Earth Leakage Circuit Breaker: Here’s What You Need to Know

An Earth Leakage Circuit Breaker is a safety device that is usually used in electrical installations with higher earth impedance as a safety measure to prevent electrocution. Most electrical installations have high earth impedance that can be due to the use of dry local ground conditions or the use of local earth rod. These installations can pose a safety risk in live-to-earth fault current, especially when there is not enough current to trip a circuit breaker or a fuse.  

When there is high impedance, it is not always possible for the earth line to maintain the voltage of exposed metal to safe proportions—this where ELCB can provide to be drastically helpful in reducing the risks. The Earth Leakage Circuit Breaker cuts the power of such installations when it detects such dangerous conditions.

Simply put, if a person touches a metal part or malfunctioning electrical equipment, which is at a relatively high voltage with respect to earth, then the electrical current will flow through your body to the ground. While the current is not enough to trip an electrical fuse to disconnect the electricity supply, it can be enough to kill a person. However, when an Earth Leakage Breaker Circuit detects even the smallest earth leakage, it disconnects the equipment.

What Are The Different Types of ELCB?

Generally, you will find these two types of Earth Leakage Circuit Breaker, they are:

- Voltage operated: these were introduced in the early 20th century as a major advancement to provide safety for mains electrical supplies with insufficient earth impedance.

- Current operated: These ELCBs are generally known as a residual current device (RCDs). They also protect against earth leakage, although their method of operation is different.

Connection Set-up

When an Earth Leakage Circuit Breaker is used, the earth circuit needs to be modified. The two earth terminals are connecting using the earth rod that is passed through the ELCB. One terminal goes to the installation earth circuit protective conductor, also known as CPC or the earth wire. Another connection goes to the earth rod. Hence, the earth circuit cuts via ELCB’s sense coil.

Operation

The ELCB is explicitly designed as a latching relay with the building’s main incoming power connecting through its switching contacts. As such, the Earth Leakage Circuit Breaker is able to disconnect the power when it detects unsafe leakage conditions.

Another task performed by ELCB is to identify fault currents from live-to-earth wire within the installation it is supposed to protect. If sufficient voltage shows up across the ELCB’s sense coil, then it will automatically cut the power and remain off until it has been reset manually. An ELCB, however, is unable to detect fault currents from live to any other earthed body.

The Advantages and Disadvantages of ELCB

The main advantage of Earth Leakage Circuit Breaker over RCD is that they are less sensitive to fault conditions. As a result, they experience fewer inconvenient trips.

ELCBs also have certain demerits. Some of them are listed below:

- They do not detect faults that do not pass current through the circuit protective current to the earth rod.

- It is impossible to split a single building system into multiple sections with independent fault protection due to earthing systems bonded to common pipework.

Earth bypassing

Usually, ELCB-protected installation to have an additional connection to earth somewhere, the one that does not pass through the Earth Leakage Circuit Breaker sense coil. This can be due to metal pipework in contact with the ground, metal structural framework, or home appliances in contact with the ground, among other things.

When this happens, the fault current can pass through the earth without being picked up ELCB. However, the good news is that despite that, the functioning of ELCB is not compromised. The main job of Earth Leakage Circuit Breaker is to safeguard earthed metalwork from rising to a dangerous voltage during fault conditions, and the ELCB continues to achieve that objective.

ELCB is a highly technical work that must only be performed by trained professionals. Be sure to seek their guidance for the installation and maintenance of the systems.