Tamil Nadu industrial electricity tariff: HT-I and LT-IIIB.

Who this page covers

Tamil Nadu has one state-owned distribution company, TNPDCL (Tamil Nadu Power Distribution Corporation Ltd., formerly TANGEDCO). TNERC sets its tariff for the whole state.

• HT-I: industries, factories and IT services on high-tension supply. The same tariff applies to consumers supplied at EHT. Demand is billed in kVA and energy in kWh.
• LT-IIIB: industries and IT services on low-tension supply that are not cottage, micro or power loom units.
• HT-III: commercial and other miscellaneous HT connections.

The rates below have applied since 1 July 2025. The order provides for a yearly inflation adjustment from 1 July, capped at 6%. As of 30 October 2026, no tariff order for 2026-27 appears on TNERC’s list of tariff orders, so the 2025-26 rates are shown.

HT rates

Unlike Uttar Pradesh, there is no lower rate for higher supply voltage, and energy is billed in kWh, not kVAh. A consumer who asks for a Green Energy Consumption certificate pays 110% of the category tariff.

Peak hours and the night rebate

Tamil Nadu has one set of hours for the whole year. It changes the energy charge only, not the demand charge.

This applies to all HT consumers except lift irrigation, temporary supply and EV charging stations. The 25% peak surcharge is fixed for FY 2022-23 to FY 2026-27. A unit moved from the peak into the night costs ₹2.25 less. The TOD tariff guide covers which loads can move.

Billing demand and excess demand

• Billing demand is the higher of the kVA demand actually recorded in the month and 90% of the contracted demand. Maximum demand is measured over 15-minute intervals. A 400 kVA contract pays for at least 360 kVA every month.
• Above sanctioned demand, the demand charge is based on the recorded kVA, and the exceeded demand alone is charged at double the normal rate (Supply Code Regulation 5(2)). For HT-I every excess kVA costs ₹1,216 in that month, against ₹608 below the sanctioned demand.

At 90%, Tamil Nadu’s floor is one of the highest in India, so an oversized contract demand costs money every month. The contract demand guide shows how to size it.

Power factor compensation

Because energy is billed in kWh, low power factor does not raise your units. It is charged as compensation instead. HT consumers must keep average power factor at 0.90 or more.

At 0.87 the charge is 3% of the current consumption charges; at 0.84 it is 9%. LT-IIIB and LT-V three-phase services must keep power factor at 0.85 or more: 1% per 0.01 down to 0.75, then 1.5%. See the power factor penalty guide and how to improve power factor.

LT-IIIB rates for smaller industries

Fixed charges are on contracted demand. LT-IIIB has the same 25% peak surcharge and 5% night rebate as HT. Until a ToD meter is fitted, the peak surcharge may be collected on 20% of total consumption, and the consumer can ask TNPDCL to fit one within 15 days. Welding sets are charged 15% extra. For industries up to 50 kW, the Government of Tamil Nadu chose to absorb the July 2025 increase, so your bill may show the earlier ₹81 and ₹8.00; check your latest bill.

LT excess demand is charged as a percentage of the total bill for every kW above the sanctioned demand (1% to 3%, rising with the occurrence), and on the third occurrence in 12 months the sanctioned demand is revised up to the recorded demand. Above 150 kW, a third occurrence is charged at 10% until the service moves to HT.

Worked example: a 400 kVA HT-I plant

An illustrative HT-I plant with a contracted demand of 400 kVA. In one month its maximum demand is 380 kVA and it uses 1,20,000 kWh: 30,000 in peak hours and 25,000 between 10 pm and 5 am.

Illustrative figures from TNERC Tariff Order No. 6 of 2025, assuming average power factor of 0.90 or more. TNPDCL may apply rounding in its own way; check against your bill. Work out your own HT-I or LT-IIIB bill with the electricity bill calculator.

In a slow month, the same plant pays for at least 360 kVA. If maximum demand falls to 300 kVA, it still pays ₹2,18,880 in demand charge: ₹36,480 for 60 kVA it did not use.

What one demand spike costs on HT-I

Suppose the same plant has one bad 15 minutes, say several heavy motors restarting together after a power cut, and maximum demand reaches 430 kVA. That is 30 kVA above the sanctioned demand. The plant pays ₹608 on 400 kVA (₹2,43,200) plus double rate on the 30 kVA excess (₹36,480). The demand charge goes from ₹2,31,040 to ₹2,79,680: ₹48,640 more, for one interval. The MD penalty guide explains how to stop it.

Where Tamil Nadu plants usually save

• Keep maximum demand below sanctioned demand. Above it, each kVA costs twice the normal rate, and with 15-minute integration a short spike is enough.
• Move flexible load out of the two peak windows. Eight hours a day carry 25% extra; the night window from 10 pm to 5 am carries 5% less.
• Hold average power factor at 0.90 or more. Every 0.01 below it adds at least 1% to the consumption charges.
• Check contract demand once a year. With a 90% floor, a contract demand set well above real maximum demand is paid for every month.

How KONDUKTOR® EMS helps

KONDUKTOR® EMS reads the multifunction meters already on your panels and shows, while the month is still running, the numbers this tariff bills you on.

• Running maximum demand against contract demand, with a warning as it approaches.
• Power factor for each meter, so a drop below 0.90 is caught the same day.
• Hourly energy, so you can see how much falls in the 6-10 am and 6-10 pm peak windows.
• Twelve months of maximum demand history to size contract demand.