Low voltage is a fault, not weak power

There is a particular kind of Indian evening that households have simply learned to live with. The fan turns, but slowly. The tubelight is on, but the room is the colour of a photocopy. The fridge clicks every few minutes and never quite gets cold. Nobody rings the discom, because technically the power is on.

It is not on in the sense that matters. Voltage is the pressure behind the current, and every appliance in the house was built for a particular pressure. A reading of 170 V on a 230 V connection is not “a little less power”. It is a fault in the supply, it has a number attached to it in your state's regulations, and it is doing measurable damage while you wait for it to pass.

What the number is supposed to be

In most of India a domestic connection is declared at 230 volts between phase and neutral, and 400 volts between phases where the supply is three-phase. This is not folklore — it is written into the supply code your discom operates under. Rajasthan's Electricity Supply Code, 2021 states it in clause 3.1: low-tension supply is 230 V single-phase, 400 V three-phase.

If you grew up being told the figure was 240, you were not misinformed. India began moving from 240/415 V to 230/400 V decades ago and never finished the job. When the Central Electricity Authority sat down with discoms and regulators in January 2022 to settle the question, it found five states — Sikkim, Kerala, Tamil Nadu, Telangana and Andhra Pradesh — still declaring 240 V, with Maharashtra recognising both. Twenty-three states and union territories were already on 230 V.

The tolerance is the more useful number, and it is the one most writing on this subject gets wrong. The familiar “±6%” came from Rule 54 of the Indian Electricity Rules, 1956 — and those rules were replaced in 2010 by the CEA's Safety and Electric Supply Regulations, which carry no consumer voltage-variation clause at all. The binding figure now sits with your state. At that 2022 meeting Maharashtra's regulator described permitting +10% / −15% at the point of supply, while Tamil Nadu's utility described +6% / −10%. The panel itself settled on 230 V ±10%, to be tightened to ±6% “in due course of time”.

Which gives you the bands to judge your own reading against.

What 170 volts actually does to a fridge

Start with the motors, because they are what break. An induction motor — the compressor in your refrigerator, the pump on the terrace, the motor in a cooler — produces turning force roughly in proportion to the square of the voltage it is given. At 170 V instead of 230 V you have about three-quarters of the voltage, and therefore only a little over half the torque.

A compressor with half its torque cannot always overcome the pressure of the refrigerant it is asked to push. So it does not turn. It sits there as a stalled motor — locked rotor, in the trade — drawing several times its rated current and converting all of it into heat in the windings. A few seconds later the thermal overload clicks it off. A few minutes later it tries again. That cycle, repeated across a summer, is what turns a ten-year compressor into a three-year compressor.

The electronics are quieter about it, and run the same arithmetic backwards. A television, a laptop charger, an inverter air conditioner and a modern BLDC fan all draw close to constant power: they take the watts they need whatever the voltage is. Power is voltage times current, so when voltage falls by a quarter, current rises by about a third to compensate. That extra current runs through your wiring, your switchboard joints, your meter, the service cable to the building and the transformer at the end of the lane — heating every one of them, because heating rises with the square of current.

The dim tubelight, in other words, is the least of it. It is simply the only symptom you can see.

How a street's low voltage becomes a street's blackout

Here is the part that surprises people. Low voltage is not merely a nuisance you endure until the cut arrives. It is frequently the mechanism of the cut.

Voltage falls along a low-tension line the further you sit from the distribution transformer, and it falls further as load rises. On a hot evening every house on the line switches on at once, so the far end sags. The appliances there respond by drawing more current, for the reason above. More current through the same cable means a bigger drop, which means lower voltage still, which means more current again. The loop reinforces itself, and it ends in one of three places: the transformer's low-voltage fuse blows, the feeder's overcurrent protection trips the line, or the transformer overheats and fails outright.

From your balcony all three look identical. The lights go out.

None of this is speculative. In the CEA's own minutes of that January 2022 meeting, Tamil Nadu's regulator objected that lowering the declared voltage would push consumers at the end of long rural lines down to 190 or 180 volts. Delhi's TPDDL noted that transformers of 250 kVA and below often have no tap changer at all, leaving the utility no way to correct voltage on the low side. Engineers call the large-scale version of this voltage collapse. In your lane it does not need to be large-scale — one overloaded 100 kVA transformer is enough.

It is worth being precise about the claim, because the internet is not. Low voltage in your house does not bring down the state grid. What it does is take out the last transformer between the grid and you, which for the purposes of your evening is the same thing.

Reading your own supply

Not every low reading is the discom's fault, and the difference decides who you should be talking to.

Getting a number you can use

A complaint that says “voltage is low” invites the reply that it is not. A complaint with readings attached is a different conversation.

1. Buy a plug-in socket voltmeter. ₹200 to ₹400, goes into any socket, shows voltage continuously. Safer and more useful than probing live terminals with a multimeter, which we would not suggest anyone do.
2. Read the display you already own. Most stabilisers, inverters and many ACs show their input voltage. So does the panel or app on a home UPS.
3. Log it, don't remember it. Date, clock time, reading. A photograph with the time visible is better. Three evenings of readings is a case; one is an anecdote.
4. Write down what else was true. How hot it was, whether the whole lane was dim, whether it cleared by midnight, and what was running in your own house at the time.

Then put it somewhere it does some work. A report on the live map answers the first question your discom will ask — is it only your house, or the whole area — and that is the one question you cannot answer on your own.

What your discom owes you for it

Low voltage is not a favour you are requesting. Your state's standards of performance give the discom a deadline to fix a voltage complaint and, in many states, a sum it pays when it misses. Rajasthan's schedule pays ₹150 for a voltage problem at a home connection and ₹450 on high tension. Kerala's, revised in March 2026, pays ₹200 for every week a voltage problem is left unfixed.

We keep the state-by-state amounts, deadlines and the claim procedure on one page: power cut compensation in India.

A burnt appliance is a separate matter and a separate claim, usually in consumer court. The compensation above is for the unfixed voltage problem, not for the fridge. Keep the purchase bill and the repair receipt — without them the claim is hard to run.

Questions people actually ask