RCCB Vs. MCB: A Quick Comparison Guide

The RCCB and MCB are both circuit breaking devices. But while they both provide protection functions, there are several differences between them, as this RCCB vs. MCB guide will explain. Get to know these breakers differ in terms of construction, working, protection features and capabilities, cost, application, and more.

RCCB MCB Full Form

RCCB stands for Residual Current Circuit Breaker. On the other hand, MCB stands for Miniature Circuit Breaker. To understand why these two breakers are called different names, here’s a quick overview of their meanings.

Meaning of RCCB

The meaning of RCCB in electrical systems traces to the type of current it’s meant to handle. RCCBs are designed to protect people and equipment from dangerous levels of residual current, which is a type of fault current that flows through the circuit even when the power switch is off or disconnected.

This type of current can happen due to insulation failure or other hazards inside the electrical system, and can be fatal in some cases. RCCB use, therefore, helps open the circuit in time to prevent fatal shocks or fires.

Meaning of MCB

MCBs are called so for their compact size that’s intended to fit into tight spaces. An MCB is also designed for lower current and voltage levels such as may be found in domestic and some commercial applications.

MCBs primarily protect circuits from overload and short circuit currents, but cannot detect the presence of residual current like the RCCB breaker can. Continue below to learn more about the difference between MCB and RCCB circuit breakers.

RCCB Vs. MCB

When it comes to the protection features, there is a notable difference between RCCB and MCB breakers: RCCBs are designed for protection against dangerous levels of earth leakage current, whereas MCBs are meant to offer protection against overcurrents. This RCCB vs. MCB comparison will help understand the differences in more detail.

RCCB Vs. MCB: Construction

RCCB and MCB breakers have different construction features. RCCBs use a special type of sensing coil that detects ground faults in a circuit, and will trip to cut off power if the levels are too high.

MCB breakers, have sensitive electromagnets inside them that react to short-circuits and will accordingly trip to cut off the power. A typical MCB will also come with a thermal device that will detect any overloading of the circuit.

RCCB Vs. MCB: How it Works

The RCCB working principle is also different from that of miniature circuit breakers. An MCB will trip if the current in the circuit is higher than what it’s rated for, such as during an overload or short-circuit. The RCCB will sense any leakage of residual current and break the circuit when unsafe levels are detected.

In essence, RCCBs use what’s called the Kirchhoff’s Law of Current Conservation, which states that the sum of all currents entering a node must equal the sum of all currents leaving it. In this case, the breaker senses incoming and outgoing currents in the live and neutral wires.

RCCB Vs. MCB: Tripping Time

The RCCB and MCCB difference is also seen in their trip curves. The trip curve of an RCCB is typically much faster than that of an MCCB. This is because current leakage can be dangerous and needs to be detected quickly in order to prevent harm.

In contrast, an MCCB can have a slower response to fault since it generally prevents circuit and equipment damage. This is also to prevent nuisance trips such as those caused by short-lived power surges.

RCCB Vs. MCB: Protection

As mentioned earlier, RCCB and MCB breakers offer different types of protection. RCCB protection mainly involves detecting and protecting persons from potentially deadly levels of leakage currents.

On the other hand, an MCB will detect overcurrents and trip accordingly. This means RCCB circuit breakers can provide better protection against earth faults than an MCB, and must be used alongside it.

RCCB Vs. MCB: Cost

When it comes to cost, the RCCB tends to be more expensive than an MCB. However, in spite of the higher cost of RCCB breakers, they’re easy to maintain, seeing that they come installed with a test button.

The range of RCCB price depends on several factors: rating or size, type of RCCB, etc. Generally, you can expect to spend from around $30 to over $100 per breaker. MCBs generally cost less with the actual price depending on the breaker rating and other factors.

RCCB Vs. MCB: Applications

When it comes to applications, both RCCBs and MCB breakers are mostly used in domestic electrical systems. These are systems where the current levels are lower than industrial applications.

RCCB use typically includes in the circuits of bathroom fixtures and kitchen equipment. Also, in other areas of a home or commercial place that require extra protection due to the presence of water and other potential ground fault hazards.

RCCB MCB Connection

RCCB and MCB breakers are normally used together. That means the RCCB will provide detection and protection from leakage faults, while the MCB will offer overload and short-circuit protection. The two must be wired together for them to work properly.

To ensure their proper operation, the RCCB MCB connection is typically such that the MCB trips first before. That’s because the RCCB is more sensitive and needs to be protected against the dangers of overcurrents.

For example, and as shown in the above RCCB wiring diagram, the MCB should is connected in series with the RCCB. This way, if either an overload or short-circuit occurs, the MCB will trip first and protect the more delicate RCCB.

Conclusion

The difference between RCCB and MCB breakers is seen in many aspects, from their construction and working principles to their protection levels and applications. RCCBs are, however, more sensitive and provide better protection against earth faults. Given their different functions, though, both breaker types should be used in an electrical system for complete protection. Only ensure the right rating for either device, as incorrect ratings can cause false trips or inadequate protection.