The distinction is about supply voltage
Low tension means the DISCOM delivers power to you at utilisation voltage — nominally 230 volts single-phase or 400 volts three-phase. The distribution transformer that steps the voltage down belongs to the utility and is shared among consumers in your area. You connect your wiring and start using power.
High tension means you are supplied at a distribution voltage — commonly 11 kV, and at 33 kV or above for larger consumers — and you take responsibility for stepping it down. That means your own substation: transformer, switchgear, protection, earthing, and the statutory approvals and maintenance that come with owning it.
The short version
LT consumers buy electricity ready to use. HT consumers buy it at a higher voltage, cheaper per unit, and own the equipment that makes it usable.
Where the boundary falls
The boundary is set by load. Small loads are supplied at LT because it would be absurd to ask a household to run a substation. Large loads are supplied at HT because drawing that much current at 400 volts would overload the LT network and cause unacceptable losses and voltage drop.
In the current AP LT schedule, the industrial LT categories extend up to 150 kW, with the fixed charge stepping up sharply beyond 75 kW — from ₹75 to ₹275 per kW per month for the relevant categories. That escalation is a deliberate signal: as load grows, LT supply becomes progressively less attractive, and beyond the LT ceiling a consumer moves to HT at 11 kV. The exact threshold and conditions applicable to a specific connection are governed by the tariff order and the DISCOM’s supply conditions, so confirm them with your DISCOM before planning around a number.
Scope of this site
The calculator and tariff tables here cover LT categories only. HT tariffs involve demand charges, kVAh billing and power factor adjustments that need your recorded maximum demand and metering data, and are not estimated by this tool.
How the billing differs
This is where the practical difference shows up. An LT domestic or commercial bill is driven overwhelmingly by units consumed, with a modest load-based fixed charge. An HT bill has two components of comparable weight, and one of them does not depend on consumption at all.
| Aspect | LT supply | HT supply |
|---|---|---|
| Supply voltage | 230 V single-phase, 400 V three-phase | 11 kV and above |
| Step-down transformer | Owned and maintained by the DISCOM | Owned and maintained by the consumer |
| Energy charge basis | Mostly kWh, telescopic slabs or flat rates | Typically kVAh, generally a flat rate per unit |
| Capacity charge | Fixed charge on sanctioned or connected load in kW | Demand charge on contracted or recorded maximum demand in kVA |
| Power factor | Not usually billed on for small consumers | Penalised when poor, sometimes incentivised when good |
| Metering | Single or three-phase energy meter | Trivector or ABT-class meter recording demand, kVAh and time blocks |
| Per-unit cost | Higher, particularly in upper domestic and commercial slabs | Lower, offset by demand charges and self-owned infrastructure |
Demand charges and why they hurt
An HT consumer contracts for a maximum demand and is billed for it whether or not it is used. If your recorded demand exceeds the contracted figure, penal rates typically apply. So an HT consumer manages two things at once: total consumption, and the peak at which that consumption is drawn. A factory that runs every large motor simultaneously for ten minutes a month can pay for that peak all year. Staggering startups and controlling peaks is real money.
kVAh billing and power factor
HT energy charges are commonly levied on kVAh — apparent energy — rather than kWh. The difference between the two is your power factor, which reflects how much of the current you draw does useful work. Inductive loads such as motors degrade it. Billing on kVAh means a poor power factor directly inflates your bill, which is why HT consumers install capacitor banks: correcting power factor reduces billed units without reducing production. LT consumers, billed on kWh, generally see no such direct benefit.
Deciding between them
For a household, a shop or a small workshop there is no decision — LT is the only sensible option. The question becomes real for a growing commercial or industrial consumer approaching the LT ceiling. Points worth weighing:
- Load factor. HT rewards steady, high utilisation, because the demand charge is spread over more units. A high peak with low overall consumption is the worst case.
- Capital cost. A substation, switchgear and protection are a substantial upfront investment, plus space and statutory clearances.
- Operating responsibility. Transformer maintenance, testing and the risk of a failure becoming your outage all move to you.
- Reliability and voltage quality. HT consumers are often less exposed to LT network disturbances, which matters for sensitive equipment.
- Growth headroom. If your load will keep rising, migrating once is better than repeatedly straining an LT connection.
- Power factor. If your loads are heavily inductive, budget for correction equipment from the start rather than discovering it on a bill.
Run the arithmetic on your own numbers before committing. A consumer with a modest load factor can find that lower per-unit HT rates are wiped out by demand charges. Ask your DISCOM for the applicable HT schedule and model it against twelve months of your actual demand and consumption data, not against a typical month.
Frequently asked questions
Is HT electricity always cheaper?
The per-unit energy rate is lower, but HT bills add demand charges based on contracted demand and may be levied on kVAh, and you carry the capital and maintenance cost of your own substation. Whether it works out cheaper depends mainly on your load factor.
Does this calculator cover HT connections?
No. It covers LT categories from the APERC FY 2026-27 LT schedule. HT estimation needs contracted demand, recorded maximum demand, power factor and kVAh data, and is outside the scope of this tool.
What voltage is a normal home supplied at?
Indian domestic supply is nominally 230 volts single-phase. Larger homes with higher sanctioned load may take a three-phase LT connection at nominally 400 volts.
How do I know whether my connection is LT or HT?
Your bill states the category and supply voltage. If you do not own a step-down transformer and your meter is an ordinary single or three-phase energy meter, you are almost certainly an LT consumer.