Electric Meter Calibrate ?

[pattayapip]

I live on a small parcel of land with 11 other identical dwellings, all the other dwellings have a single phase electric supply, Mine has a 3 Phase supply, but all our dwellings are billed from a single Main meter, with individual meters on each house to calculate what each dwelling uses.

Now obviously everyones bills are slightly different according to what they use, but my place is nearly double everyone elses bill, about the average for the 3 Bedroom places is 300 Units (Kw/hr ?) per month, mine is 300 just running itself, 500 to 600 when i am home and using air con etc, Twice what everyone elses is even though they have basically the same inside as mine, its just that i have this 3 phase power supply (dont know why, electrician said was best)

Is there any way to have my meter checked ? or do i have to buy a new one to try ? I just cant see how it is possible for my bill to be twice what everyone elses is using basically same equipment ?In My last house i had exactly the same set up and total bill was 1500/1800 per month having aircon on every night, This new place has exactly the same except a larger water pump (Grundfos on a flow actuator) and a higher powered instantaneous water heater for the main show (Redring 10 Kw, but knocked down to run on 1 element as too hot) apart from that everything the same, but my bill here is 1500 when house not used, and 3000 when used ? I think it just has to be the meter over reading, any help advice please ?

[jubby]

The Bills 1500 when the house isn't used ! ?

Surely it should be more like 300 or so, if you have a fridge on when your away.

The 3 phase shouldn't matter, they probably charge you a bit more per unit.

I don't know about calibration, I suspect you'd have to be very persistant with the Electricity company to get them to take any action.

Why not do a quick test yourself.

Turn off all appliances and check the Meter. It shouldn't be moving.

Then turn on a few appliances which you know take a certain amount of power, such as a few fans. 60watts each, so 3 fans should be about 200watts. See how many watts are actually used on the meter over an hour period. It should be accurate enough to identify a problem or not.

[longball53098]

Definitely start by switching everything off at the panel,,,,,,,,,,just switch off the main breaker and then go look at the meter and see if it's moving. If so they have wired in another load between the meter and your panel. If you can and have some knowledge of wiring maybe trace(follow) the cables from the meter that head towards your panel and maybe you can see if any connections are made that go off in another direction.

As said if the meter does not turn when you have things switched off then go back in to the breakers and turn all of them off and switch only the main breaker "on" and again see if the meter spins. It should not.

As stated above then if things seem normal you can switch on only one or two breakers that power up known loads and you can monitor the meter for a given period of time to check if it registers close to the use of the load you have operating. You will need to know the power usage of those appliances or whatever that are in operation. The numbers on the meter are kilowatt hours of use.

[pattayapip]

Definitely start by switching everything off at the panel,,,,,,,,,,just switch off the main breaker and then go look at the meter and see if it's moving. If so they have wired in another load between the meter and your panel. If you can and have some knowledge of wiring maybe trace(follow) the cables from the meter that head towards your panel and maybe you can see if any connections are made that go off in another direction.

As said if the meter does not turn when you have things switched off then go back in to the breakers and turn all of them off and switch only the main breaker "on" and again see if the meter spins. It should not.

As stated above then if things seem normal you can switch on only one or two breakers that power up known loads and you can monitor the meter for a given period of time to check if it registers close to the use of the load you have operating. You will need to know the power usage of those appliances or whatever that are in operation. The numbers on the meter are kilowatt hours of use.

Ok Step 1, Turned off electric at Consumer Unit, All good no problems or usage so nothing is connected in there that should not be there

Step 2, Went out for the night and left Fridge Feezer on as Normal 1 Large Fridge Freezer and 1 Medium Chest feezer, 4 Low wattage Type Bulbs outside = 4 Hours 45 Minutes and the House used exactly 2 Units (Kw/Hr ?) seems alot, as in 24 Hours this would equate to 10.1 Units Therefore 300 Per Month without doing anything !!!

Step 3, Went out again exactly as before but unplugged the Fridge Freezer and the Chest Freezer, same 4 Lights on as before = 4 Hours 30 Minutes and House used exactly 1 Unit which equates to 5.33 in 24 Hours Therefore 160 per Month

So Therefore Fridge Freezer etc using 140 Units a month is that about right ? Would this make you think that the Meter is definately over reading ? As the only option i can see is Buying a New Meter to check ?

What to do now ?

[jubby]

Can you tell us what wattage the lightbulbs are . probably says the wattage on the cap. ?

1 unit over 4.5 hours means the bulbs are using about 55 watts each. Its possible but my outside lights use about 18watts.

The fridges and freezers are not so easy to work with as I believe the power draw is variable.

Edited March 8, 2009 by jubby

[jubby]

The fridges do seem to be using a lot of power though. probably 3 times what they should use. I do suspect your meters running 3 times faster than it should. Check those bulbs and if they are 18 watts that confirms my suspicion.

[pattayapip]

Can you tell us what wattage the lightbulbs are . probably says the wattage on the cap. ?

1 unit over 4.5 hours means the bulbs are using about 55 watts each. Its possible but my outside lights use about 18watts.

The fridges and freezers are not so easy to work with as I believe the power draw is variable.

Just checked my bag of spare Bulbs, and the biggest i have is 20Watt long life Bulbs so they cannot be any more than that, so really means my meter is way over reading ? or something else is drawing off ? I guess i must do same again but isolate everything through consumer unit ? But we were not in obviously and nothing was left switched on except for what i said

Cheers

[jubby]

Do another test tomorrow with just the 4 Bulbs on. make sure nothing else is on, physically check around the house.

If the tests the same go and speak to your local lecky office and give them the evidence.

I recently had to pay back on what they suspected was a slow running meter. We came to a compromise but I did have to pay something so this should work in reverse. They owe you a load of beer tokens. Enjoy them

[pattayapip]

Do another test tomorrow with just the 4 Bulbs on. make sure nothing else is on, physically check around the house.

If the tests the same go and speak to your local lecky office and give them the evidence.

I recently had to pay back on what they suspected was a slow running meter. We came to a compromise but I did have to pay something so this should work in reverse. They owe you a load of beer tokens. Enjoy them

I will isolate everything at the consumer unit apart from 4 Lights and see, Cheers

[tjo o tjim]

How old are the fridge and freezer? Do they cool down to the lowest setting? If the compressor is on continuously, the readings seem believable to me. This can happen if there is a refrigerant leak, if your seals are worn, or if the coils are very dirty.

Another potential problem is that only the air-con units are three phase, so you have a significant imbalance when you are running just the essentials. How is your consumer unit set up? Can you tell if the loads are balanced across the three phases?

Best solution is to get a clamp on ammeter (or have an electrician come by with one) and check what your current and voltage are on each phase.

[longball53098]

i agree with tjo about a possible load imbalance^^^^good thought on his part. Also you mentioned that you had a high powered shower heater?

Do you know if the heater and aircon units are 3 phase or single phase?

Where's Crossy when we need a real knowledgeable answer?

As tjo said an clamp on amp meter would be nice here to see what loads you are running on the phases.

[pattayapip]

i agree with tjo about a possible load imbalance^^^^good thought on his part. Also you mentioned that you had a high powered shower heater?

Do you know if the heater and aircon units are 3 phase or single phase?

Where's Crossy when we need a real knowledgeable answer?

As tjo said an clamp on amp meter would be nice here to see what loads you are running on the phases.

I will have to get an electrician to check Balance then, as i really have no idea I have to fly away on Business in the morning for a few weeks, so it will have to wait, i have no answer or clue about the Aircon, but i can ask the Installer/supplier no problem, everything is only a few months old 3 at the most, including Fridge Freezer. I dont hear the motor coming on in the fridge unless i open the door.

The High Powered shower heater is only on when shower used, and actually i have changed this to only using 1 of the two elements as was just too Hot! Not sure i understand the load balancing ? Sorry But all i know is something just has to be wrong somewhere, its not the cost, it is just that i had the same (99%) in last place and useage nothing like here, i just want to get to the bottom of it and sort it out, if everything turned out to be ok then so be it, i just dont understand how it can be ? So can someone explain the load balancing on the 3 phases easily for me ?

[Rimmer]

Load balancing can be simply explained, I think the following example might help:

1 x Air con and three lights on the yellow phase

1 x Air con and a water heater on the blue phase

2 x fridges 1 x freezer and 2 x water heater on the red phase.

Ideally each phase should be around the same total amperage loading spread three ways instead of one big chunk of load all going into to one phase, one set of bus bars and one cable.

Edited March 10, 2009 by Rimmer

[longball53098]

If we take this loading question a bit farther what is the result of not balancing the load? Say you load one phase up with high current draw and the other 2 have very little. Let's say for example on a 15 (45) amp 3 phase service we load phase A with 40 amp load and phase B & C only have 10 amp load. What is the result? Will the meter still calculate correctly?

[jubby]

If we take this loading question a bit farther what is the result of not balancing the load? Say you load one phase up with high current draw and the other 2 have very little. Let's say for example on a 15 (45) amp 3 phase service we load phase A with 40 amp load and phase B & C only have 10 amp load. What is the result? Will the meter still calculate correctly?

I'm no expert on Electrics but surely, 1 unit is 1 unit i.e. 1 killowatt consumed . 1 killowatt consumed no matter wether you have 1 phase or 3. The test on the 4 lights seem to indicate that his meter is 3 times too fast. Whats it got to do with 'Load balancing' 4 lights = 80watts . No load at all. I think he needs to speak to the 'lecky' company.

[longball53098]

If we take this loading question a bit farther what is the result of not balancing the load? Say you load one phase up with high current draw and the other 2 have very little. Let's say for example on a 15 (45) amp 3 phase service we load phase A with 40 amp load and phase B & C only have 10 amp load. What is the result? Will the meter still calculate correctly?

I'm no expert on Electrics but surely, 1 unit is 1 unit i.e. 1 killowatt consumed . 1 killowatt consumed no matter wether you have 1 phase or 3. The test on the 4 lights seem to indicate that his meter is 3 times too fast. Whats it got to do with 'Load balancing' 4 lights = 80watts . No load at all. I think he needs to speak to the 'lecky' company.

That was kind of the point to my question about what will the meter do if the load is not balanced. I think the meter could care less about balance. A kilowatt through the meter on any leg of the 3 phase will turn the meter.

He needs to find out what if any load is making the meter spin and do some calculating to find out if the meter is accurately recording the draw. It may indeed be a defective meter. The lights on should be a good test because it is a constant draw not like an AC or fridge motor. If you turn on 10 one hundred watt lights for 1 hour that should move the meter one unit or one kilowatt hour. So if his meter reading is say "3457.2" after one hour it should be "3458.2"

I think I did all this correct. It's still early and the brain is not in gear yet.

[Crossy]

Pretty much everything said above is wise

Do a controlled test with constant load (unplug the fridge or open all the breakers except the one with your test load on it), 1000W for 1 hour should use 1 unit, easy. The longer you test for the better the result, if you have 500 or 1000W of lamps then that would be a good start.

For a quick check, you can time the rotation of the disc in the meter over say 5 or 10 revolutions. There should be a label saying how many revs per kWh. From this you can work out the load the meter thinks is attached and compare it with the load you know is attached.

Even a severe load imbalance should not significantly affect the accuracy of your meter, however, a serious voltage difference between the phases may.

Edited March 11, 2009 by Crossy

[pattayapip]

Pretty much everything said above is wise

Do a controlled test with constant load (unplug the fridge or open all the breakers except the one with your test load on it), 1000W for 1 hour should use 1 unit, easy. The longer you test for the better the result, if you have 500 or 1000W of lamps then that would be a good start.

For a quick check, you can time the rotation of the disc in the meter over say 5 or 10 revolutions. There should be a label saying how many revs per kWh. From this you can work out the load the meter thinks is attached and compare it with the load you know is attached.

Even a severe load imbalance should not significantly affect the accuracy of your meter, however, a serious voltage difference between the phases may.

Hi Guys, Well i got back from work and did yet another test last night, 15 20 Watt lights on for 4 hours, everything else isolated at the consumer unit. Just over 1.1 Kw/Hr used, so Meter apparently is reading fine !! So with that test everything was isolated through the consumer unit, so now need to do a few more tests isolating in the same way, but meter apparently fine. Am just going to have to work my way round the house room by room isolating properly and see what i find, its confusing this

[Crossy]

Hi Guys, Well i got back from work and did yet another test last night, 15 20 Watt lights on for 4 hours, everything else isolated at the consumer unit. Just over 1.1 Kw/Hr used, so Meter apparently is reading fine !! So with that test everything was isolated through the consumer unit, so now need to do a few more tests isolating in the same way, but meter apparently fine. Am just going to have to work my way round the house room by room isolating properly and see what i find, its confusing this

Meter OK! That is one variable to tick off

Take the scientific approach and you WILL discover where your electricity is going (at least you now know it's going somewhere)