Ss 551 Code Of Practice For Earthing — Free Forever

SS 551 mandates specific testing methods—like the Wenner or Schlumberger methods—to measure how well the earth conducts electricity. It forces engineers to calculate the "step potential" (the voltage difference between a person’s feet) and "touch potential" (the difference between a hand and a foot). These aren't just numbers on a page; they are the mathematical difference between a minor tingle and a fatal cardiac arrest.

SS 551 defines earthing as the connection of exposed conductive parts (e.g., metal enclosures of equipment) and extraneous conductive parts (e.g., metal water pipes) to the main earth terminal. The primary objectives are: ss 551 code of practice for earthing

: Guidance on earthing at the boundary between high-voltage and low-voltage substations within buildings. Generating Sets SS 551 mandates specific testing methods—like the Wenner

SS 551 is generally than BS 7430 in sizing and more rigorous regarding bonding requirements due to Singapore’s lightning density (≈ 15–25 strikes/km²/year). SS 551 defines earthing as the connection of

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.

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SS 551 specifies that the earth resistance of for LV installations unless otherwise justified by calculation. However, for TT systems, a higher resistance (up to 200 ohms) is acceptable if RCDs with appropriate sensitivity (e.g., 30 mA, 100 mA, 300 mA) are used.