanks


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## TarfHead (14 Feb 2006)

Not sure if this is relevant but I'll lob it in anyway ..

I saw a report on the BBC News website a week or two ago about domestic applicances that have stand-by settings. The report claimed that if there were no such settings, the UK National Grid could do with 2 less power stations.

http://news.bbc.co.uk/1/hi/sci/tech/4620350.stm

In other words, leaving your TV or tumble-dryer on stand-by consumes electricity. It serves no technical purpose, just consumer convenience. So power off properly all such devices when not in use. And leaving your TV on stand-by is also a fire risk.

Also, are you making use of night-rate charges (assuming you're metered for this) ?


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## ClubMan (14 Feb 2006)

TarfHead said:
			
		

> In other words, leaving your TV or tumble-dryer on stand-by consumes electricity.


I presume you mean after finishing a wash? Note that it's not generally advisable to put on a washer/drier and then leave it (e.g. leave the house or go to bed) due to the risk of fire. Do people otherwise leave such appliances on standby? I can't see what the convenience is.


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## TarfHead (14 Feb 2006)

ClubMan said:
			
		

> .. Do people otherwise leave such appliances on standby? I can't see what the convenience is.


 
My wife's approach to turning off the TV at the end of the day is to use the power off/on button on the remote, leaving a red light showing on the fron of the TV. I usually do a sweep of the house before going to bed to make sure things are turned off properly.

But to get the benefit of night-rate, we put on the washing machine and tumble-drier and dishwasher at 11:00 and let them run and remain on stand-by until the next morning which, as I write this, makes me realise that we're probably negating the benefit of stand-by. Not to mention the fire risk.

DOH !!

Which raises an earlier question - how to you measure such usage ?


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## ClubMan (14 Feb 2006)

TarfHead said:
			
		

> Which raises an earlier question - how to you measure such usage ?


As mentioned above a couple of times - measure overall use by monitoring the meter reading (readings if day and night meters installed) for a few days/weeks. You can get special plugs adaptors that monitor individual appliances when you want to refine the investigations. However it should really be obvious from the appliances what the heavy loads are likely to be (as outlined above).


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## fullerand (14 Feb 2006)

fullerand said:
			
		

> Does anybody know of a device that you can plug into a socket, and will measure the power usage of a device that is subsequently plugged into it?


I found what I was looking for:

[broken link removed]


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## ClubMan (14 Feb 2006)

I personally wouldn't bother with such adaptors until I had at least logged the meter readings for a while and then investigated which heavy loads are active and when.


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## dam099 (14 Feb 2006)

fullerand said:
			
		

> But I'd like to find out the power usage of some of the plug-in appliances, particularly because I leave my computer & cablemodem & wifi router on all day. These don't have a power rating so I can't calculate it myself.
> 
> Does anybody know of a device that you can plug into a socket, and will measure the power usage of a device that is subsequently plugged into it?
> 
> thanks


 
Are you sure they have no information, I thought this would be compulsory under safety laws? 

The information is not always easily understood but if for example it does not give the watts/kilowatts you can still calculate them if you know the voltage and amps.


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## ClubMan (14 Feb 2006)

An average _PC _would have a _PSU _rated at about 400W. Ignoring the monitor for the moment this would mean that you could run this for 2.5 hours on a single unit (kWh) of electricity costing about €0.14 if I recall correctly. Your router's power usage is likely to be miniscule in the greater scheme of things. Even the _PC's_ usage will pale into significance when compared to thinks like immersion heaters (often 3-6kW - i.e. up to 6 units of electricity an hour), electric heaters (again rated in kWs rather than Ws) and so on. By all means optimise your use of all electricity but you'd be better off initially concentrating on the heavy loads and making sure that you are using these efficiently first then moving onto other appliances.


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## PadraigL (14 Feb 2006)

The best thing to do is switch everything off and go to the meter. There is a dial that should not be spinning if no electricity is being used. If th dial is still turning, you may have left a light on in the attic for example.

TarfHead, you need a special meter (dual meter) to run on night rate tarrif. Did you have this installed?


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## ClubMan (14 Feb 2006)

You could always trip the master switch on your "fuse" board and then check of the meter dial is not spinning. If it is then somebody else may be connected to your meter!


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## paddyc (15 Feb 2006)

Have you checked your bill to see if its was an estimated reading ? Look for an E next to the units

Our last 2 bills (which were also our first) were way over what we used nearly double, we took a reading rang it into them, they then issued a new bill showing their estimate being half of what we used and then our customer reading on top of that!! Don't know who they are trying to fool with the revised etimated usage


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## fullerand (15 Feb 2006)

dam099 said:
			
		

> Are you sure they have no information, I thought this would be compulsory under safety laws?


I'd have thought so too, but there's no ratings at all on my (admittedly Aldi-bought!) PC.

Going by what ClubMan says above, I'll assume that my PC's PSU is 400W, which means that it uses 9.6 units per 24hrs, which at 14c/unit comes to 40 euro per month! 

Thanks for the tips, will keep an eye out for stuff on standby between now and the next bill


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## fullerand (15 Feb 2006)

paddyc said:
			
		

> Have you checked your bill to see if its was an estimated reading ? Look for an E next to the units



Yes, it was an estimated reading, but I checked the meter and they weren't too far off.


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## Leo (15 Feb 2006)

fullerand said:
			
		

> ... I'll assume that my PC's PSU is 400W, which means that it uses 9.6 units per 24hrs, which at 14c/unit comes to 40 euro per month!


 
400W is the maximum power usage, unless you have lots of extras drawing power, your actual usage will be less than that, perhaps even more like the 200W mark. 
Leo


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## ClubMan (15 Feb 2006)

Good point - sorry I didn't clarify that earlier.


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## Delboy (15 Feb 2006)

SineWave said:
			
		

> If the shower was run 4 times a day for 15 minutes, you would have almost come to the 8 units per day, which doesn't include heating, cooking or lighting. I know you say 5 minutes for shower per day, but I often say I only had 3 pints when I actually had 5.


 


			
				Leo said:
			
		

> You didn't mention hot water either, I presume you have an immersion heater? Put that down for a few units per day. These are generally around the 3kW mark, so can use a unit in 20 minutes.
> Leo


 
No, for sure the shower is run less than 5 minutes a day. The GF is always late in the morning and so has no time to stand in there for ages, except maybe the w/e. I go to the gym and shower there in the morning.
Our hot water comes off of the heating which is GAS. We've never switched the immersion on. 

I've convinced the gf to use the old shower, i.e. hose from the mains, for a few weeks to see the effect this has. I already unplug all appliances at night or when not in use so there's nothing on standby. And as I said, all bulbs are the energy savers but even then, we never have lights on when not in the room except for the hall.

It's very hard to get to the meter as it's outside the building, hard to access etc. But I'll try switching off the trip switch and seeing does the meter stop spinning. I'll also get a reading over an average day and w/e.
Will report back.

Thanks for the help


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## ClubMan (15 Feb 2006)

Delboy said:
			
		

> It's very hard to get to the meter as it's outside the building, hard to access etc.


 Really? How does the _EBS _meter reader access it? If it's a matter of the key needed to open the box then these are readily available and normally provided to householders.


> But I'll try switching off the trip switch and seeing does the meter stop spinning. I'll also get a reading over an average day and w/e.
> Will report back.


 That would be a good idea.


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## Leo (15 Feb 2006)

Your central heating circulation pump will be using power as well so, check out its rating, probably 200W plus. 
Leo


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## owenm (15 Feb 2006)

Modern PC's are "energy star" compliant whcih means they run at 15 watts or less when on but not in use, this come to €1.51 per month plus usage of 2 hours per day at max €3.36 comes to a grand total of €9.74. You save €3 euros a month by switching it off when not in use.


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## fandango1 (16 Feb 2006)

All this discussion of charges got me thinking at home last night and I started to calculate how much everything costs to run. Hoping someone will be able to tell me if I am working it out properly....e.g.

The sticker on my fridge says that it 160w which is 0.160Kw. Does this mean it uses 0.16 units of electricity per hour? If so, that works out at 2 cent an hour (based on a rate of 12.73 cent an hour) or 48 cent a day.

Is that correct?


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## fullerand (16 Feb 2006)

fandango1 said:
			
		

> The sticker on my fridge says that it 160w which is 0.160Kw. Does this mean it uses 0.16 units of electricity per hour? If so, that works out at 2 cent an hour (based on a rate of 12.73 cent an hour) or 48 cent a day.  Is that correct?


As far as I understand it, the power rating of your fridge says that the maximum power it will use is 160W.  The amount of power it actually uses while running will depend of various factors such as the internal temperature setting, the temperature of the room it's in, and what food is inside it.

AFAIK the only way to tell for sure how much power an appliance uses over a certain period is to use a power monitor socket like the one I linked to above.  I bought one yesterday and have already proven to my girlfriend that my computer isn't costing us millions!  Worth the investment just for that 

BTW, bear in mind that 12.73 is the cost before VAT - comes to just over 14c with VAT.


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## ClubMan (16 Feb 2006)

Home kitchen appliances should also state (on the EU mandated energy rating sticker normally found on the casing or inside the appliance cavity) their average daily/yearly (e.g. fridges/freezers) or per cycle (e.g. washing machines and driers) running energy consumption in kWhs which is more relevant than the raw W rating when estimating running costs. See here.


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## Delboy (25 Feb 2006)

did a reading over 24 hours as was talked about. Used exactly 6 units.
And I recorded what appliances/lights we used over this period, which was:

Lights - various, about 5 hours in total..all energy efficient bulbs.
Cooker - 2 hobs...20 mins in total.
TV - 8 hours...a lot I know, but i was off sick from work and olympic curling is so addictive!!!!
(the video and dvd would be on standby for this length as well).
Computer - 2 hours (comp is brand new).
Heating 4.5 hours (but is GAS), but uses a timer.
Fridge. (no sticker on this giving power...as it's oldish,maybe 5-7 years, and came with the apt.- but it's on the top temp setting inside)
MISC-Kettle boiled about 5 times. 2 radio alarm clocks.

I switched off the power in the apt and checked the meter - it was'nt moving so it's not external hall lights etc thats feeding off the meter.
We did'nt use the electric shower...stuck to the hose which works off the emersion where the water is heated by Gas. And no washing machine was used either.

6 units seems very high, especially when u look at the leaflet the ESB sent out with their last bill.....
They said 1 unit =:
100 watt bulb for 10 hours
or
electric cooker = cooking for 1 person for 1 day
or
TV = 6-9 hours....

it does'nt add up... any thoughts on this


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## ClubMan (25 Feb 2006)

I you switched off the master switch on your fuse/switch board and you still ostensibly used 6 units in a 24 hour period then it sounds to me like something is up and something/somebody is using your electricity possibly without authorisation. Get the _ESB _out to check it.


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## Delboy (25 Feb 2006)

ClubMan said:
			
		

> I you switched off the master switch on your fuse/switch board and you still ostensibly used 6 units in a 24 hour period then it sounds to me like something is up and something/somebody is using your electricity possibly without authorisation. Get the _ESB _out to check it.


 
no -knocked off the trip switch and checked the meter to make sure it was'nt moving and it was'nt. put the trip back on and then used 6 units in 24 hours which was made up of the appliances etc i noted above...

sorry for the confusion


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## Zeus (25 Feb 2006)

My understanding is that any equipment using a cable with a transformer will use electricity as long as the cable with transformer is plugged in (with power/socket switch on).

e.g. a(my) laptop or mobile phone. So when the laptop is fully charged (green light), the same amount of electricity will still be used as long as the cable with transformer is plugged in (with power/socktet switch on). 

I do not know if the power/wattage of a piece of equipment (e.g a router) refers to the router itself (small) or to the transformer (larger and what you pay for) ?


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## ClubMan (25 Feb 2006)

Delboy said:
			
		

> no -knocked off the trip switch and checked the meter to make sure it was'nt moving and it was'nt. put the trip back on and then used 6 units in 24 hours which was made up of the appliances etc i noted above...
> 
> sorry for the confusion


Oh - that's different so. You must have appliances using the 6 units so. Try switching off *and plugging out *everything and see what happens. Not sure how practical this is for 24 hours this time of the year.


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## Leo (27 Feb 2006)

Zeus said:
			
		

> My understanding is that any equipment using a cable with a transformer will use electricity as long as the cable with transformer is plugged in (with power/socket switch on).
> 
> e.g. a(my) laptop or mobile phone. So when the laptop is fully charged (green light), the same amount of electricity will still be used as long as the cable with transformer is plugged in (with power/socktet switch on).


 
Not true.



			
				Zeus said:
			
		

> I do not know if the power/wattage of a piece of equipment (e.g a router) refers to the router itself (small) or to the transformer (larger and what you pay for) ?


 
Generally applies to the combination. 
Leo


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## Zeus (27 Feb 2006)

Leo, can you expalin why you believe this is not true ?
I would have thought that a transformer using electricity from the socket in one coil would not know whether some equipment is plugged in to pick up the new voltage/current from the other coil (unless newer transformers can do this). 

Could a vailid test be to remove the laptop from the transformer cable which is still plugged in. If the transformer will not use electricity, it will not dissapate heat, if it still uses electicity, the transformer will dissapate heat ?


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## Leo (27 Feb 2006)

Zeus said:
			
		

> Leo, can you expalin why you believe this is not true ?
> I would have thought that a transformer using electricity from the socket in one coil would not know whether some equipment is plugged in to pick up the new voltage/current from the other coil (unless newer transformers can do this).


 
All transformers will have a certain no-load loss, but this is generally negligible and is mainly down to the resistance in the copper used in the windings. This no-load loss will result in a heating of the transformer, as energy can neither be create or destroyed, it must be converted into another energy form. 

Ignoring all losses, the current in the primary coil is directly related to the current in the secondary, so zero current in the secondary results in a zero current in the primary.



			
				Zeus said:
			
		

> Could a vailid test be to remove the laptop from the transformer cable which is still plugged in. If the transformer will not use electricity, it will not dissapate heat, if it still uses electicity, the transformer will dissapate heat ?


 
The only valid test would be to measure the current drawn under full load and no-load conditions.
Leo


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## Delboy (27 Feb 2006)

ClubMan said:
			
		

> Oh - that's different so. You must have appliances using the 6 units so. Try switching off *and plugging out *everything and see what happens. Not sure how practical this is for 24 hours this time of the year.


 
everything that used power in the 24 hours i've listed. must be the fridge...thats all i can put it down to....


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## ClubMan (27 Feb 2006)

6 kWh units per 24 hour period seems high for a fridge. What make/model?

The fridge should have a label on the cabinet or inside the fridge itself detailing its electricity usage in terms of kWh per 24 hours or something similar. My cheap and cheerful (nasty?) _Candy _half and half is a D (energy efficiency) rated appliance and uses c. 1.56 units (kWhs) per 24 hours. Obviously actual usage depends on environmental conditions, thermostat setting etc. but that's a rough guide. More modern and energy efficient applicances should probably use less but some (e.g. _US _style big fridge/freezers) could use more. Check your fridge for this label and see what it says. You could always plug it out for an hour or two and see if the meter stops totally. Presumably your fridge is working OK, is adequately ventilated at the back/sides, doesn't have excessive amounts of dust/dirt on the external elements at the rear (these should be hoovered/dusted every few years to ensure maximum efficiency) etc.


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