Which MCB for Home? The Right Rating for Each Circuit

Which MCB for home: the short answer

The MCB for home use is chosen per circuit. A miniature circuit breaker sits in the distribution board and switches a circuit off when too much current flows through it, either because of an overload (too many appliances on one line) or a short circuit (a fault). Its job is to trip before the wire behind it overheats.

That is why the rating follows the wire and the circuit. A lighting circuit wired for light loads typically gets a 6A or 10A MCB. A socket circuit typically gets 16A. A geyser, an AC or a kitchen appliance point is usually given its own circuit with its own MCB. The main line coming in from the meter gets a double pole MCB or isolator sized to your sanctioned load.

We manufacture MCBs, isolators and distribution boxes at our works in Marol, Andheri East, Mumbai, under our VIYONA range, from 6A to 63A and from single pole to four pole, all with a 10 kA breaking capacity. This guide tells you what each part of a home typically needs. What it cannot do is size your wiring: the cable, the load and the board layout are decided by a licensed electrician who has seen the house.

Which MCB rating does each circuit need?

Each home circuit typically needs the MCB that matches its cable and load: lights and fans take a 6A or 10A single pole MCB, general socket circuits 16A, a geyser its own 16A or 20A, each AC its own 16A to 25A by size, and the main line a double pole MCB or isolator of 32A to 63A.

In short: 6A and 10A protect light circuits, 16A protects socket circuits, 16A–20A a geyser, 16A–25A an AC and 32A–63A the incomer. Your electrician confirms each one against the cable actually laid.

Notice that the main line is not simply the sum of every MCB below it. Not every circuit runs at full load at once, so the incomer is sized to the sanctioned load on your electricity connection, not to the total of the ratings in the board.

What size MCB for a geyser?

A geyser typically gets its own 16A or 20A MCB on a circuit that feeds nothing else, because a 2,000 W storage geyser draws about 8.7 A and a 3,000 W one about 13 A at 230 V, for long stretches, and that steady load is exactly what overheats a shared socket circuit. The geyser’s manual states the breaker it expects.

Match the wall point to the MCB. On a 16A circuit the geyser can plug into a 16A socket such as our VIZA V263 16A socket (₹160), never a 6A socket, which its plug will not fit. On a 20A circuit it is usually wired to a DP switch such as the VIZA V1250 32A DP switch with indicator (₹330), so the indicator shows when the heater is live.

Which MCB for an AC?

An AC typically gets its own MCB sized to its tonnage: about 16A for a 1 ton unit, 16A or 20A for a 1.5 ton unit and 20A or 25A for a 2 ton unit, often double pole, with the breaker stated in the AC’s installation manual taking priority over any general figure, including ours.

1 ton: 16A 1.5 ton: 16A–20A 2 ton: 20A–25A One AC, one MCB. The compressor’s start-up surge and the long summer running hours are why an AC never shares a circuit with the room’s sockets.

Our guide to the MCB for 1, 1.5 and 2 ton AC goes through each size, inverter vs fixed-speed units, single vs double pole and the socket or switch that goes on the wall. The ratings there and here are the same, on purpose.

Which MCB for a switch board?

A switch board does not usually hold an MCB at all: the MCB for a switch board sits in the distribution board and protects the circuit that feeds it, typically 6A or 10A for a board with only lights and fans, and 16A for a board with sockets, unless a modular MCB is fitted in the board itself.

That modular option exists. Our KEMPS TinyTrip K225 is a single pole modular MCB from 10A to 32A at ₹295, and K226 is the double pole version at ₹625. They fit the switch board and let one point, such as a geyser or a heater, be cut locally. The range is on our TinyTrip modular MCB page.

A modular MCB on the board is an extra, not a replacement: the circuit still needs its MCB in the distribution board. For which switches and sockets go on the board, see 6A vs 16A socket and the switch and socket ratings table.

Which MCB for the main line?

The main line, the incomer from the meter into your distribution board, typically takes a double pole MCB or isolator of 32A, 40A or 63A, sized by your electrician to the sanctioned load and the incoming cable, because double pole breaks both phase and neutral and fully isolates the house when it is off.

A small flat with lights, fans and a couple of ACs commonly runs on a 32A or 40A incomer; a larger home with several ACs and geysers moves up to 63A. We make the 10 kA double pole MCB in 6–32A, 40A and 63A, and a 40A and 63A isolator for boards where the incomer only needs to switch, not trip.

MCB vs isolator: which does the main switch need?

The main switch needs an MCB when it must also protect the cable from the meter, and it can be an isolator when every circuit below it already has its own MCB, because an MCB switches and trips on overload or short circuit, while an isolator is only a heavy-duty on/off with no tripping mechanism at all.

An MCB switches and trips. An isolator only switches. Both look similar in a board, which is why they get confused. Our isolators come in double pole 40A and 63A, three pole 40A ₹370 and 63A ₹400, and four pole 40A ₹480 and 63A ₹530.

An isolator makes sense as the main switch when the protection is already there and the incomer simply needs to cut the whole board for maintenance. Your electrician decides which, based on how the board is laid out.

For the full comparison, including where an RCCB fits and how to tell the two apart in a board, see isolator vs MCB.

Single pole or double pole MCB?

Use a single pole MCB for ordinary home circuits such as lights, sockets and a geyser point, because it breaks the phase only, and a double pole MCB for the main incomer and often for heavy dedicated circuits such as an AC, because it breaks phase and neutral together and leaves the circuit fully isolated.

We make all four. SP 6–32A ₹145, 40A ₹185, 63A ₹215. DP 6–32A ₹350, 40A ₹435, 63A ₹530. TP 40A ₹655 and 63A ₹815; FP 40A ₹855 and 63A ₹1,035, for three-phase supplies.

Whether a home needs a three-phase supply at all, what sanctioned load on the bill means, and kW vs kVA are explained in our single phase vs three phase guide.

An inverter circuit takes double pole protection too; our inverter for home guide shows where each MCB goes.

Why a single pole MCB goes in the phase and never the neutral is explained in our guide to phase, neutral and earth.

What does 10 kA breaking capacity mean?

10 kA breaking capacity means the MCB can safely interrupt a short-circuit current of up to 10,000 amps without being destroyed, which matters because a fault near the supply can briefly push thousands of amps through a circuit, far beyond the MCB’s 16A or 32A rating, and the breaker must clear it.

Household MCBs are made to IS/IEC 60898-1. Every MCB in our VIYONA 10 kA range carries a 10 kA breaking capacity and the BIS licence CM/L-2544151, printed in our catalogue beside each MCB. The rating and the breaking capacity are two different numbers: the rating (16A) is when it trips on overload, the breaking capacity (10 kA) is the worst fault it can survive.

For what happens inside the breaker as it clears a fault, from the magnetic coil to the arc chute, see our MCB working principle guide.

Check all three on the face of any MCB you buy: rating, breaking capacity and standard. Our guide on how to spot a fake ISI mark shows how to check a licence number.

How many MCBs does a 2BHK need?

A typical 2BHK needs one double pole incomer and about six to ten outgoing MCBs: one or two for lights and fans, two for general sockets, one for the kitchen’s heavy points, and one for each AC and each geyser, so a flat with three ACs and two geysers comes to ten, plus spare ways.

That count decides the board. Our SPN white line MCB box comes in 2–4 way ₹380, 6–8 way ₹480, 10–12 way ₹620 and 16–18 way ₹950, and the double door distribution box from 4 way ₹750 to 12 way ₹1,210 and 16 way ₹1,410. At MRP, ten 10 kA single pole MCBs (10 × ₹145 = ₹1,450), a 40A DP incomer (₹435) and a 10–12 way SPN box (₹620) come to ₹2,505, before wiring and labour.

The room-by-room points behind that count are in how to design a modern electrical layout.

The same count for a 1BHK and a 3BHK, and the price per way at each box size, is in our MCB box size list.

Does an MCB protect against electric shock?

No, an MCB does not protect against electric shock, because it responds only to too much current, and the current that flows through a person’s body is tiny compared with any MCB’s rating; protection against shock and earth leakage comes from an RCCB, which trips when current leaks to earth.

We do not make RCCBs, and we say so rather than blur the line. A well-protected home uses both: MCBs on each circuit against overload and short circuit, and an RCCB, commonly 30 mA for protecting people, on bathroom, kitchen and outdoor circuits or the whole board. Your electrician specifies the RCCB. A sound earth is what lets a fault trip the MCB quickly; see types of earthing. Our electrical safety tips for Indian homes cover the rest of the checklist. If someone does get a shock, our electric shock first aid guide gives the steps in order.

Signs your MCB is the wrong size

An MCB is probably the wrong size when it trips repeatedly on an ordinary load, or when it never trips while the wire, switch or socket on that circuit gets warm, because the first usually means an undersized breaker or an overloaded circuit and the second means a breaker too large for its cable.

Trips repeatedly: too many appliances on one circuit, a fault developing, or an undersized MCB on a heavy point. Never trips, wire gets hot: oversized for its cable, the more dangerous of the two. Warm or brown breaker: often a loose terminal rather than the rating.

Reading a trip pattern properly is its own job, so we keep it in one place: MCB tripping again and again: causes and safe checks. For heat at the wall, see switch getting hot or socket sparking. A yearly board check is part of our home electrical maintenance checklist.

Where to buy MCBs in India

We sell MCBs, isolators and boards through 500+ dealers across India, and dealers can order from us directly. There is no online shop: you buy from a dealer, by phone or by visiting. Everything in the VIYONA MCB range is made 100% in-house at our works in Marol, Andheri East, Mumbai.

The full range, with codes and MRPs, is on the VIYONA MCB page and the boards on the MCB distribution box page. To find a dealer near you, use the contact page.

Comparing makers rather than ratings is a separate question, and our guide to the best MCB brand in India sets out who sells MCBs nationally and what separates one from another.