Thinking out loud.

[martin007]

We are going to assume that we use a clamp meter to measure the intensity that runs through a wire.

We are going to assume that the wire supplies electricity to the refrigerator.
We know the volts that are in the electrical network.

Is it possible to calculate the approximate consumption of the refrigerator?

[Burgerman]

Yes. Ohms law tells you everything. Its simple.
You know the voltage, (or can measure this). Lets say its: 230V AC.

You know the current in Amps. In your case your AC Clamp meter shows 1.5 Amps.
So 230 x 1.5 = 345 Watts.

Or 0.345 kWh used (per hour).
So over a 3 hour period that would be a tiny bit more than 1kW hour used.
In a day that would add up to 345W x 24h = 8.2kWh.

BUT sadly it varies over time.
On/off thermostat, defrost (modern fridges have a HEATER in them that heats up the interior a couple of times a day to melt any frost for a short period) etc.
So room temperature and how often you open the door, etc all change the daily kWh consumption.

So I have a few of these:
They count up watts, kW/hours, read voltage, current (amps) etc over time as needed to keep track.
https://www.amazon.co.uk/watt-meter/s?k=watt+meter

[martin007]

To what extent are these meters reliable?

Do you trust those meters?

[Burgerman]

That depends on the meter.

Mine is extremely accurate. AC and DC and single digit mA capable.
I can use my calibrated fluke test meter in a circuit and even at really low values like 5mA it reads pretty much the same. As long as you ZERO it. And thats DC. But it wasnt cheap.

On AC its just as accurate if not more so as local magnetic fields dont change its readings. So less need to zero it before a measurement.

Unless you mean these: https://www.amazon.co.uk/watt-meter/s?k=watt+meter
In which case I am not sure.

But...
You also need to understand the difference between actual power and real power. Look up also power factor. It wont affect your fridge reading much but some power supplies etc dont give accurate readings. Things that use capaciors on the supply.

[martin007]

Which meter do you recommend?

[Burgerman]

To measure down to LOW currents, reasonably accurate, and be DC capable used to cost a fortune.

This isnt expensive.
Look on eBay etc.

And does all of that.

https://www.markhennessy.co.uk/budget_m ... ut210e.htm

[martin007]

I already knew the quality of the manufacturer UNI-T.


Do you know any current meter with memory that can save the readings you make over a period of time?

For example, the clamp meter is left for as long as the night and to note the intensities...

[Burgerman]

Yes my fluke 289 and a current clamp. You wont like the price.

Also for this job a cheap wall plug watt meter as linked above works best.

I also use these:

Watts, remotely. Watt Hours. kWh. Amps, mA, Volts, and you can remotely turn things on and off.

I hate phones, but have to have one and so I have 12 of these. It monitors almost everything important. And allows me tu turn things off or on.

Keeps track by hour, day, month, year etc. Adds up usage and shows you graphs.