Electricity Meter Sizes in Thailand: How to Pick the Right One
ทีม TalataElectronics
Homes in Thailand run on four main single-phase meter sizes: 5(15), 15(45), 30(100) and 50(150) amps, and most ordinary houses sit on 15(45). The two numbers on the meter tell you its normal current and its short-term maximum. If you are house-hunting or renting, the meter size is worth a look, because it tells you straight away whether the electrical supply can handle your appliances. On Talata, where listings from many owners sit in one place, you can compare that kind of detail before you contact anyone.
What an electricity meter is and what the numbers mean
An electricity meter, or kWh meter, records how much power your home draws, measured in kilowatt-hours (the “units” on your bill). The utility reads this meter to calculate each month's charge. Its size also sets a ceiling: how much current your home can pull before the system trips.
Look at the rating on the meter face and you will see a figure like 5(15) or 15(45). The first number is the normal continuous current the meter is rated for. The number in brackets is the peak it can handle for short bursts. So a 5(15) meter runs at 5 amps normally and can spike to 15 amps when several appliances kick in at once. Draw more than that too often and the breaker cuts the supply to keep things safe.
Amps versus phases
Amps (amperes) measure how much current flows, so the more power-hungry appliances you run, the higher the amperage you need. “Phase” is something else: it describes how power is delivered to the property. Ordinary homes use single-phase supply at 220 volts. Three-phase supply (380 volts) shows up in very large houses or buildings with heavy electrical loads. Two different things, but you weigh both when you pick a meter.
Electricity meter sizes in Thailand
The utility offers meters in two groups by supply type: single-phase for homes, and three-phase for heavy loads.
Single-phase meter sizes
This is the group most homes use, chosen by how much power you draw.
5(15) amps handles real-world use up to about 10 amps. It suits rental rooms, dorms, or small houses with only a few appliances.
15(45) amps handles roughly 11 to 30 amps. Most detached houses, townhouses and condos use this size. If you are unsure which to pick, it is the safe starting point for a typical home.
30(100) amps handles roughly 31 to 75 amps. It fits larger houses with several air conditioners, multiple water heaters, or plans to add a home EV charger.
50(150) amps handles roughly 76 to 100 amps, used for very large homes or small office buildings.
Three-phase meter sizes
When the total load outgrows what single-phase can carry, you move to three-phase, which runs from 15(45), 30(100) and 50(150) up to 200 and 400 amps. The 200 and 400 sizes cover 101 to 200 and 201 to 400 amps. You see these in large homes with many air conditioners, big pumps or motors, or properties that double as a business.
Meter size at a glance
| Meter (single-phase) | Handles roughly | Best for |
|---|---|---|
| 5(15) | up to 10 amps | rental rooms, dorms, small homes |
| 15(45) | 11 to 30 amps | houses, townhouses, condos (most common) |
| 30(100) | 31 to 75 amps | large homes, several ACs, EV charging |
| 50(150) | 76 to 100 amps | very large homes, small offices |
The 5(15), 15(45) and 30(100) ranges match the Metropolitan Electricity Authority (MEA) guidance. Confirm the 50(150) and three-phase figures with MEA or the Provincial Electricity Authority (PEA) for your area, since details can change.
Single-phase versus three-phase: which to choose
The core difference is voltage and how much power can be delivered. Single-phase arrives at 220 volts and covers nearly every home. Three-phase arrives at 380 volts and is built to carry heavy loads and balance them better when several high-draw appliances run together.
People often assume a big house automatically needs three-phase. In practice, even a large home with many rooms runs fine on single-phase 15(45) or 30(100). You only step up to three-phase once the combined load genuinely exceeds what single-phase can carry, say more than ten air conditioners, a large pump or motor, or a home that also runs a business. Below that point, three-phase costs more than it is worth, both to install and to equip.
What size does your home need? Calculate it yourself
The most direct method is to add up the wattage of every appliance and convert it to amps. Take each device's power in watts, divide by 220 volts to get its current in amps, add them all together, then multiply by 1.25 to leave headroom for future use.
A worked example
Say a house has one 1,200-watt air conditioner: 1,200 divided by 220 is about 5.5 amps. Add lights, a TV, a fridge, fans and the usual small appliances for another 3 to 4 amps, and you reach roughly 9 amps. Multiply by 1.25 for headroom and you land near 11 amps, which falls inside the 15(45) range on the table above. That is why most homes settle on this size.
If your total lands close to the ceiling of a smaller meter, step up a size. Leaving headroom is far cheaper than changing the meter later.
Headroom for an extra AC or an EV charger
The common mistake is forgetting the heavy item you are about to buy. A home EV charger draws a lot, continuously, often 16 to 32 amps for an hour or more. If your home is on 5(15) or 15(45) and already near its ceiling, plugging in to charge while the AC runs can trip the supply. In that case, recalculate the whole-house load and move up to 30(100), or talk to an electrician before installing. The same goes for adding several air conditioners or a high-power water heater.
Meter sizes by property type
The right size does not depend only on how big the property is, but on how it uses power.
Detached houses and townhouses
Most land on 15(45). For a house with air conditioning in nearly every room, several water heaters, or a full electric kitchen, consider 30(100) from the start so you do not have to change it later.
Dorms, rental rooms and apartments
The renter's view and the landlord's view differ here. Renters often find the per-unit electricity cost in a dorm higher than at a house. That is not down to the meter size: it is because the owner sets their own rate, or uses sub-meters per room and adds a service charge on top. Before signing, ask exactly what the rate per unit is and check the actual sub-meter for that room.
For landlords setting up a dorm or a multi-room rental, fitting a sub-meter per room makes billing accurate and cuts disputes with tenants. The building's main meter should be sized to carry the combined load of all rooms when they draw power at once.
Condominiums
Most units come with a separate meter the developer already installed, usually 15(45). If you are buying a resale condo or renting, ask to see the meter size and recent bills to judge whether the supply suits how you use power.
Does a bigger meter mean a higher bill?
Many people assume that moving to a bigger meter pushes the bill up. It does not. The bill is calculated from the units (kWh) you actually consume, multiplied by the tariff for your user type, not from the meter size. A 30(100) and a 15(45) drawing the same power in a month cost the same.
Where meter size does differ is the one-off installation fee, which is higher for a bigger meter, and safety, since a larger meter carries more load without tripping. One more detail: residential users who consume no more than 150 units a month fall into a cheaper tariff band, but that condition is tied to consumption and user type, not to the meter size.
How to change your electricity meter size
When your calculation shows the existing meter is too small, or the supply trips whenever appliances run together, that is the signal to change it. You apply to the utility for your area. In Bangkok, Nonthaburi and Samut Prakan, contact the Metropolitan Electricity Authority (MEA) on 1130. Elsewhere, contact the Provincial Electricity Authority (PEA) on 1129.
Documents and steps
The main documents are usually a copy of the house registration for the property, a copy of your ID, and proof of your right to the premises, such as a sale or rental contract. An officer checks that the internal wiring can support the new meter size before installation. In some cases the main line and breaker have to be upgraded to match the meter, which is work an accredited electrician should handle for safety.
Rough costs
Fees for changing or installing a meter vary widely by size, from a few hundred baht for 5(15) up to the tens of thousands for 30(100) or three-phase, plus wiring and parts depending on the site. These figures change with utility announcements, so check the latest rate before you apply. The full breakdown of documents, fees and steps lives in our dedicated guide to applying for an electricity meter.
Finding a home with the right electrical setup on Talata
When you are looking for a house, condo or rental room, the meter size is a small detail that affects daily life. A home whose meter matches its use saves you from paying to upgrade later. On Talata, where property listings from many owners sit in one place, you can compare location and price and ask the owner about the electrical supply directly before deciding.
If you are renting out a house or dorm, stating the meter size and electrical setup in your listing helps tenants decide and makes the listing more credible. Start by searching or posting a home or rental on Talata, and when you find one whose supply matches how you live, get in touch.
Frequently Asked Questions
What size meter does a typical home need?
Most houses, townhouses and condos use a 15(45) single-phase meter, which handles roughly 11 to 30 amps, enough for air conditioning, a fridge, a washing machine and the usual appliances. Step up to 30(100) only if you run several air conditioners or multiple water heaters.
What is the difference between 5(15) and 15(45)?
It comes down to how much power they carry. A 5(15) handles real use up to about 10 amps, which suits a rental room or a small home with few appliances. A 15(45) handles roughly 11 to 30 amps and supports a home with air conditioning and a full set of appliances. Run more than a 5(15) can take and the supply trips often.
Do I need to change my meter for an extra AC or an EV charger?
It depends on whether the total load exceeds your meter's ceiling. A home EV charger draws a lot, continuously, so if you are on 5(15) or 15(45) and already near the limit, you will usually need to move up to 30(100). The safe route is to have an electrician assess the whole-house load before installing.
Does a bigger meter cost more per unit?
No, not on the per-unit rate. The bill is based on the units you use and your user type, not the meter size. A bigger meter only carries a higher one-off installation fee, in exchange for handling more load without tripping.
Where do I check my own meter size?
Look at the figure on the meter face outside the property, marked like 5(15), 15(45) or 30(100). If it is hard to read or you have a digital meter, check your electricity bill or ask your local electricity authority.
