Ss 551 Code Of Practice For Earthing
The central point where all earth conductors for an installation are connected.
SS 551 governs the following aspects of electrical earthing:
The earthing grid must be designed to keep both voltages well below thresholds that can cause ventricular fibrillation in humans. Sizing Earthing Conductors
SS 551 isn't a "one size fits all" document. It provides specific guidance for various scenarios: ss 551 code of practice for earthing
The central hub within a building's electrical switchroom or consumer unit where all earthing and bonding conductors are securely connected. Circuit Protective Conductors (CPC)
| Type | Material | Minimum Dimensions | Notes | |-------|----------|--------------------|-------| | Rod | Copper-bonded steel, stainless steel | 14 mm diameter, 1.2 m driven depth | Most common | | Plate | Copper, galvanized steel | 600 mm × 600 mm × 3 mm | Requires excavation | | Tape / Strip | Copper | 25 mm × 3 mm | Laid in trench | | Foundation earth electrode | Reinforcing steel | Per structural design | Must be welded or tied for continuity |
The standard path to validating an earth electrode's effectiveness is the (3-terminal test). The central point where all earth conductors for
Disclaimer: This article is for informational purposes only. Always refer to the latest official SS 551 document and consult a licensed electrical engineer for specific installations.
An earthing system is only as good as its documentation. SS 551 mandates specific tests after installation and at regular intervals:
: Standards for protective earthing and changeover switch arrangements for low voltage generators. It provides specific guidance for various scenarios: The
The standard dictates acceptable resistance values (typically under 1 Ohm for substation earthing and specific low-voltage installations) to ensure effective protection.
: Specific clarifications on earthing methods to match the requirements of Singapore’s power grid operators. Common Exclusions It is important to note that SS 551 does Ships, aircraft, or offshore rigs.
SS 551 is more rigorous than BS 7430 but less detailed than IEEE 80 for high-voltage substations. For lightning, it defers appropriately to SS 555.
Rejection of electrical installations by the Licensed Electrical Worker (LEW) or authorities. Increased risk of electrical fires. Legal liability in the event of an electrical accident. Conclusion
is not just a matter of compliance—it's a matter of life and safety. Proper earthing ensures that if a fault occurs, the current has a safe path to the ground, protecting both the people inside the building and the expensive machinery powering it. For professionals, staying updated via the Singapore Standards e-shop