Why did this happen ?

[Ginvariant]

OK, 1st post and I admit it will seem unbelievable, but here goes:
Some details first. My wife and I live in an average size 1960s 3 bed detached bungalow with a single phase 80amp TNS
supply. Gas central heating but all electric cooking with standard white goods - no car chargers, hot tubs, patio heaters or anything like that.
About 10 years ago our electricity supplier (EON) sent out an annual usage summary that revealed usage in the previous 12 months had been over 10,000 Kwh. I thought there must be some mistake, and dug out some paper copies of bills
going back a year or two which were all in the 10 - 12000 Kwh/year range (I agree I should have noticed sooner).
This seemed an incredible amount of electricity to be using, and I thought the new meter that had been installed a couple of years earlier was at fault, so I insisted EON installed a checkmeter, which they (reluctantly) did. The DNO also changed the fuse carrier/head at roughly the same time, as the pitch insulation was leaking from the old one.
My initial disappointment at seeing both meters record almost identical readings quickly improved when I realised our usage was now much more reasonable, and in fact in all the years since we have never exceeded 5500Kwh/year. Now I admit we had a 'put that light out' campaign, but a saving of 5000Kwh ???
This has been nagging away at me for years, so having discovered this site I wondered if any professional electricians out there had any ideas about where all the electricity went ?

 

[littlespark]

So did changing the head save you 5000, or deliberately trying to save electricity by turning things off?

I maybe shouldn’t need to tell you… but there are ways to work out what circuit may be causing overuse. Will take some time, so be patient.

Everything off, take a meter reading, wait an hour.. take another reading. See If there’s a difference.
Repeat with each circuit on, one at a time.

Something will crop up.

 

[telectrix]

5000kWh/year is approx 96kWh/week which equate to a shower on for a few hours, a 3kW oven for a few, and lights and other equippment as and when. . equates to around £20/week which is average for a smallish dwelling. (that's before the price rise).

 

[Ginvariant]

Thanks for taking the trouble to reply, and don't worry I'm always open to advice.
The difficulty is none of the circuits have changed in any meaningful way over the years. Yes, replacement white goods are hopefully more efficient and we now use led lighting, but we haven't suddenly stopped our arc welding hobby because we never did it in the first place. I am genuinely at a loss as to how a 'saving' of 5000Kwh occurred, and lean more towards the idea that there was a fault that was fortuitously corrected. But are there any 'upstream' faults that can affect meter readings ?

 

[telectrix]

or could next door be tapped in?

 

[Ginvariant]

5000kWh/year is approx 96kWh/week which equate to a shower on for a few hours, a 3kW oven for a few, and lights and other equippment as and when. . equates to around £20/week which is average for a smallish dwelling. (that's before the price rise).

Sorry, should have made it clear that the gas boiler also supplies the hot water.

 

[Ginvariant]

or could next door be tapped in?

Detached bungalow, so a bit of a stretch in more ways than one !

 

[brianmoooore]

5000kW/hr per year equates to a constant consumption of around 570W. Not impossible to save by a targeted campaign if you weren't too careful before, but on the limits of what's believable.
If it were a single 'fault' above ground consuming that sort of power, the heat produced would have given it away.

 

[Ginvariant]

5000kW/hr per year equates to a constant consumption of around 570W. Not impossible to save by a targeted campaign if you weren't too careful before, but on the limits of what's believable.
If it were a single 'fault' above ground consuming that sort of power, the heat produced would have given it away.

Your logic is impeccable, and probably what I would have said if the situation was reversed. I just find it very hard to believe anything we did could have had such a dramatic effect. However, if you can categorically rule out an upstream fault (phasing issues ?) then, like Sherlock Holmes, I (reluctantly) have to accept what's left must be the explanation.

 

[MJPD29]

Did you use any plug in electric heaters? Or change a few 50w halogen spots to led? Or even a few 100w lamps to led? Generally the energy consumption of most appliances has also came down in recent years, so if you've got relatively new white goods that could also contribute to it.

 

[nicebutdim]

One of the appliance changes didn't involve getting rid of a vented tumble dryer?

 

[Ginvariant]

Did you use any plug in electric heaters? Or change a few 50w halogen spots to led? Or even a few 100w lamps to led? Generally the energy consumption of most appliances has also came down in recent years, so if you've got relatively new white goods that could also contribute to it.

There are a couple of 3kw heaters in the conservatory, but they are rarely used and they are still there. I have changed some halogens to led, but only in the last 12 months, Believe me, I have racked my brain trying to think of things that have changed and nothing comes anywhere near explaining 5000Kwh.

 

[MJPD29]

There are a couple of 3kw heaters in the conservatory, but they are rarely used and they are still there. I have changed some halogens to led, but only in the last 12 months, Believe me, I have racked my brain trying to think of things that have changed and nothing comes anywhere near explaining 5000Kwh.

Interesting. Nothing suspicious going on in the attic either that may have ceased trading?

 

[pc1966]

5000kW/hr per year equates to a constant consumption of around 570W. Not impossible to save by a targeted campaign if you weren't too careful before, but on the limits of what's believable.
If it were a single 'fault' above ground consuming that sort of power, the heat produced would have given it away.

If it were dumped in to some earthed object of ~93 ohms and no RCD protection to notice, then it could go on for years and be largely unnoticed.

Of course it could just be usage patterns on other high power appliances, but if the house electrics has no EICR for the period concerned it might be worth getting it systematically tested to rule that out. And to have RCD protection fitted if none present!

 

[Ginvariant]

One of the appliance changes didn't involve getting rid of a vented tumble dryer?

No, we've never had a tumble dryer.

 

[Ginvariant]

CU is a mid 80s MK Sentry with a 4 module 100mA ELCB as the main switch, so it would have tripped on a 93ohm short to earth.

 

[brianmoooore]

Are there many downlighters in your house? One of my sister in laws has ten downlighters in her kitchen that were rarely turned off between first thing in the morning and last thing at night. They were fitted with 50W halogens, but have now been replaced by 5W LEDs, so a saving of 450W for about 16 hours a day.
This alone averages out to a continuous saving of around 300W, or around half of what you have saved.

 

[pc1966]

CU is a mid 80s MK Sentry with a 4 module 100mA ELCB as the main switch, so it would have tripped on a 93ohm short to earth.

Yes, true.

Providing it is working. Have you trip-tested it recently?

 

[Ginvariant]

Yes, true.

Providing it is working. Have you trip-tested it recently?

Yes, within the last couple of months and numerous times over the last 10 years, most of which were with the test button ;-)

 

[pc1966]

Yes, within the last couple of months and numerous times over the last 10 years, most of which were with the test button ;-)

Excellent!

Few people even know there is a test button, let alone use it regularly!