Difference in amperage though household meter question

[Cheshire man]

Hi,
I have just joined as I have a non urgent but nagging question...hope you guys can give me peace of mind!
Thank in advance.
I have just checked the amperage coming in on the meter tails prior to the meter (Between the main fuse and the old style dial meter) this is 0.85 amps. However the measured amperage in the tails between the meter and the consumer unit (actually between the meter and an old 50mA RCD that then goes onto the consumer unit) this is 0.97 amps. Why the discrepancy?
Any thoughts/revelation or 'that should be bleeding obvious mate' answers?

 

[alasdairp]

I'm not saying power factor is affecting the readings, rather that it is responsible for the apparent anomaly that the input current to the meter is lower than the output current. My theory is that each reading is correct in itself, and the input current is indeed lower, but since the voltage coil magnetising current is heavily lagging, if the house 'standby' current is leading then subtracting the meter output current from the meter input current can yield a negative result even while both the house and the meter coil apparent power is positive. If the OP replies and confirms that we've understood correctly, I'll draw a phasor diagram.

Ah, I now follow. IF (quite a big if in my opinion) the inductance of the meter coil is enough to improve a bad capacitive PF and move it closer to unity, then the current on the supply side will be lower for the same total power. Yes, that is true. It would be very interesting to measure and calculate the PF in both places.

I may have a play with an old meter and some low current capacitive loads over the w/e.

 

[ChipFanDave]

Hi,

Its a TT system but it does not have a dedicated earth rod. Its earthed via the old copper going into lead mains water pipe. I am the only person on my estate still on lead and I have it all to myself and I have a long drive so there is plenty underground.

I don't think you should be using the water supply pipe as your earth electrode. 542.2.6

 

[davesparks]

I don't think you should be using the water supply pipe as your earth electrode. 542-02-04.

In a new installation this is unlikely to be allowed, but at the likely age of the installation it was a requirement of the regulations that an earth wire be connected to the metallic water supply pipe as a means of earthing.

 

[ChipFanDave]

In a new installation this is unlikely to be allowed, but at the likely age of the installation it was a requirement of the regulations that an earth wire be connected to the metallic water supply pipe as a means of earthing.

Could be it was installed before 1966 ?

 

[ruston]

And if my memory serves me , a private water supply pipe could, and I think can still be used.

 

[ChipFanDave]

"I am the only person on my estate still on lead and I have it all to myself "

Unlikely to be private on a housing estate though.