Why Your MCB Keeps Tripping (Delhi Homes, 2026) — and What the Fix Costs

Diagnose it by WHEN it trips

This is the split that actually matters, and it is the one most articles skip. Three very different faults produce "the MCB keeps tripping", and the timing tells them apart.

Notice that in only one of those five rows is a new MCB even part of the answer.

The Delhi cause everybody misses: summer voltage sag

This is the one that costs people money for nothing, and almost no article names it.

On a 45°C afternoon in May, every AC in your colony is running at once, the local network is loaded, and the voltage reaching your flat sags. Here is the physics that matters: an AC compressor is a motor, and a motor asked to do the same work at a lower voltage draws more current to compensate. Add the normal start-up surge of a compressor kicking in, and the spike on that circuit is well beyond what it is on a mild March morning. So the MCB trips — only when the AC starts, only in peak summer, only in the afternoon.

Then comes the expensive part. The MCB gets blamed. It is replaced. It trips again next week, because nothing about the actual problem changed. The MCB was fine; it was reporting a real current spike, accurately.

The real fix is usually one of these:

• A voltage stabiliser for the AC. If your supply sags badly in summer, a stabiliser is the correct answer — and it protects the compressor, which is by far the most expensive part of your AC. People spend on a new MCB and skip the stabiliser, which is exactly backwards.
• A dedicated circuit for the AC. An AC sharing a circuit with a geyser or a kitchen is asking for a trip every time both come on. High-load appliances deserve their own line back to the board.
• A correctly rated MCB — not a bigger one. If the circuit was genuinely underspecified for the appliance now on it, then the wiring and the MCB both need to be right. That is an electrician's assessment, not a shop counter's.

How to spot it yourself: watch your lights. If they dim noticeably when the AC or the fridge kicks in, and if it is worse in the afternoon than at midnight, your supply is sagging. That is a voltage problem wearing an MCB costume.

The safe isolation test — find the culprit in ten minutes

No tools, nothing live touched. It is where an electrician would start anyway, and doing it before you call saves you their fault-finding time.

• 1. Switch off and unplug everything on that circuit. Every appliance, every charger — and switch the wall sockets off too, not just the appliances.
• 2. Reset the MCB, once. If it holds with nothing connected, the wiring is probably fine and an appliance is your problem. If it trips again immediately with the circuit empty, stop — the fault is in the wiring or the board. Leave it off and call an electrician.
• 3. Add things back one at a time, giving each a couple of minutes. An overload does not always announce itself in the first second.
• 4. The one that trips it is your suspect — commonly a geyser with a failing element, an old fridge, an iron, a water motor, or a cheap extension board that has been quietly cooking.
• 5. If nothing trips it alone but the circuit trips with several things on, that is an overload, not a fault. The honest fix is to split the load, not to fit a bigger breaker.

Write down what you found. "It trips within a minute of the geyser going on, nothing else does it" is worth more to an electrician than an hour of poking around — and it should show up as a shorter bill.

What you must never do

Three things. Each turns a safe warning into a real danger.

• Never tape, wedge or force an MCB into the ON position. It is the electrical equivalent of taping over a smoke alarm because the beeping is annoying. The breaker is cutting a current your wiring cannot carry; hold it closed and the wire heats up inside the wall, where you cannot see it, until the insulation gives up.
• Never fit a higher-rated MCB to "stop the tripping". The most common and most dangerous piece of bad advice in Indian homes. Swapping a 16A MCB for a 32A one does not fix the overload — it removes the protection. The rating is matched to what the wire can safely carry, not to what your appliances would like to draw, and a 16A wire carrying 30A is a wire cooking inside a wall. Fires start exactly here. If an electrician suggests this without also upgrading the wiring, find another electrician.
• Never keep resetting an MCB that trips instantly. Each reset re-energises a short circuit. Two attempts, fine. Hammering it back on repeatedly is how you get an arc, a burnt board and a very bad evening.

And one thing to always do: if you smell burning plastic, or see brown or black scorching around a socket, switchboard or the MCB itself — switch that circuit off and leave it off. That smell is insulation melting, and it is not a "get to it next week" problem. If the wiring throughout the flat is old, read the signs your house wiring needs replacing: repeated tripping is one of them.

What the fix typically costs in Delhi NCR

Nobody publishes this, which is odd, because it is the question you actually have. These are the ranges independent electricians across Delhi NCR generally quote in 2026, for labour. The MCB, the board and the wire are parts, and they are billed on top.

Indicative Delhi NCR market ranges, 2026. Each professional sets their own charge and quotes you free before starting. Parts are normally billed on top of labour.

When to stop and call an electrician

Call someone — today, not next week — if any of these is true:

• The MCB trips instantly on reset, even with the whole circuit unplugged.
• There is a burning-plastic smell, anywhere near the board, a switch or a socket.
• You can see scorching, soot or browning around a socket, a switchplate or the MCB.
• The board, a switchplate or a plug is warm or hot to the touch.
• The main MCB or the RCCB/ELCB is tripping, not just one circuit — that is an earth-leakage warning and it is protecting a person, not a wire.
• You get a tingle from a tap, a geyser body or an appliance casing. Stop using it immediately. That is current finding earth through you.

For everything else, the isolation test above will usually tell you which appliance is at fault, and you can arrive at the conversation informed. If you want the full labour picture before you call, our electrician charges guide for Delhi NCR lists the going rate for every common job — so you can tell a fair quote from a bad one before you agree to anything.