M.C.B.s (Miniature Circuit Breakers) – Hidden current eaters

In modern electrical wiring of a home or office, providing M.C.B.s at various points of distribution is very common. This facility is very useful in case of overload or short circuit and saves the wiring from damages but it consumes power constantly just to be ready for automatic shutoff of power and therefore needs careful consideration before installation in view of the need for saving electricity.

This facility automatically protects an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.

Installing M. C. B. s in an electrical installation has a justification but the number and ratings have to be decided very judiciously as they are constant current eaters. Although, the consumption is low bu it is 24 hours a day and 365 days of a year.

As per IS:8828 -1996, the allowable electric consumption is 3 to 13 Watts for the M.C.B. ratings ranging from 6 to  63 amperes.  Common ratings and power consumption is as under –

Rating (Amp)       Power consumption (Watt)

16                                                 3.5

25                                                 4.5

32                                                 6.0

40                                                 7.5

So, if unnecessary M.C.B.s are installed or the ratings are higher than that required as per estimated load on the circuit, then the system will wastefully consume power.

For example, if 10 M.C.B.s in a system of average 25 ampere rating  are found to be installed unnecessarily, then it will consume 45 watt of power for all the time and the yearly consumption will be 394.2 kilowatts costing about Rupees 2000/- considering a rate of Rs. 5/- per kilowatt.

So, please check your existing electrical installation and be cautious when getting new electrical installation so that only minimum required M.C.B.’s of optimum ratings are fixed so as to save costly electricity. You can also go for old fuse system where you can afford to reset the fuse by putting a new fuse wire manually instead of just resetting the button of an M.C.B.