A strange Meter question

[h90]

On the Zero line some voltage comes, which is normal I guess.

We have the Zero connected to Earth cable.

Now the big question: do we pay for the electric that goes from Zero to Earth?

Crossy once teached me that when the electric goes L to Earth the meter runs the same as if it would go to the Zero. But what is with the Zero?

[Crossy]

A conventional (rotating disc) meter has three coils:-

One across L-N to measure the voltage

One in series with the Live to sense current

One in series with the Neutral also to sense current.

These coils, in conjunction with the aluminium disc form a small induction motor.

The physical relationship between the coils and the action of a small permanent magnet providing a braking force means that the speed at which the disc rotates is proportional to the voltage and the sum of two current coils multiplied by the Cosine of the phase angle between the voltage and current waveforms (the Power Factor).

Now if the neutral is slightly above ground a small current will flow from the supply neutral to the ground rod. BUT this current will be in the opposite direction to which the normal neutral current flows and will tend to turn the disc backwards reducing the reading (and thus the bill).

In practice the reverse flow is so small that with no load the torque cannot overcome the 'stiction' in the mechanism and the meter does not move, but even if it did it would move backwards.

So no you don't pay for that energy.

https://en.wikipedia.org/wiki/Electricity_meter

[dinga]

Here's another strange question for Crossy...

What is the difference between PEA Meter Types 1125 and 2125 (I've been told the former is OK for the Solar

Home programme but the latter - which I have - is not). Seems very odd as my next door neighbour (virtually identical house has a 1125)

[Crossy]

Is there any indication of the manufacturer on the meter, that would help identify what the differences are.

It's possible that the 2125 has an anti-fraud mechanism that stops it spinning backwards, another reason that you need to be in touch with your supply authority when installing solar, even if not on an export tariff.

[dinga]

Am told by the Solar supplier -

Meter 1125 = 5-15/45Amp = residential

Meter 2125 = 30-45/100Amp = commercial

Gawd only nose why our modest bungalow has a commercial meter (wonder if our unit rate is higher?). Will be contacting PEA tomorrow to see if the meter can be changed to Type 1125 in time to participate in the Solar House programme

[IMHO]

Where are you seeing the "2125" marking?

[dinga]

Cant' see it marked on the meter, but 2125 is shown as the Meter Type on the monthly PEA bill.

Edited June 21, 2015 by dinga

[blackcab]

If you downgrade your meter ask about the deposit. On our commercial properties we have (if I remember correctly) 200 amp meters. I know for a fact that we had to pay the MEA a refundable deposit of 48,000 baht per meter.

I'm not sure if residential properties have to pay a deposit, but it's worth querying to see if you can get a partial refund.

[dinga]

If you downgrade your meter ask about the deposit. On our commercial properties we have (if I remember correctly) 200 amp meters. I know for a fact that we had to pay the MEA a refundable deposit of 48,000 baht per meter.

I'm not sure if residential properties have to pay a deposit, but it's worth querying to see if you can get a partial refund.

Tks - will ask, but no way would have I paid such deposit when they replaced the dead meter a couple of years ago!

[blackcab]

Our meters are for apartment blocks and the monthly bill is a bit higher than residential use.

I was thinking you might be able to extract enough to cover the cost of a few beers

I know it might not be a lot in the scheme of things, but better in your pocket than theirs.