How we supply it: MCBs, RCCBs and distribution boards are arranged through a partner electrical dealer who quotes, supplies and bills them and pays us a referral commission. Your electrician's list of circuits goes to the dealer unchanged, so ratings and curves match the design.
In one line: An MCB (miniature circuit breaker) is an automatic switch that trips on overcurrent, while an RCCB (residual current circuit breaker) trips when the current going out on the phase and coming back on the neutral differ, meaning some is leaking to earth.
Two different kinds of protection
An MCB (miniature circuit breaker) is an automatic switch that trips on overcurrent, while an RCCB (residual current circuit breaker) trips when the current going out on the phase and coming back on the neutral differ, meaning some is leaking to earth.
MCBs follow IS/IEC 60898-1 and RCCBs IS 12640. An MCB protects the wire; a 30 mA RCCB protects the person touching a faulty geyser or wet switch.
Devices in a house board
| Device | Trips on | Typical use |
|---|---|---|
| MCB, B curve | Overload, short circuit; quick on surges | Lights, heaters, sockets |
| MCB, C curve | Overload, short circuit; tolerates start-up surges | AC, pumps, motors |
| RCCB 30 mA | Earth leakage, shock level | Sockets, bathrooms, kitchen |
| RCCB 100 or 300 mA | Larger leakage, fire protection | Whole-house incomer in some designs |
| RCBO | Overcurrent and leakage in one | A single critical circuit |
| Isolator or main switch | Manual only | Switching off the whole board |
| Surge protection device | Voltage spikes | Boards in lightning-prone areas |
How many RCCBs and how to group circuits
One RCCB for the whole house means any small leak, say an old geyser element, cuts every circuit. Splitting circuits under two RCCBs keeps half the house running.
Lighting can sit outside the RCCB group in some layouts so a trip at night does not leave the house dark; your electrician decides this against the design.
Board layout and ratings
Ratings above are typical; the electrician sets each one from the wire size and load.
- Order in the board: incoming supply, main switch or main MCB, RCCB(s), then circuit MCBs
- Typical ratings: lights 6–10 A, sockets 16 A, geyser 20 A, AC 16–20 A C curve
- Leave 20–30% spare ways for future circuits
- Separate neutral and earth bars, each tight and labelled
- A dedicated earth pit, designed per IS 3043, with its resistance measured
Checks after installation
- MCBs should be marked IS/IEC 60898-1 with curve and rating; RCCBs IS 12640 with sensitivity, such as 30 mA.
- Press each RCCB's test button: it must trip.
- Every MCB should be labelled with the circuit it serves.
- Ask for the earth-pit resistance reading taken with an earth tester.
- Check that neutral and earth bars are separate and the connections tight.
Placement and handling
- Keep breakers boxed until the board is fixed and nearby plastering is done.
- Mount the board away from water points and out of children's reach.
- Keep the board door shut against dust during finishing work.
Protection mistakes
- No RCCB at all, relying on MCBs to prevent shocks.
- One RCCB for the whole house, which trips often and then gets bypassed.
- B-curve MCBs on ACs and pumps, tripping at every start.
- No spare ways for future circuits.
- Earth wire taken to a water pipe instead of an earth pit.