: This section deals with the earthing of HV/LV substations, particularly those located within buildings. It covers Table 15 , which specifies "Acceptable bonding readings within distribution substations", ensuring the safety of personnel working in or near these high-energy environments.
The Definitive Guide to SS 551: Singapore Code of Practice for Earthing
Table 16 of SS 551 provides a ground-mounted plant installation model inspection form to assist in systematic inspection and documentation.
IEEE 80 (for HV substations), BS 7671 (for final circuits), and SS 555 (for lightning protection). ss 551 code of practice for earthing
To maintain compliance with Singapore regulatory bodies (such as the Energy Market Authority - EMA), installations must undergo regular periodic inspections and testing by a Licensed Electrical Worker (LEW). Core Testing Methods
: Protecting against electric shock by earthing the metal casings of appliances and equipment.
The conductor that connects the electrical installation to the earth electrode. : This section deals with the earthing of
SS 551 is the Singapore Standard that provides comprehensive guidelines for earthing electrical installations. It was formerly known as CP 5. The standard covers low-voltage installations, high-voltage systems, industrial premises, and specialized structures. Primary Objectives of SS 551
: Protective earthing and changeover switch arrangements for generators. Singapore Standards eShop SS 551:2022 - Singapore Standards
| Installation Type | Maximum Interval | |------------------|------------------| | Residential (landed / condo) | 5 years | | Commercial offices | 3 years | | Industrial plants / heavy machinery | 1 year | | Petrol stations / chemical plants | 6 months | | Lightning protection earths | 1 year (after each major storm) | IEEE 80 (for HV substations), BS 7671 (for
While specific installations vary, a general rule of thumb for standard low-voltage installations in Singapore is maintaining an earth electrode resistance for sub-stations, and generally under 10 Ohms for standard domestic or commercial structures, ensuring robust protection. 7. Compliance and Safety Checklists
An earthing system designed according to SS 551 serves three critical functions: