Under sizing the earthing system involves using conductors or electrodes that are inadequate in size or capacity to handle fault currents effectively. This can occur due to various reasons, such as cost-cutting measures, lack of understanding of system requirements, or improper design and installation practices. Regardless of the cause, the consequences of undersized earthing systems can be severe and far-reaching. 

One of the primary dangers of undersized earthing systems is the increased risk of electrical shock to personnel. During a fault condition, such as a short circuit or ground fault, the fault current seeks the path of least resistance to return to its source. If the earthing system is undersized, it may not be able to handle the magnitude of the fault current, leading to elevated voltages on conductive surfaces and creating a hazardous situation for anyone in contact with them. 

Furthermore, undersized earthing systems can compromise the proper functioning of protective devices, such as circuit breakers and fuses. These devices rely on the earthing system to effectively clear faults by providing a low-impedance path for fault currents. If the earthing system is undersized, it can result in delayed or ineffective operation of protective devices, prolonging the duration of faults and increasing the risk of electrical fires and equipment damage. 

Inadequate earthing can also have detrimental effects on sensitive electronic equipment and systems. Without a robust earthing system to dissipate fault currents, equipment may be subjected to transient voltages and electromagnetic interference, leading to malfunctions, data corruption, and premature failure. In industries where uninterrupted operation is critical, such as healthcare, manufacturing, and telecommunications, the reliability of the earthing system is paramount. 

Moreover, undersized earthing systems can compromise the integrity of the electrical infrastructure as a whole. Excessive fault currents flowing through undersized conductors can cause overheating, insulation degradation, and mechanical stress on electrical components, potentially resulting in catastrophic failures and widespread outages. The financial and operational costs associated with repairing and replacing damaged equipment and restoring the service can be staggering. 

To mitigate the risks associated with undersized earthing systems, proper design, installation, and maintenance practices are essential. Engineers and designers must accurately calculate the fault currents expected in the system and size the earthing components accordingly. This involves selecting appropriate conductor sizes, electrode types, and grounding configurations to ensure adequate fault current dissipation. 

Additionally, regular testing and inspection of the earthing system are crucial to verify its effectiveness and identify any deficiencies or deterioration. Ground resistance measurements, continuity tests, and visual inspections can help detect issues such as corrosion, loose connections, or damage to electrodes, allowing for timely corrective actions to be taken.