Four pole (FP) RCCB, 300 mA, 25A to 63A — earth-leakage fire protection for three-phase + neutral supplies and an upstream main RCCB; 415 V AC.
- Trips on an earth leakage of 300 mA — for fire protection and upstream use, not shock protection.
- Four pole (three phases and neutral), for three-phase 415 V AC, 50 Hz supplies.
- Rated current 25A, 40A or 63A — pick from the options.
- Test button — press it once a month; the RCCB must trip.
- Opens all poles together, including the neutral, when it trips.
- Does not trip on overload or short circuit — always install it with an MCB or fuse.
- 4 modules wide; snaps onto a standard 35 mm DIN rail.
An RCCB (residual current circuit breaker, often still called an ELCB) compares the current going out on the three phases and neutral with the current coming back, and switches the circuit off if part of it leaks to earth — through damaged insulation, a faulty appliance or a person.
A 300 mA RCCB is commonly fitted at the main incomer for fire protection: it cuts the supply when a persistent leak to earth, from damaged insulation or a failing appliance, is large enough to heat up and start a fire. Upstream of 30 mA RCCBs, it leaves small leaks to the local 30 mA device. It does not give the shock protection of a 30 mA RCCB.
It does not trip on overload or short circuit, so it always works with MCBs or fuses. Ratings in this listing: 25A, 40A and 63A — choose one at or above the MCB that protects it.
Which RCCB do I need
- DP for single-phase supplies; FP for three-phase + neutral supplies.
- 30 mA: protects people — homes, bathrooms and socket circuits.
- 100 mA: equipment protection and upstream RCCBs.
- 300 mA: fire protection at the main incomer.
Where to use it
- Main incomer RCCB for fire protection in three-phase buildings.
- Upstream of 30 mA RCCBs in the same board.
- Godowns, workshops, factories and commercial spaces.
How to install
- Switch off the main supply, confirm the board is dead, and snap the RCCB onto the DIN rail after the main MCB or isolator.
- Connect the supply to the LINE side and the outgoing circuits to the LOAD side, with the three phases and the neutral (N) on their marked terminals.
- Take every neutral of the protected circuits through the RCCB, and never join neutral and earth after it — either mistake makes it trip.
- Switch on, press the test button (the RCCB must trip), reset it and label the board.
Electrical work should be done by a licensed electrician. For AC circuits only.
Frequently asked questions
- Do I need an RCCB if I already have MCBs?
- Yes. MCBs trip on overload and short circuit; an RCCB trips on earth leakage — current escaping to earth through a fault or a person. A safe board needs both.
- Can I use a 300 mA RCCB in my home?
- Only upstream of 30 mA RCCBs, not instead of them: the CEA safety regulations of 2023 require a residual current device of 30 mA or less in homes.
- Which current rating do I need?
- One at or above the MCB or fuse that protects the RCCB. Typically 25A for a three-phase circuit or a small sub-board, 40A for a typical three-phase shop, office or workshop board and 63A for larger three-phase boards and main incomers.
- Will it trip together with a 30 mA RCCB below it?
- For small leaks, no — only the 30 mA device trips. On a large fault both can trip, as a standard RCCB has no time delay; full selectivity needs a time-delayed (S type) RCCB upstream.
- Why does my RCCB keep tripping?
- Usually a real leak: a faulty geyser element, washing machine or pump, damp wiring, or a neutral touching earth or shared with a circuit outside the RCCB. Switch off all MCBs, reset the RCCB, then switch the MCBs on one by one to find the faulty circuit.
Buy four pole 300 mA RCCBs online from Electric Market, Chennai. For site, contractor or bulk quantities, contact us for a quote.