If you are on a TOU tariff, every cell for categories 3, 4 and 5 is identical, and the energy charge of the non-TOU rows is also the same across all categories. Only two things genuinely differ. First, the demand charge in the non-TOU rows (category 3 normal rate is a single value, category 4 TOD splits it by period of the day, category 5 without a TOU meter yet is another value). Second, the rate types available: the normal rate and TOD are open only to existing customers, while new customers go onto TOU.
Every rate figure in this article is the base rate from the business tariff announcement of PEA (Provincial Electricity Authority) for the September 2026 billing period, covering the high, medium and low voltage levels. Ft is announced separately and sits outside this table (What is Ft? (in Thai)).
| Category | Main rate type (new customers go here) | Other rate type | Who may use the other type |
|---|---|---|---|
| Category 3 (medium business) | TOU (3.2) | Normal rate (3.1) | Existing customers only |
| Category 4 (large business) | TOU (4.2) | TOD (4.1) | Existing customers only |
| Category 5 (hotels / residential rental) | TOU | Rate for customers without a TOU meter yet | Temporary, until a TOU meter is installed |
Where do categories 3, 4 and 5 differ, and where are they the same?
All three categories use the same set of energy charges in the same kind of row. What differs is the demand charge in the non-TOU rows and the rate types each category can choose from.
Before comparing tables, a one-sentence recap of the categories: category 3 is medium business, category 4 is large business (the demand and consumption thresholds for these two categories are in the article How much does factory electricity cost per unit?), and category 5 is hotels or residential rental businesses.
Once you know your category, the next question is how many tables your category has. Category 3 has two: the normal rate (3.1) and TOU (3.2). Category 4 has two: TOD (4.1) and TOU (4.2). Category 5 has one, TOU, which applies to every category 5 customer; those who have not yet installed a TOU meter are billed temporarily at a non-TOU rate until the meter is installed.
But not everyone can choose between both. The normal rate (3.1) and TOD (4.1) are reserved for existing customers: PEA customers who were on this rate before the Nov 2015 bill, and MEA (Metropolitan Electricity Authority) customers who were taking supply before Oct 2000. New customers in every category go onto TOU. Existing customers who want to move from the normal rate or TOD to TOU may do so, but cannot move back, and the move carries cost conditions that must be settled first.
The part that confuses most people when they open the table is that the figures all look the same. That is because the energy charge (the money billed by number of units used) in the same kind of row is identical across every category, and if you are on TOU, both the energy charge and the demand charge are one and the same set of figures for categories 3, 4 and 5. Only two real differences remain. The first is the demand charge in the non-TOU rows: category 3 normal rate is a single value for the whole month, category 4 TOD splits it by period of the day, and category 5 without a TOU meter yet is another value. The second is the rate types available, as described above. The table in the next section lays all of this out in one place.
- Energy charge
- The part of the bill charged by the number of electricity units used in the billing month; the more units used, the more you pay.
- Demand charge
- The part of the bill charged by the highest power the factory draws from the grid in the billing month, priced per kilowatt and independent of how many units were used.
- TOU
- A rate type that prices the energy charge per unit differently by time of day, split into On Peak and Off Peak periods.
- TOD
- A rate type for large businesses that charges demand differently by period of the day (On Peak · Partial Peak · Off Peak), while the energy charge is a single price at all times.
Rate table for all three categories, every voltage level
Pick the row from your category and rate type, pick the column from the voltage level your utility has assigned you. The cell where they meet is your base rate.
This table places every rate type of categories 3, 4 and 5 together. The row tells you the category, the rate type, and whether it is an energy charge or a demand charge. The column tells you the voltage level. Using the table therefore takes two steps: find your own row first, then move across to your own voltage level column.
One thing to know about voltage levels: the kilovolt boundary that separates the medium voltage level from the low voltage level is not the same at PEA and MEA. Use the voltage level your own utility has assigned you and do not compare across utilities (details are in the article PEA vs MEA).
Before reading the demand charge rows, you need to know the base each one is measured on: the normal rate uses the highest value of the whole month, TOU uses only the highest value within the On Peak period, and TOD splits by its own periods (the full mechanism is in the article What is the demand charge and how is it calculated?). The per-kilowatt figures in the different rows are therefore not always multiplied by the same base.
| Item | High voltage level | Medium voltage level | Low voltage level |
|---|---|---|---|
| Category 3 normal rate (3.1) · Energy charge | 3.1097 THB/kWh | 3.1471 THB/kWh | 3.1751 THB/kWh |
| Category 3 normal rate (3.1) · Demand charge | 175.70 THB/kW | 196.26 THB/kW | 221.50 THB/kW |
| Category 3 TOU (3.2) · Energy charge On Peak | 4.1025 THB/kWh | 4.1839 THB/kWh | 4.3297 THB/kWh |
| Category 3 TOU (3.2) · Energy charge Off Peak | 2.5849 THB/kWh | 2.6037 THB/kWh | 2.6369 THB/kWh |
| Category 3 TOU (3.2) · Demand charge On Peak | 74.14 THB/kW | 132.93 THB/kW | 210.00 THB/kW |
| Category 4 TOD (4.1) · Energy charge, all periods | 3.1097 THB/kWh | 3.1471 THB/kWh | 3.1751 THB/kWh |
| Category 4 TOD (4.1) · Demand charge On Peak | 224.30 THB/kW | 285.05 THB/kW | 332.71 THB/kW |
| Category 4 TOD (4.1) · Demand charge Partial Peak | 29.91 THB/kW | 58.88 THB/kW | 68.22 THB/kW |
| Category 4 TOD (4.1) · Demand charge Off Peak | Not charged | Not charged | Not charged |
| Category 4 TOU (4.2) · Energy charge On Peak | 4.1025 THB/kWh | 4.1839 THB/kWh | 4.3297 THB/kWh |
| Category 4 TOU (4.2) · Energy charge Off Peak | 2.5849 THB/kWh | 2.6037 THB/kWh | 2.6369 THB/kWh |
| Category 4 TOU (4.2) · Demand charge On Peak | 74.14 THB/kW | 132.93 THB/kW | 210.00 THB/kW |
| Category 5 TOU · Energy charge On Peak | 4.1025 THB/kWh | 4.1839 THB/kWh | 4.3297 THB/kWh |
| Category 5 TOU · Energy charge Off Peak | 2.5849 THB/kWh | 2.6037 THB/kWh | 2.6369 THB/kWh |
| Category 5 TOU · Demand charge On Peak | 74.14 THB/kW | 132.93 THB/kW | 210.00 THB/kW |
| Category 5 without TOU meter yet · Energy charge | 3.1097 THB/kWh | 3.1471 THB/kWh | 3.1751 THB/kWh |
| Category 5 without TOU meter yet · Demand charge | 220.56 THB/kW | 256.07 THB/kW | 276.64 THB/kW |
Run your eye down a single column and the table says it itself: the TOU rows of category 3 (3.2), category 4 (4.2) and category 5 TOU are the same set of figures at every voltage level, for the On Peak energy charge, the Off Peak energy charge and the On Peak demand charge alike. This means that if your factory or hotel is on TOU, whatever the category, you open the same row and the figures do not change with the category.
The energy charge of the non-TOU rows is also equal across categories: the category 3 normal rate, the all-periods energy charge of category 4 TOD, and the energy charge of category 5 without a TOU meter yet are the same figure at the same voltage level. The real difference is therefore confined to the demand charge rows of the non-TOU rates: category 3 normal rate is a single value, category 4 TOD splits into On Peak and Partial Peak with no charge in Off Peak, and category 5 without a TOU meter yet has a value of its own. If you sit in one of the rows in this group, you must get your own category right before reading the figures.
Every cell is the base rate for that row. It does not yet include the case where PEA adds an amount when the meter is installed on the low-voltage side of the customer's own transformer, which is covered in the article How much does factory electricity cost per unit?.
Notice that the category 5 rows in this table carry no sub-code. That is deliberate, because PEA and MEA use the numbers the other way round: PEA's announcement makes 5.1 the TOU rate and 5.2 the rate for customers without a TOU meter yet, while MEA's makes 5.2 the TOU rate and 5.1 the rate without a TOU meter yet, even though every rate figure is identical. If you manage hotels or residential rental businesses with sites in both areas, compare by rate type (TOU or without a TOU meter yet), not by code number. Even PEA's own website calculator uses the numbers the other way round from PEA's announcement.
✗ Codes 5.1 and 5.2 mean the same rate type whether they come from PEA or MEA.
✓ The numbers are swapped: PEA uses 5.1 = TOU and 5.2 = without a TOU meter yet, while MEA uses 5.2 = TOU and 5.1 = without a TOU meter yet. Every rate figure is identical, so compare by rate type, not by code number.
How does category 4 TOD differ from TOU?
TOD charges energy at a single price all day but charges demand differently by period of the day. TOU is the other way round: two energy prices by time period.
From the table you can see that TOD (4.1) is the row that looks like no other. The energy charge is a single price used in every period, but the demand charge splits into On Peak and Partial Peak and is not charged in Off Peak. This is what sets TOD apart from TOU: it is not about a per-unit price that changes with the time, but about whether the highest power you draw in a given part of the day is billed or not.
The TOD clock is the same every day, with no distinction for holidays: the On Peak period runs from 18.30 to 21.30, and demand is charged on the highest value in this period. The Partial Peak period runs from 08.00 to 18.30, and demand is charged only on the portion above the On Peak value. The remaining Off Peak period, from 21.30 to 08.00, carries no demand charge at all.
In practice, for anyone on TOD, the two demand charge rows in the table are not always billed at the same time. The Partial Peak row only takes effect when your highest daytime power exceeds your highest On Peak power. And if the factory runs heavy loads only during the hours that fall in Off Peak, the highest power in that period is not billed as a demand charge.
TOU has its own On Peak and Off Peak periods, which are not the same clock as TOD, and working days and holidays come into play. See the periods in the article What hours are TOU On-Peak / Off-Peak?.
TOU is like a fare that goes up in the rush hour and comes down at other times: the price per unit changes with the time. TOD is like a space booking where the price per unit stays the same throughout, but the booking fee for power is charged in full in one part of the day, charged only on the excess in another, and not charged at all for the rest.
TOD (category 4 · 4.1)
- Single energy price, used in every period
- Demand charge split by period: On Peak charged on the highest value in the period · Partial Peak charged only on the portion above the On Peak value · Off Peak not charged
- Same clock every day, no distinction for holidays
- Category 4 only, and existing customers only
TOU (3.2 · 4.2 · category 5)
- Two energy prices, split into On Peak and Off Peak
- Demand charge has a single On Peak row
- Periods distinguish working days from holidays (see the TOU article)
- Available in every category, and the type new customers go onto
When are you moved to another category, and can you move back?
Category 3 moves up to category 4 on reaching the large-business line, but category 4 does not come back down to category 3 even when usage falls.
The rule to know before expanding production capacity is the line upward. Category 3 is moved into category 4 (large business) when demand reaches 1,000 kW or more, or when consumption in units per month, averaged over three months, exceeds 250,000 kWh/month. MEA states clearly that the customer enters rate 4.2 from the month after the TOU meter is installed; at PEA it follows the category definition. This move is not something you request; it follows from your own usage figures. Knowing the line in advance lets you open the category 4 table beforehand and see how the demand charge rows will change shape.
The line downward is not symmetrical with the line upward. At PEA, in any month where a category 4 business has demand below the large-business line, or uses no more than the monthly unit ceiling, the bill continues to be charged at category 4 rates. There is no way back down to category 3. MEA's announcement does not state this point in so many words; it only has a clause on dropping to category 2.
The only way down is to category 2, when demand stays below the small-business threshold continuously for the period the announcement specifies, during which the existing rate still applies (conditions are in the article How much does factory electricity cost per unit?). So for a category 4 factory, cutting usage down to category 3 levels does not change the table you use; the demand charge row you need to open is still the category 4 row.