TNB Electricity Supply System
A practical reference to TNB system voltages, supply frequency, earthing arrangements, short-circuit ratings and supply voltage options for business and industrial premises.
TNB Electricity Supply System
This page provides a practical overview of the electricity system used by Tenaga Nasional Berhad (TNB) for business and industrial electricity supply in Peninsular Malaysia. Final supply arrangements remain subject to TNB technical assessment, load requirements and the applicable regulations.
System Voltages
| Network | Nominal voltage |
|---|
| Transmission | 500 kV, 275 kV and 132 kV |
| Distribution | 33 kV, 11 kV and 400/230 V |
| Certain parts of Johor | 22 kV and 6.6 kV |
Supply frequency: 50 Hz ± 1%.
Earthing and Distribution
| Voltage category | Configuration | Earthing |
|---|
| High and extra-high voltage | Three phase | Solidly earthed |
| Medium voltage | Three phase | Impedance-earthed using a neutral earthing resistor (NER) |
| Low voltage 400/230 V | Three-phase, four-wire | Solidly earthed |
Overhead lines and underground cables are widely used across high, medium and low-voltage distribution networks.
Maximum Short-Circuit Ratings
| System | Maximum fault level |
|---|
| 500 kV | 50 kA for 1 second |
| 275 kV | 40 kA for 3 seconds; up to 50 kA for 1 second at specified substations |
| 132 kV | 31.5 kA for 3 seconds; up to 40 kA for 3 seconds at specified substations |
| 33 kV | 25 kA for 3 seconds |
| 22 kV, 11 kV and 6.6 kV | 20 kA for 3 seconds |
| 400/230 V | 31.5 kA for 3 seconds |
Supply Voltage Options by Maximum Demand
| Supply arrangement | Typical maximum demand |
|---|
| Single-phase, two-wire, 230 V | Up to 12 kVA |
| Three-phase, four-wire, 400 V | Up to 72 kVA (100 A) |
| Three-phase, four-wire, CT-metered, 400/230 V | Up to 1,000 kVA |
| Three-phase, three-wire, 11 kV | 1,000 to 5,000 kVA |
| Three-phase, three-wire, 22 kV | 1,000 to 10,000 kVA |
| Three-phase, three-wire, 33 kV | 5,000 to 25,000 kVA |
| Three-phase, three-wire, 132 kV or 275 kV | Exceptional loads above 25,000 kVA |
TNB states that voltages outside these classifications are not normally provided. Where necessary, a customer may need to arrange its own voltage transformation equipment, subject to TNB approval.
Before Selecting an Industrial Property
- Confirm the required connected load and maximum demand with your electrical consultant.
- Check the available supply voltage and spare capacity with TNB for the specific site.
- Allow for any required substation, switchgear, metering, cabling and connection charges.
- Refer to the current Electricity Supply Application Handbook (ESAH) and obtain TNB approval before finalising the electrical design.
Source: TNB Electricity System. This page is a general reference only. Please verify current technical and regulatory requirements directly with TNB and qualified professionals.
DISCLAIMER : ALL INFORMATION, ARTIST IMPRESSIONS, ILLUSTRATIONS, PHOTOGRAPHS, SHOW UNITS, LANDSCAPE FACILITIES, FLOOR PLANS, AND RELATED MATERIALS ARE FOR REFERENCE ONLY. WHILE TRANSLATING AND COMPILING THE INFORMATION ON THIS WEBSITE, WE ARE UNABLE TO FULLY GUARANTEE ITS ACCURACY, TIMELINESS, OR COMPLETENESS. ALL SUBJECT TO THE OFFICIAL SOURCES. FOR INTERESTED PARTIES, WE WILL ASSIST IN ARRANGING SITE VISITS AND MEETINGS WITH THE OFFICIAL REPRESENTATIVES TO OBTAIN MORE COMPLETE AND DETAILED INFORMATION.
