Ampage

[lingnoi1977]

I am having a house built in a moo-baan in Chiangmai and the house comes standard with a 15 amp single phase power board.

This would be ok for a small Thai family with no real kitchen. We have a full western kitchen, 4 air con's, etc etc. Obviously not all the applicances will be on at once.

My question is, if we upgrade to 3 phase and increase the ampage, what amount is sufficient? As a general rule, will 40-50 amps be ok for a 3 bedroom house?

Thanks, Lingnoi.

[powderpuff]

Why do you feel you need 3 phase power?

I have a similar house to yours. I ordered a 30/100 amp meter from MEA. Load center is 100 amp main breaker.

You might get away with 63 amp - depending on what size air cons you want to install. The next smaller size power meter is 15/45.

But I have storage water heaters, 4000 watt cook stove , water pump, big hi-fi etc. 7 air cons.

[mdechgan]

I use 15/45 amp meter and regret it everyday. I should have installed a 30/100 amp. Now I have to put up something like an extra 9 - 10,000 baht for a new meter. Should have requested a 30/100 amp in the first place.

[longball53098]

30/100 should be plenty of power but you should really do a Maximum Demand calculation to know what you really will be pulling in the way of amps.

Some developments will only allow a max meter size of 15/45 be it single or 3 phase as the development cabling and transformer will only support this size meter. Such is the case where I built. When I requested a 30/100 they said cannot only can do 15/45.

[Crossy]

Yup ^^^ do a maximum demand calculation (do a search there's a couple of threads).

If it comes out over about 50A (assuming you can only get a 15/45 meter) then it's 3-phase time.

[mdechgan]

Yup ^^^ do a maximum demand calculation (do a search there's a couple of threads).

If it comes out over about 50A (assuming you can only get a 15/45 meter) then it's 3-phase time.

Is a 30/100 amp single phase or 15/45 3 phase better?

[Crossy]

Yup ^^^ do a maximum demand calculation (do a search there's a couple of threads).

If it comes out over about 50A (assuming you can only get a 15/45 meter) then it's 3-phase time.

Is a 30/100 amp single phase or 15/45 3 phase better?

15/45 3-phase can potentially provide 50% more power, but do consider whether you really need it

[bankruatsteve]

I've had 30/100 service with 4 A/C units and, most times, if I turn them all on, the voltage drops, the lights dim, etc. That's single phase service. So, I suppose it depends on what your local supply can supply. Obviously, 3-phase could help, but I wouldn't want to pay for it.

[Pib]

I've got 30/100A single phase service here in Bangkok with 7 (seven) split-air A/C units (all 4 upstairs bedrooms has an A/C plus 3 A/C's downstairs), usually with 2 A/C's running day and night; 3 frigs, clothes washer and dryer which get used a lot (dryer pulls around 25 amps), two shower water heaters (normally only 1 is use at any one time), microwave, etc. I've had all 7 A/C's running, 3 frigs, TVs, and lights running as a test....pulled around around 65 amps according to my clamp-on amp meter. Lights did not dim....voltage level remained steady based on my voltmeter readings...but there is a transformer approx 50 meters away supplying power to my group of houses. I've run a few other tests with the clothes dryer and washing machine running, several A/C's on, and the other normal household items that would be on (i.e., frigs, lights, TVs, etc) to simulate what my maximun normal amp draw would be, and have never pulled more than 65 amps. Usually I'm pulling in the 10 to 20 amps range. I have a 80 amp main circuit breaker in the 100A service panel. I expect if I had every possible thing turned on in my house (which would include the clothes dryer and two water heaters which pull a bunch of amps) I expect I would pop my 80 amp main panel circuit breaker...maybe if I put in a 100 amp breaker it wouldn't pop but as mentioned I've never reached the 80 amp point yet....but I find the chances of me having every possible thing turned on as remote.

I think that "as long as you have a solid supply feeding your house," then a 30/100A single phase service is more than good enough unless you turned on all at once a bunch of high amp items like a clother dryer, water heaters, several large split-air A/C's, microwave (can pull around 10amps) plus the normal/always running frigs, lights, probably TVs, and other low amps things plugged in. I initially had concerns that a 30/100A service might not provide enough power, but after my tests and two years living in the house, those concerns are all gone.

If you have concerns about the first number in the service/meter rating (i.e., 30 of a 100amp meter), that first number only stands for the manufacturer's "test" amperage/rating for correct amps metering/measurement....this doesn't mean it won't measure accurately even at 100 amps, it just means 30amps is the "test" amps and is probably pretty close to the maximun most residences would be drawing frequently throughout the day.

**But don't forget, a LOT depends on the local service feeding your home as mentioned in an earlier post.*** If your local service/lines load down easily, then it don't matter if you got a thousand amp service in the house as your lights are going to dim when you turn on your A/C's, clothes dryer, etc.

Cheers and good luck in building the new house.

[longball53098]

If you have concerns about the first number in the service/meter rating (i.e., 30 of a 100amp meter), that first number only stands for the manufacturer's "test" amperage/rating for correct amps metering/measurement....this doesn't mean it won't measure accurately even at 100 amps, it just means 30amps is the "test" amps and is probably pretty close to the maximun most residences would be drawing frequently throughout the day.

Can you provide a source for this information? I am interested to learn more about the meters here.

[Pib]

If you have concerns about the first number in the service/meter rating (i.e., 30 of a 100amp meter), that first number only stands for the manufacturer's "test" amperage/rating for correct amps metering/measurement....this doesn't mean it won't measure accurately even at 100 amps, it just means 30amps is the "test" amps and is probably pretty close to the maximum most residences would be drawing frequently throughout the day.

Can you provide a source for this information? I am interested to learn more about the meters here.

I can't really remember now. I also got interested when I was doing my evaluation of my home electrical system. I found the info at several web sites from googling. I do remember one of the web sites was a contract document on the Metropolitan Electricity Authority (MEA) who provide the power in the Bangkok area. The document was a contract solicitation announcement and the associated requirements document identified the required specs of the meter they want to buy (thousands of them).

I just did another google just know and this California govt link came up high on the google list and it talks in detail about testing an electric meter for accuracy. http://www.cdfa.ca.g...vices/EPO39.pdf The following link also came up high on the list when I googled with some different words and seems to give a good overview: http://korrekt.com/energy/watt_hour_power_meter/Physics222Project.pdf

Cheers.

Edited June 25, 2010 by Pib

[katabeachbum]

I've had 30/100 service with 4 A/C units and, most times, if I turn them all on, the voltage drops, the lights dim, etc. That's single phase service. So, I suppose it depends on what your local supply can supply. Obviously, 3-phase could help, but I wouldn't want to pay for it.

I have 30/100 Amp single phase in some of my properties

With 35mm2 coppercables 60 meters to transformer, Voltage drops only approx 5 Volt when loaded approx 100 Amp.

Load is 7-10 13BTU aircons, poolpump0,75kwh, waterpumps1,5 kw, washingmachine2kw, dishwasher2kw, kitchenappliances10kw, hotwatertank2,2 kw, lights/spotlights4kw, TVs, fridges, etc.