2. IKRAM EARTHING 2
TUJUAN PEMBUMIAN
• Mengalirkan arus bocor kebumi dengan seberapa
banyak dan cepat supaya alat perlindungan, geganti
atau peranti perlindungan dapat berfungsi dengan
berkesan bagi mengelakkan berlakunya kejutan
elektrik
• Mendapatkan voltan rujukan kosong untuk star point
alatubah dan janakuasa supaya talian neutral dapat
digunakan dan voltan bekalan stabil serta
mengelakkan voltan terapong
• Mendapatkan voltan samaupaya (equipotential
voltage) supaya tidak berlaku step voltage bahan
pengalir yang terdedah (exposed conductive parts)
3. IKRAM EARTHING 3
CLASIFICATION OF EARTHING
SYSTEM
• Supply authority or supply source earthing
arrangement are indicated by the first
letter:
• T – one or more points of supply are
directly connected to earth
• I – supply system not earth, or one point
earth through a fault limiting impedance
4. IKRAM EARTHING 4
CLASIFICATION OF EARTHING
SYSTEM
• Relationship of exposed conductive parts
to earth are indicated by the second letter
• T – exposed conductive parts connected
directly to earth and which is independent
of the supply earth
• N – exposed conductive parts connected
directly to the earth point of the source of
the supply
5. IKRAM EARTHING 5
CLASIFICATION OF EARTHING
SYSTEM
• Arrangement of neutral and protective
conductors in T-N system is indicated by a
third letter
• S – separate neutral and protective
conductors
• C – neutral and protective conductors
combined in a single conductor
6. IKRAM EARTHING 6
EARTHING SYSTEM
• For normal installation practice, earthing is to
connect together the exposed conductive parts
of various items of the equipment to a common
terminal (main earthing terminal), this in turn is
connected by the earthing conductor to an earth
electrode, buried in the mass of earth
• The earth installation must be capable must of
carrying the prospective fault currents without
danger and without excessive heat. It must have
low resistance at all times with good resistance
to corrosion
7. IKRAM EARTHING 7
ELECTRODE
• The most important part of the earthing system
is the electrode
• Electrode are made from a number of materials
like cast iron, steel, copper or stainless steel and
they may be in the form of plate, tubes, rods or
strips
• The most favored material is copper which has
good conductivity, is corrosion resistance to
many of the salts that exist in the soil and it is a
material that is easily worked
8. IKRAM EARTHING 8
ELECTRODE
• These consist of some form of deeply
buried conductor, since the major earth
resistance lies on the top soil
• Buried copper or galvanized earth plate
have largely given place to threaded
copper-clad steel-cored rods
9. IKRAM EARTHING 9
TYPES OF ELECTRODE
• Earth rods or pipes
• Earth tapes or wires
• Earth plates
• Earth electrodes embedded in foundation
• Metallic reinforcement of concrete structure
• Metal pipes
• Lead sheaths or other metallic covering of
cables
10. IKRAM EARTHING 10
EARTH RESISTANCE
• The earth resistance depends on soil
resistivity and characteristic. The type of
soil suitable for earth electrode are:
• Wet marshy ground
• Clay, loam soil, arable land
• Clayey soil, loam mixed with small quantity
of sand
• Damp and wet sand
11. IKRAM EARTHING 11
EARTH RESISTANCE
• Achieving a good earth will depend on
local soil condition. Three factors that
affect the soil resistivity are:
• Moisture content of the soil
• Chemical composition of the soil
• Temperature of the soil
12. IKRAM EARTHING 12
EARTH RESISTANCE
• In area of high soil resistivity, it is difficult
to obtain an earth resistance say one ohm
or less. Several option are available in the
form of soil conditioning agent e.g copper
sulphate, sodium carbonate, bentonite and
marconite
13. IKRAM EARTHING 13
APA YANG PERLU DIBUMIKAN
• Semua peralatan elektrik yang dibuat dari
logam atau bahan yang boleh mengalirkan
elektrik, samada alatan elektrik ataupun
bukan
• Star point alatubah dan janakuasa
• Terminal bumi DB, lampu, soket 13A, dsb.
• Konduit, trunking, tray, riser, busduct, dan
apa-apa jua bahagian logam pemasangan
elektrik
22. IKRAM EARTHING 22
AVERAGE RESISTIVITY OF THE
EARTH
Type of Earth Resistivity/Ohm-meters
Wet organic soil 10
Moist soil 100
Dry soil 1000
Bed rock 10000
23. IKRAM EARTHING 23
JENIS KABEL BUMI
• PVC hijau
• PVC hitam untuk star point janakuasa
• Pita tembaga (copper tape) – 3mm x
25mm
24. IKRAM EARTHING 24
SAIZ KABEL BUMI
• Sama dengan saiz kabel fasa sehingga
16mm²
• 16mm² jika saiz kabel fasa diantara 16mm²
hingga 35mm²
• Separuh dari saiz kabel fasa jika saiz kabel
fasa melebehi 35mm²
• Gunakan pita tembaga 3mm x 25mm jika
saiz kabel bumi melebehi 70mm²
• CENTRAL earthing bar 50mm x 6mm
33. IKRAM EARTHING 33
JENIS-JENIS ELEKTROD
BUMI
• Standard copper-jacketed steel core earth
rod 16mm diameter and 1500mm long
• G.I pipe 2 in diameter
• Wire mesh
• Building steel reinforcement
• Javelin rod (overhead line)
35. IKRAM EARTHING 35
RINTANGAN ELEKTROD BUMI
Elektrod bumi pemasangan 1 ohm
Elektrod bumi penangkap kilat 10 ohms
Transformer and generating station
10,000 kVA and over
2 ohms
Small transformer stations and
distributing stations
10 ohms
Small outdoor station 15 ohms
Distribution transformer installation 25 ohms
