RCCB

There are two RCCB size that suitable for electrical wiring in house namely 40A and 63A. If you

house need plug socket and fan or light does not exceed 20 units and there is no powerful use of

electrical devices more 2000W, RCCB having size 40A real enough. If more than 20 units and

have 2000W electrical appliances on, RCCB 63A needed. Use RCCB with 100mA sensitivity.

RCCB

MCCB (Mounded Case Circuit Breaker)

It is to trip current may be adjustable. It rated current up to 1000A. Using a thermal or thermal

magnetic operation. Phase (line) and Neutral both wires connected through RCD. It trips the

circuit when there is earth fault current. The amount of current flows through the phase (line)

should return through neutral It detects by RCD any mismatch between two currents flowing

through phase and neutral detect by -RCD and trip the circuit within 30Miliseconed. If a house

has an earth system connected to an earth rod and not the main incoming cable, then it must have

all circuits protected by an RCD (because u might not be able to get enough fault current to trip a

MCB) RCDs are an extremely effective form of shock protection

MCCB

ELCB (Earth Leakage Circuit Breaker)

CHARACTERISTICS

Phase (line), Neutral and Earth wire connected through ELCB. ELCB is working based on Earth

leakage current. The safest limit of Current which Human Body can withstand is 30ma sec.

Suppose Human Body Resistance is 500Ω and Voltage to ground is 230 Volt. The Body current

will be 500/230=460mA. Hence ELCB must be operated in 30maSec/460mA = 0.65msec

Fuse and MCB characteristics

Fuses and MCBs are rated in amps. The amp rating given on the fuse or MCB body is the

amount of current it will pass continuously. This is normally called the rated current or nominal

current.The fuse and the MCB, even though their nominal currents are similar, have very

different properties. For example, for 32Amp MCB and 30 Amp Fuse, to be sure of tripping in

0.1 seconds, the MCB requires a current of 128 amps, while the fuse requires 300 amps. The fuse

clearly requires more current to blow it in that time, but notice how much bigger both these

currents are than the ’30 amps’ marked current rating. There is a small likelihood that in the

course of, say, a month, a 30-amp fuse will trip when carrying 30 amps. If the fuse has had a

couple of overloads before (which may not even have been noticed) this is much more likely.

This explains why fuses can sometimes ‘blow’ for no obvious reason.

JACK COMMANDO

Jack commando is a range of plugs and sockets of different sizes with differing numbers

of pins, depending on the current supplied and number of phases accommodated. The fittings

also include limited weather-proofing, that is one reason for choosing these fittings when the

connections will be used in open-air conditions; a further reason for using these (other than when

the heavy-current or three-phase facilities are actually needed), is to deter potential users from

connecting domestic appliances to the sockets, as 'normal' domestic plug-tops will not fit.

The cable connectors and sockets are colour-coded, according to the voltage range and

frequency used. Colour codes depend on the highest, phase-to-phase, voltage. In addition to the

colour-coding the voltage and frequency are encoded by the keyway position. The blue fittings

are often used for providing weather-proofed exterior sockets for outdoor apparatus. The yellow

fittings are used to provide transformer isolated 110 V supplies for UK construction sites to

reduce the risk of electric shock and this use spills over into uses of power tools outside of the

construction site environment. In camping situations, the large 32 A blue fittings provide power

to static caravans, whilst the smaller blue 16 A version powers touring caravans and tents. The

red three-phase versions are used for three-phase portable equipment.

Jack commando