use of multi meter to measure power consumption

[notrub]

Can I use a multi meter to measure the draw of a particular item?  As in, measure draw of power on the main panel with appliance off then turn on and measure new level of power going through the consumer unit.  And then the formula to get the reading to a meaningful number to calculate the cost on my Thai electric bill. Please.  In particular, I am trying to confirm the consumption of my sauna heater but the method would work to measure any appliance, I would have thought. ?   Thanks very much in advance for any help.

[bankruatsteve]

No.  You need a watt meter (check out Lazada) or a "wrap around" (inductive) ammeter which includes a volt meter.

[sappersrest]

Is there a late of any description on the heater or panel? That should have the power consumption in watts.

 

[Crossy]

You could use your electricity meter.

 

Turn everything off.

Read the meter.

Run the sauna alone for 30 minutes.

Read the meter again.

 

Double the difference in meter readings will give you the consumption in kW.

 

 

 

[AhFarangJa]

I always learn a lot from these posts regarding electricity , Please forgive my forwardness for a slight hijack to the post, but on a slightly different subject, can anyone tell me how to check my electric meter is running at the correct speed ?

Many thanks

[al007]

A clamp meter is the required tool some do both DC and AC, prices vary considerably

[Crossy]

 

22 minutes ago, AhFarangJa said:

I always learn a lot from these posts regarding electricity , Please forgive my forwardness for a slight hijack to the post, but on a slightly different subject, can anyone tell me how to check my electric meter is running at the correct speed ?

Many thanks

 

You need a known and constant load, a 1kW heater (yes I know we're in Thailand), will use 1 unit in 1 hour.

 

Turn everything off.

Read the meter.

Run your 1kW load for 30 minutes.

Read the meter again.

It should read 0.5 units more than the first reading.

[AhFarangJa]

48 minutes ago, Crossy said:

 

 

You need a known and constant load, a 1kW heater (yes I know we're in Thailand), will use 1 unit in 1 hour.

 

Turn everything off.

Read the meter.

Run your 1kW load for 30 minutes.

Read the meter again.

It should read 0.5 units more than the first reading.

Hi Crossy,

Hope all is well with you.....

Many Thanks. I do not have a heater, but will find something similar with a constant load.

When you think about it then it becomes quite logical doesn't it .......

[kensisaket]

If you are looking for a "time of test" reading you can use a clamp-on ammeter. It will show you the amperage being drawn. Multiply that reading by 220 (voltage) and you will get your time of test wattage (divide by 1000 to get KW).   If you are looking at power consumption over an extended period then follow Crosby's suggestion. 

[little mary sunshine]

Use a propane side heater, much cheaper and heats in minutes

[Monkeyrobot]

Sorry buy stay away from the electrics as sounds like it's not your cup of tea so to speak, I am not having a go at you, I just don't want to read in the news > Farang electicuted trying to read power consumption . Get a electrician to do it for you it for you it will be cheaper than going to the trouble of purchasing a watt meter. But if you still want to do it yourself do what Crossey suggests by turning the mains of and just turning on the particular device. Note to self,do not do it bare footed on a wet floor, better still get your wife to do it. 

[Belzybob]

3 hours ago, al007 said:

A clamp meter is the required tool some do both DC and AC, prices vary considerably

If you want the best and are prepared to pay for it, Google the Fluke 325 clamp meter. Not cheap, but it'll do all you need and last forever.

[Jorgendk]

Google "power consumption meter" They are wery good, and cheap.

[al007]

27 minutes ago, Monkeyrobot said:

Sorry buy stay away from the electrics as sounds like it's not your cup of tea so to speak, I am not having a go at you, I just don't want to read in the news > Farang electicuted trying to read power consumption . Get a electrician to do it for you it for you it will be cheaper than going to the trouble of purchasing a watt meter. But if you still want to do it yourself do what Crossey suggests by turning the mains of and just turning on the particular device. Note to self,do not do it bare footed on a wet floor, better still get your wife to do it. 

I continue to learn, I am a mere 72 plus

 

I have numerous meters

 

Have built a couple of houses here

 

Personally the standards of electrical work here is atrocious, and often way overpriced

 

Buy the right equipment be cautious, and learn

 

As i get older I ask people to do more

 

Recently I wanted to change some halogen ceiling lights from 12 v to 240 volt, I had a local electrician come he hardly knew the difference between AC and DC, he was joining wires with insulating tape he was blowing earthing switches,he was using wires too thin that the acted like heating coils, and caught fire, I asked him to leave

 

I had a bell at the front gate 90 mtrs from the house, I originally installed it with a 12volt wire 90 mtrs to the house on 12 volt to a relay to switch bell on at 240volt, it needed replacing the next electrician rewired it all at 240 volt in such a  way when pushing the bell push you got electrocuted, keeps the neighbours away

 

At least understand so you can supervise, and please contine to learn

[lopburi3]

17 minutes ago, al007 said:

I had a bell at the front gate 90 mtrs from the house, I originally installed it with a 12volt wire 90 mtrs to the house on 12 volt to a relay to switch bell on at 240volt, it needed replacing the next electrician rewired it all at 240 volt in such a  way when pushing the bell push you got electrocuted, keeps the neighbours away

Most doorbells are indeed wired 220v here - and the primary reason I have been using RF battery powered types since they became available.

[al007]

4 minutes ago, lopburi3 said:

Most doorbells are indeed wired 220v here - and the primary reason I have been using RF battery powered types since they became available.

Agreed but when running wire a long way from gate when the wire can be damaged is a danger of open 240 volt wire, even though the wire is inside black water hoze 2 mtrs above ground, I also told the electrician I wanted the relay to stay and for the long run use low risk 12 volt current !!

 

Thailand lovely but a challenge

[lopburi3]

Just now, al007 said:

Agreed but when running wire a long way from gate when the wire can be damaged is a danger of open 240 volt wire, even though the wire is inside black water hoze 2 mtrs above ground, I also told the electrician I wanted the relay to stay and for the long run use low risk 12 volt current !!

 

Thailand lovely but a challenge

I agree and was not suggesting running wire or 220v - replace with radio frequency type switch so no wire required was what I mentioned doing.  The RF signal rings a bell inside home plugged into a wall outlet.  

[humqdpf]

6 hours ago, lopburi3 said:

Most doorbells are indeed wired 220v here - and the primary reason I have been using RF battery powered types since they became available.

Doorbells are wired to the mains electricity in many, perhaps most countries.

 

[lopburi3]

Just now, humqdpf said:

Doorbells are wired to the mains electricity in many, perhaps most countries.

 

Which probably would not be an issue on the door - but here in Thailand homes do not normally have street access without external walls/gates.

[al007]

4 minutes ago, lopburi3 said:

I agree and was not suggesting running wire or 220v - replace with radio frequency type switch so no wire required was what I mentioned doing.  The RF signal rings a bell inside home plugged into a wall outlet.  

Yes just put in electric gates when we built wife said she was the opener, but ten yrs on she likes avoiding the rain, this time I used a long range radio signal to open and close from house and works well, of course we have remotes in the car

[Crossy]

We've sort of drifted off topic, never mind.

 

We had poor luck with wireless doorbells, our gate is just too far from the house. Already had wires running to the gate for the electric opener so I ran a 3-core (0.5mm², the smallest I could find) in the same conduit.

 

12V relay operating the 220V doorbell (actually a 6" fire bell so we can hear it all over the garden), another 12V circuit and relay going the other way from a push in the house opens the gates (again marginal on range for the remote). Over 100m of cable everything works just fine, calculated maximum well over 500m.

 

[lopburi3]

Indeed range can be an issue with wireless doorbells - but these days many provide some idea on package before you buy.  See claims up to 300m for some now on aliexpress.

 

It is relatively cheap and very easy to replace and it could save a friend or a life (but then you should be using RCCD for lifesaving).  

 

Edited July 10, 2017 by lopburi3

[RickFarang]

A note about checking your watt-hour meter with a known load: Be careful that your load is continuous during the test. Things like heaters, clothes irons, and air conditioners cycle on and off, giving an incorrectly low reading.

 

For resistive loads such as heaters you can measure AC current and multiply by the voltage -remember to move the test lead to the voltage position so you don't before measuring the voltage so you don't blow the fuse inside your meter (or worse). For most household loads you need an actual power meter because the volts x current calculation for them has to be done in a different way involving continuous observation of current and voltage at the same time.

[bankruatsteve]

Then there's the power factor that may need consider.  

 

Gate bell, OK but why would anybody need a door bell in LOS?  Hell, nobody even bothers to knock around here - just walk on in.

[sfokevin]

Just because something is rated at a certain wattage... say a 1,000 heater... That is most likely just an estimate... you would need to confirm the wattage with a watt meter before using in a test of you electric meter...

[Crossy]

Obviously, if you want to absolutely verify your electricity meter, you need a proper check meter installed, which is what the authority will do if you ask for a check (and they'll charge for it).

 

For a quick verification that it's in the right ball park using a resistive load (heater, kettle and the like) and relying on the rating plate is about as accurate as you are going to get without proper test gear (and the knowledge of how to use it safely).

 

EDIT Just tested our 1000W 220V kettle with a pukka wattmeter, supply was a convenient 225V, power consumption 1120W. Close enough for a ball-park test but hardly calibrated. For most people finding a reasonably high-power resistive load may prove problematic.

 

EDIT 2 For those who want to get a bit more accurate and have a simple multimeter.

Kettle example.

Boil the kettle (so the element is at working temperature)

Measure the resistance (a 1000W kettle will be about 45 Ohms)

Measure the supply voltage (don't forget to select AC Volts)

Use V²/R to calculate your actual appliance wattage.

 

[MaiChai]

6 hours ago, al007 said:

I continue to learn, I am a mere 72 plus

 

I have numerous meters

 

Have built a couple of houses here

 

Personally the standards of electrical work here is atrocious, and often way overpriced

 

Buy the right equipment be cautious, and learn

 

As i get older I ask people to do more

 

Recently I wanted to change some halogen ceiling lights from 12 v to 240 volt, I had a local electrician come he hardly knew the difference between AC and DC, he was joining wires with insulating tape he was blowing earthing switches,he was using wires too thin that the acted like heating coils, and caught fire, I asked him to leave

 

I had a bell at the front gate 90 mtrs from the house, I originally installed it with a 12volt wire 90 mtrs to the house on 12 volt to a relay to switch bell on at 240volt, it needed replacing the next electrician rewired it all at 240 volt in such a  way when pushing the bell push you got electrocuted, keeps the neighbours away

 

At least understand so you can supervise, and please contine to learn

Yes well. I blame the low/lack of education. Most boys dont complete high school (its not cool, etc). Even the ones that complete high school, god knows what they teach them. Its been like this a long time and unlikely to change any time soon. If you want anything doing properly you end up doing it yourself. Thankfully lots of videos on YouTube to guide you... But do take care with electricity.

Edited July 10, 2017 by MaiChai

[al007]

2 hours ago, MaiChai said:

 If you want anything doing properly you end up doing it yourself. 

Thank you Sir, keep smiling, and be lucky, and yes Electricity like many things ( and Thai ladies) needs to be treated with great respect

 

And then you will have a very good life

 

[RickFarang]

For resistive loads the power factor is 1.0

 

For everything else you need a wattmeter.

Edited July 10, 2017 by RickFarang

[StevieAus]

On 7/10/2017 at 11:41 AM, al007 said:

I continue to learn, I am a mere 72 plus

 

I have numerous meters

 

Have built a couple of houses here

 

Personally the standards of electrical work here is atrocious, and often way overpriced

 

Buy the right equipment be cautious, and learn

 

As i get older I ask people to do more

 

Recently I wanted to change some halogen ceiling lights from 12 v to 240 volt, I had a local electrician come he hardly knew the difference between AC and DC, he was joining wires with insulating tape he was blowing earthing switches,he was using wires too thin that the acted like heating coils, and caught fire, I asked him to leave

 

I had a bell at the front gate 90 mtrs from the house, I originally installed it with a 12volt wire 90 mtrs to the house on 12 volt to a relay to switch bell on at 240volt, it needed replacing the next electrician rewired it all at 240 volt in such a  way when pushing the bell push you got electrocuted, keeps the neighbours away

 

At least understand so you can supervise, and please contine to learn

Maybe I am lucky I have a Thai brother in law who is a qualified and trained electrician and has in the past worked for the PEA and a multinational company

My late father was an electrician and as a former aircraft engineer in another life understand basic electrics

I have observed the brother in laws work over 6 years and compared with what I have seen in Aus have no problem he is very safety conscious and does not cut corners

From what I see it's probably the legislative requirements that are as much of a problem as the shonks