5Amp/15Amp Meter Readings . Same Or Not

[silentnine]

Hi All

i have fitted an extra private meter on part of my upcountry house

the incoming goverment meter is a 5amp

i wanted to see how much electric a very large water pump we have uses so fitted its own meter inline

i could only get a 15amp meter from the local hardware shop

what i cannot now understand is the 15amp meter showed we used 16 units(on the pump) this week but the goverment meter indicates over 200 total usage

i know that over 80% of the total electric used is for this big pump so numbers to not match

do the readings of a 5amp meter differ from that of a 15amp ?

i initially thought the difference was maximum load so did not matter if it was not the same as the main meter, however on thinking about it being that meters are not fused i now think it relates to the reading

if so is there an equation to convert what a 15a meter read to what a 5a would so i can tally it up

[candid]

_{Are you sure the "government meter" is not reading 20.0 units}

[silentnine]

_{Are you sure the "government meter" is not reading 20.0 units}

sure..

average bill is 4900bt .. as i said its a big pump

so 200+ units is about right

[Jdietz]

So let's turn the question around then...

Are you sure your own meter isn't reading 160 units?

[David006]

gotta ask why fit another meter? If you know the wattage I am sure one of the sparkies will confirm or deny ( probably a chart someplace?) but it should not be too difficult to calculate within a few units ? Or just turn off everything in the house and run the pump for 10 minutes and check the PEA meter?

Would think that the meters should not register differently.

[Crossy]

Post photos of the two meters, easiest way for us to determine what's what.

Yes they should read the same.

[bdenner]

I was conned into replacing our 5 AMP meter (we were always running close to the limit (don't have A/C)) with a 15 AMP by the authority them saying my consumption reading will reduce with a meter designed to run within the range I use, obviously more than the average village dwelling. Well over the past 4 months the KWH readings are up at least 5 % and coming into the cooler months they should fall. So bottom line, lesson learned, should have saved my 3700 baht conversion fee.

[silentnine]

Post photos of the two meters, easiest way for us to determine what's what.

Yes they should read the same.

will take photos of them both when i'm back there in a few days . ty

So let's turn the question around then...

Are you sure your own meter isn't reading 160 units?

yes very sure.

i checked them both several times daily for a week. both meters have 4 main digits and the fraction digit..

the main meter flys round very quick on the spinner and my secondary meter is going round a lot slower as in say 10% of the speed of the other

i've checked my wires to make sure the load i'm measuring is all going thru the secondary meter .. that being when on full load 1*1,5kw pump, 1*1kw pump, 60*35w pumps & 16 * 25w light bulbs

gotta ask why fit another meter? If you know the wattage I am sure one of the sparkies will confirm or deny ( probably a chart someplace?) but it should not be too difficult to calculate within a few units ? Or just turn off everything in the house and run the pump for 10 minutes and check the PEA meter?

Would think that the meters should not register differently.

i have a lot of things running as its a hydroponics farm with a commercial reverse ozmosis system and other big pumps. so want to separate segments for cost analysis

i mainly want to put separate meters for the larger high power pumps. then the 60+ small pumps and another for lighting

i am failing at step 1 with a main secondary meter lol

[Jdietz]

Just for a ballpark figure, about how many hours have you been running that big pump this week?

An 1.5KW pump at full load should use at max ..tadaa.. 1.5 units an hour.

Both meters should have a plaque stating how many revolutions of the spinner amounts to 1 kWh (1 unit), so to make sure they work correctly sit and watch for a bit.

At max load (everything on, pumps actually running flat out) you should be using about 5KW, so 5 units every hour.

When all this checks out, indeed, please pictures of both meters and wiring diagram, we'll figure it out.

[silentnine]

Just for a ballpark figure, about how many hours have you been running that big pump this week?

An 1.5KW pump at full load should use at max ..tadaa.. 1.5 units an hour.

Both meters should have a plaque stating how many revolutions of the spinner amounts to 1 kWh (1 unit), so to make sure they work correctly sit and watch for a bit.

At max load (everything on, pumps actually running flat out) you should be using about 5KW, so 5 units every hour.

When all this checks out, indeed, please pictures of both meters and wiring diagram, we'll figure it out.

will post pics later today when i get there ..

elecrtic in the village is not very good.

the whole road power drops (visible light dimming in all the other houses) when i start the main pump and the starter kicks in for 10 seconds !

[electau]

Metering. A 5/15 amp meter which is supplied and is the property of the PEA measures the energy in kWhours of all of your electrical installation. On the nameplate will be the revolutions per kWh, this is based on a test current of 5 amps. the second figure of 15amps is the normal continuous load current that the meter will sustain without affecting accuracy.

The current coil will sustain currents in excess of 100% of the rated figure. All that will occur is that the disc will run at high rate of revolutions.

With a 15/45 amps meter the above applies except that the revolutions per kWh will be less, and the meter can sustain higher currents. The test current here is 15amps.

You wish to meter the pump circuits to determine the consumption in KWhs. You do not touch the existing PEA meter. The submeter 15/45 is connected where the pump circuits originate at the switchboard. The line side of the meter ( the left terminal) is connected to the supply and the subcircuits to the MCBs for the pumps are connected to the load terminal, the right hand terminal. The neutral (the center terminals) is connected to the neutral link or bar with a 2.5 or 4.0 sqmm single wire, as this only for the voltage coil of the meter.

When the pumps are running the consumption will be recorded by this meter for the pumps only unless you have other load connected.

The PEA meter will still record the total consumption of the installation and the consumption by the pumps.

To read a meter. Read from left to right on the counter, (10000) (1000) (100) (10) (1). the last digit in tenths of a kWh is not read. Eg. 47387.

You can check this on your electricity account.

Edited November 5, 2012 by electau