Ss 551 Code Of Practice For Earthing [2021]

Earthing provides a stable reference point (zero potential) for the electrical network. This prevents the voltage of the system from drifting dangerously high during normal operations, transient events, or unbalanced load conditions. Dissipation of Lightning and Surge Energies

In HV environments, the magnitude of fault currents is immense. SS 551 aligns with stringent standards to calculate (the voltage between a person's feet) and Touch Potential (the voltage between a person's hand and foot during a fault). Substation earthing grids must be designed using advanced modeling software to ensure these values never exceed human tolerance thresholds. Medical Facilities and Operating Theatres

: Safe structural grounding zones where high-voltage utility lines step down to low-voltage internal distribution boards within buildings. ss 551 code of practice for earthing

SS 551 mandates a stronger emphasis on touch and step potential calculations for substations and high-fault-current installations, rather than simply relying on achieving an arbitrary low resistance (e.g., 1 Ω).

applies to:

Crucially, the code does not apply to earthing for lightning protection systems (covered under SS 555) or special installations like explosive atmospheres (SS 60079 series), though it references them where interfaces exist.

). SS 551 emphasizes that soil resistivity varies widely based on geographic location in Singapore, soil type (clay, sand, granite), moisture content, and temperature. Earthing provides a stable reference point (zero potential)

SS 551 specifies that the of an installation’s electrode(s) shall be sufficiently low to: