Ss 551 Code Of Practice For Earthing ~upd~ -

By December 28, 2025Resetters

Ss 551 Code Of Practice For Earthing ~upd~ -

SS 551 — Code of Practice for Earthing (Draft Outline)

1. Scope and Purpose

  • Defines requirements for design, installation, testing, and maintenance of earthing systems for electrical installations in buildings and infrastructure.
  • Ensures protection of people, livestock, property, and equipment from electric shock, fire and overvoltages.
  • Applies to low-voltage (≤1 kV) and associated bonding; references for medium- and high-voltage where relevant.
  • Practical Guidance: For most commercial installations, SS 551 Appendices suggest that a value of 1 Ohm or less is desirable for installations above 100 A supply, but 5 Ohms or less may be acceptable for smaller domestic supplies.
  • Lightning Protection (SS 555 interface): If the earthing system is shared with a lightning protection system, the combined resistance must be less than 10 Ohms, but lower values (1-5 Ohms) are strongly recommended.

    • , it is tailored to meet local regulatory and technical requirements in Singapore. The primary objective of the code is to ensure the safety of human life, animals, and property by limiting electrical potential during fault conditions. Scope and Exclusions

    Connecting non-current-carrying metalwork to earth to protect against electric shock. ss 551 code of practice for earthing

    All test results must be recorded in an Electrical Installation Test Report (as per SS 638 / EMA requirements). SS 551 — Code of Practice for Earthing (Draft Outline) 1

    Generator Arrangements: Includes rules for protective earthing and changeover switch arrangements for generator sets. including earth rods

    Earth Electrodes: Provides design guidance for various types, including earth rods, plates, and foundation electrodes.

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