Voltage Fluctuation in Delhi: What Needs a Stabiliser and What Does Not

1. What genuinely needs a stabiliser

The pattern is simple: things with a big motor, and things that are expensive to repair.

• The air conditioner, first and most important. A compressor asked to work at low voltage draws more current and runs hot, and the compressor is by far the costliest part of an AC. In a Delhi summer this is the one protection that repays itself. Many newer inverter ACs claim a wide operating range, but check the manual for your specific model rather than assuming.
• The refrigerator, especially an older direct-cool or non-inverter model. Same reason: a compressor, running all day, all year.
• A large television, if it is old enough to lack a wide-range internal supply. Newer sets usually do not need one.
• A water motor or pump, which is a motor doing hard work, often in an exposed location.
• The microwave or a heavy kitchen appliance in an area with genuinely bad supply, where the electronics have already failed once.

Buy a stabiliser sized for the appliance and matched to how far your supply actually swings. An electrician can measure your voltage at the worst time of day, which is the only sensible basis for choosing.

2. What does not need one

Money spent here is money not spent on the AC.

• Phone and laptop chargers. They already accept a very wide voltage range by design. A stabiliser adds nothing.
• LED bulbs, panels and most modern lighting. Their drivers handle normal swings. If your LEDs flicker badly, the cause is usually a cheap driver, a dimmer, or a loose connection rather than a need for a stabiliser — see why lights flicker.
• BLDC fans and most modern electronics that state a wide operating voltage range on the box. Check the range; if it comfortably covers your local swing, leave it alone.
• Anything already fed from an inverter or a UPS that regulates its output. Adding a stabiliser in front of a device that is already being protected is common and pointless.
• Small kitchen appliances such as a mixer or a toaster. They are simple, cheap to replace and not worth a stabiliser each.

One thing to know: a stabiliser corrects the voltage level. It is not a surge protector and it does not deal with a lightning strike. For sensitive electronics, a separate surge protection device is a different product and a different conversation with your electrician.

3. Know your own supply pattern

Fluctuation has a shape, and knowing yours tells you how much protection is justified.

• Summer afternoons and early evenings sag. Peak AC load across the colony. Lights dim, fans slow, the fridge sounds strained, and an inverter may refuse to charge until the voltage recovers.
• The moment power returns after a cut can spike. This is when appliances most often die. If cuts are frequent where you live, switch off the AC, the TV and the computer during a long outage and turn them back on a few minutes after supply returns.
• Storms bring surges. A pre-monsoon Delhi thunderstorm is a good moment to unplug what you can, especially anything connected to a set-top box or a broadband line.
• Winter evenings sag too. Heaters and geysers across the building during smog season do to the network what ACs do in June.
• Ask a neighbour. If their lights dip when yours do, it is the incoming supply. If only yours dip, the problem is inside your flat and no stabiliser will fix it.

4. When it is not fluctuation at all

Some very common symptoms get blamed on the supply and are actually a fault on your side of the meter. These do not need a stabiliser, they need an electrician.

• Lights in one room dim when something in another room switches on, or some lights brighten while others dim. That is a loose neutral, and it is a heat and fire risk, not a supply issue.
• A warm switchplate, socket or plug, or any smell of hot plastic. Switch that circuit off and call someone.
• Only one room fluctuates. Supply problems affect the whole flat and usually the whole building.
• A breaker trips whenever the AC starts. Read why an MCB keeps tripping first, because a stabiliser is sometimes the answer here and sometimes a distraction from an overloaded circuit.
• Old aluminium wiring in a flat now running ACs. Wiring designed for fans and lights is being asked to carry loads nobody imagined. See the signs house wiring needs replacing.

If you are planning protection for the whole flat rather than appliance by appliance, that is a distribution board conversation — see what a distribution board upgrade involves and the upgrades worth doing.