TNB Electricity System
Voltages
The transmission voltage networks are 500kV, 275kV and 132kV, whilst the distribution
voltages are 33kV, 11kV and 400/230 volts. However, in the case of certain parts of Johor &
Perak, the distribution voltages may also include 22kV and 6.6kV.
Supply Frequency
The supply frequency is 50Hz ± 1%.
Earthing System
High Voltage and Extra High Voltage
3 phase configuration
Solidly earthed
Overhead lines and underground cable are used extensively for high and extra high
voltage distribution
Medium Voltage
3 phase configuration
Impedance-earth (NER)
Overhead lines and underground cable are used extensively for medium voltage
distribution
Low Voltage 400/230V
3 phase 4 wire system
Neutral point solidly earthed mixture of overhead lines, underground cables and aerial
insulated cables
Mixture of overhead lines, underground cables and aerial insulated cables
Short Circuit Ratings
As a guide, the maximum fault levels for the various voltage systems are as follows. All
equipment proposed to be installed and connected to TNB supply must comply with the stated
short circuit
ratings:
System Short circuit rating
for 3s
500 kV 50 kA
275 kV 40 kA
132 kV 31.5 kA
66 kV 20 kA
33 kV 25 kA
22 kV 20 kA
11 kV 20 kA
6.6 kV 20 kA
400/230 31.5 kA
V
Act, Regulation and Code
The electricity supply and installation practices in Peninsular Malaysia are governed by the
following:
Electricity Supply Act 1990 - Act 447
Licensee Supply Regulations 1990
Electricity Regulations, 1994
Occupational, Safety & Health Act 1994
Malaysian Standard MS IEC 60364 Electrical Installation of Buildings
Supply Voltage Options
Supply may be provided at any of the declared voltages: 275 kV, 132 kV, 33 kV, 22 kV*, 11 kV,
6.6 kV* and 400/ 230 V. * certain parts of Johor and Perak only Generally, supplies to domestic
premises are given at single phase 2-wire or three phase 4-wire. However, the actual supply
voltage provided depends on the magnitude of the individual applicant’s load requirements: Low
Voltage
Single-phase, two-wire, 240 V, up to 12 kVA maximum demand
Three-phase, four-wire, 415 V, up to 72kVA (100A) maximum demand
Three-phase, four-wire, C.T. metered, 400/230 V, up to 1000 kVA maximum demand
Medium Voltage & High Voltage
Three-phase, three-wire, 11kV for load of maximum demand 1,000 kVA to 5,000kVA
Three-phase, three-wire, 22kV for load of maximum demand 1,000kVA to 10,000kVA
Three-phase, three-wire, 33kV for load of maximum demand 5,000kVA to 25,000kVA
Three-phase, three-wire, 132kV and 275kV for exceptional high load maximum demand
above 25,000kVA
It should be noted that voltages other than the above classifcations cannot be provided by TNB.
However, consumers can make their own transformation arrangements where necessary.
All housing developers are encouraged to sign the SLA (Service Level Agreement). The
objective of the SLA is to ensure electricity supply is connected to housing projects within the
stipulated time to avoid delays in handing over houses to the purchaser. The SLA is open to all
housing developers applying for electricity supply for housing developments as prescribed under
the Housing Development (Control & Licensing) Act 1966. Commercial and industrial
development projects are not covered by the SLA. Timeframe allocated to complete the works is
not more than 18 months from the date of signing the Agreement, or shorter if mutually agreed
by both parties.
Typical timeframe for connection of supply within 18 months:
Roles and Responsibilities
What the Developer should do
1. Submit application form with the relevant documents required by TNB .
2. Sign SLA with TNB (provided all documents are in order) .
3. Pay connection charges upon notification from TNB within agreed timeframe.
4. Substation to be built and completed 4 months prior to electricity supply ready for connection.
What TNB should do
1. Sign SLA with developer
2. Issue Notice of Connection Charges within 2 months after SLA Agreement is signed
3. Commence works no later than 4 months prior to electricity supply ready for connection
Cost
The cost incurred is only the stamp duty. The Agreement should be stamped after execution by
both parties and each party should bear its own stamp duty, currently at RM10 per copy.
Penalty Clause
Compensation will be paid by both parties if they fail to fulfill their respective obligations under
the SLA.
