Why summer power cuts hit harder in Tamil Nadu

If you've lived through even two or three Chennai or Coimbatore summers, you already know the pattern: cuts that were rare in December start showing up weekly by May. It's not your imagination, and it's not random bad luck with your particular street.

Two loads stack on the same feeders at the same time of year. Domestic air conditioning use climbs hard from April through June — a single split AC can pull as much as five or six ceiling fans combined. At the same time, agricultural pump sets on the same rural and semi-rural feeders often run longer hours because groundwater levels have dropped and farmers are pumping more to compensate for low rainfall.

A distribution transformer is sized for an expected average load, not for everyone's AC running flat out in the same three-hour window. Push past that and the transformer's protection trips it before it overheats and fails outright — which is a good thing, since a burnt transformer takes far longer to replace than a tripped one takes to reset. Planned maintenance shutdowns also cluster in this window because it's the sensible time to reinforce a feeder before it starts failing on its own.

None of this makes an afternoon without power any less annoying. But it does explain why the same street that goes years without a scheduled cut suddenly appears on the list three times in May — and why cuts easing off in July, once the load and the weather both back off, isn't a coincidence either.

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What actually happens on the feeder

A distribution transformer is rated in kVA for a load that assumes people use appliances at different times. Summer breaks that assumption: air conditioners, fans, fridges working harder, and irrigation pumps all peak within the same afternoon and evening window. Once the transformer runs above its rating for a sustained period, its oil temperature climbs and its protection trips it, or a fuse operates. The alternative — letting it run hot — destroys a unit that takes hours or days to replace.

Why maintenance is scheduled in exactly this season

It looks perverse to plan shutdowns during the hottest months, but the alternatives are worse. Pre-monsoon is when tree branches near lines must be cleared before wind brings them down, when weak poles and worn insulators must be replaced before they fail in rain, and when feeders that are close to overload must be split or reinforced. A planned four-hour cut in May prevents an unplanned twelve-hour cut in November.

Reducing your own exposure

• Set the air conditioner to 26–27°C rather than 18°C. The compressor cycles far less and the room still cools; each degree costs roughly 5–6% more energy.
• Service the AC filter before summer — a clogged filter makes the compressor run longer for the same cooling.
• Run the washing machine, iron and water heater outside the 6 pm to 10 pm peak.
• Replace an old direct-cool fridge or a conventional ceiling fan; a BLDC fan uses roughly a third of the power of an old induction motor fan.
• Keep the inverter battery healthy before April rather than after the first bad cut.

None of this stops a planned shutdown, but a lower household peak means fewer of the short evening trips that come from a strained local transformer — and a visibly smaller bimonthly bill.