QCI Interview Question from SAPID
1.
Introduce
yourself. Tell me about your credentials and experience.
2.
What
is the role and responsibility of the QC inspector?
- I
will be responsible for preparing and verify the quality procedure is approved
by the Company
- I
will be responsible for verifying the standard revision date or cut-off date to
be used
- I
will be responsible for checking the ITP if not available in Aramco ITP then we
will prepare a suitable ITP and checklist to be submitted to the company for
approval
- I
will be responsible for conducting the internal inspection of the construction
activity before raising RFI to SAPMT and SAPID for final inspection
- I
will be responsible for communicating to SAPID and SAPMT about any inspection
activity and any non-conformance found on the site
- I
will be responsible for conducting daily site surveillance, especially for the
material used to ensure no substandard materials are used at the site and for
the technician skills that work to be done to be workmanlike work.
- I
will be responsible for conducting quality talks or toolbox talks with site
personnel weekly to introduce the lessons learned and best practices from
previous projects and standard requirements.
- I
will be responsible for issuing proactive notifications on site for construction
activity to ensure the construction complies with the standard requirements.
- I
will be responsible for issuing INCR for any non-conformance and/or violation
found, identifying the root cause, providing proposed corrective action, and
coordinating with the company and construction team for issuance and closure of
INCR.
- I
will be responsible for conducting a Kick-off meeting before any construction
activity starts.
- I
will be responsible for issuing RFI in EPM and closing the RFI’s in EPM
- I
will be responsible for monitoring and closing the RFI comments and PMCC punch
items.
3.
What
documents need to be reviewed by the QC Inspector?
- Scope
of work
- Drawings
to ensure it was IFC
- Standard
revision date or cut-off date to be used
- ITPs
and checklist to be used if any activity without ITPs and checklist will
prepare suitable ITPs and checklist to be submitted to the company for
approval.
- Quality
procedure if approved by the company
- INCRs
and LBE for issuance and corrective action
- SAT
test report
- Motor
Solo run package
- Energization
package
4.
What
are the contents of the Energization package?
- Table
of contents
- Energization
certificate form
- Construction
drawings such as SLD, Connection diagram, Cable schedule, and Grounding drawing
- Vendor
drawings such as Equipment General Arrangement
- Installation
RFI of the Electrical Equipment
- SAT
RFI of the Equipment
- Power
and control cable test report RFI
- Power
and control cable torque test
- Grounding
test report RFI
- Grounding
torque test
- Final
Inspection RFI
5.
What
are the contents of the Motor solo run package?
- Table
of contents
- Authorization
of Motor Solo run
- Construction
drawings such as SLD, Connection diagram, Cable schedule, and Grounding drawing
- Vendor
drawings such as General Arrangement of Motor and Datasheets
- Installation
RFI of the Motor
- Mechanical
Releases such as Motor Alignment and RFI for Greasing
- Routine
test RFI of the motor
- Power
and control cable test report RFI
- Power
and control cable torque test
- Grounding
test report RFI
- Grounding
torque test
6.
For
the new substation what the Electrical requirements are before start?
- Checked
the length of the substation must be 75 length and 15 width
- Checked
the drawing must be IFC
- Checked
the embedded channel is correct as per the survey report
- Checked
the conduit sleeved location and size as per the IFC drawing
- Checked
the stub-up conduit and sized it as per IFC drawing
7.
How
to perform an inspection of the installation of Switchgear and MCC
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- During
installation activity by construction team needs to conduct daily site
surveillance so that they comply with per manufacturer's instructions and for
any possible damage.
- Conduct
pre-inspection of the installation to verify the spacing requirements and the
anchoring.
- Once
all requirements are followed as per standard requirements then an RFI will be
issued to SAPMT and SAPID
8.
What
is the space requirement for switchgear and MCC
- AIS
Switchgear 2 meters front and 1 meter back and side
- Control
gears 1.5 meters in front and 1 meter on both sides.
9.
How
will you ensure that the bus bar installation in switchgear is correct?
- Will
conduct closed monitoring and verify the vendor assembly drawing that the
correct allocated bus bar size, rating, and thickness was installed on that
specific section of the switchgear and then verify the overlapping and
alignment of the bus bar.
10. How to perform an inspection
of a duck bank?
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- Checked
the PVC conduit materials and fittings used are correct if the conduit is TC2
the fittings must be TC3
- Checked
the conduit to form works that have a 75mm outside surface for concrete to any
conduit or reinforcing steel
- Checked
the spacer intervals of 2.4 meters and conduit separation of 50 mm for 50.8 mm (2 inches)
conduits and larger, and 25 mm for 38.1 mm (1½ inch) conduits and smaller.
- Checked
that the bell end was installed on the end of the conduit, rope and a blind or
plug must be installed to protect during concrete pouring.
- Checked
the quantity of conduit as per drawing is correct with a minimum of two spare
ducts.
- Need
to check proper anchoring of the conduit to avoid movement during concrete
pouring
11. What are the types of conduit
and fittings allowed to be used for duct bank
- Type EB-35 or DB-120 (minimum modulus of
elasticity 3450 MPa (500,000 psi)) per NEMA TC 6 & 8 and fittings are TC 9 or
Type EPC-40-PVC per NEMA TC 2 and fittings are TC 3.
12. What are Separation of 4” PVC
Conduit in duct bank
-
Separation of 50 mm for 50.8 mm (2 inch) conduits and
larger
13. What is the spacer distance
in the duct bank
-
Spacers shall be used at intervals not exceeding 2.4
meters.
14. How you will check the 5mm
thickness of the red die of the duct bank
- After
concrete pouring for the top finishing the concrete must be mixed with red dye
and we will check it and measure on the edge of the form works that it was 5mm.
15. How you will do the mandrel
test?
- Mandrel
test of the duct bank conduit will be performed before and after the concrete
pouring.
16. How will you inspect
substation grounding?
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
will check trench depth and the grounding should be soft or annealed bare
copper.
- Before
cad weld we will inspect the mold and powder used we will record and monitor
the mold usage.
- I
will witness during cad welding that the correct mold and powder were used as
per connection and after the connection we will verify the integrity of the cad
weld connection must be clean the joint before applying the bituminous tape.
- Once
cad weld is done we will apply bituminous tape on the cad weld joint then PVC
green tape.
17. What grounding materials will
be used in a substation in a low resistivity soil?
- Soft
or annealed bare copper.
18. How will you test the
integrity and what are the acceptances of grounding?
- Conduct
grounding resistance test
19. For the grounding system how
much is the resistance for the individual grounding rod, substation grounding,
and structure grounding?
- Individual
grounding rod – 25 ohms, substation grounding solidly below 1 kV – 5 ohms,
substation grounding solidly above 1 kV – less than 1 ohm or 1 ohm, and
structure grounding – 5 ohms
20. How will you start inspecting
a 13.8kV & 34.5kV cable termination?
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
will check the personnel qualifications of the splicer are approved by the
company with a JCC card.
- I
will check the kit used is approved and kV rating of the kit is as per the
rated voltage of the cable and that the cable lugs are approved.
- The
activity should be witnessed by SAPOD power
21. What are the creepage
distances inside a medium voltage motor terminal box?
- Minimum creepage distance to the ground of 25
mm per kV line-to-line nominal system voltage.
22. What is INCR, what are the
contents of INCR and what are the critical INCR you issued from your previous
project
- INCR
is the internal none non-conformance report and is the tool of the QC inspector
to report any non-conformance or violation found during site surveillance or
pre-inspection activity.
- The
critical INCR that I was issued in my previous project was the grounding cable
that was pulled from NGR to the Transformer, which is 120mm2 and the vendor
recommendation of NGR is 400mm2 The root cause Engineering was not anticipated
the vendor requirements and/or vendor recommendation for the grounding size and
requirements as per project specification and standard.
Another Question from QCI
1.
Color
coding of Cable?
- Shall
be identified by color coding to be synchronized as per Saudi Building Code as
Black, Brown, and Grey
2.
Depth of
trench in MV cable and the test to be conducted?
- Direct
buried – 920mm, Direct buried with PVC or HDPE – 610mm, and Duct back – 460mm.
- Test
to be conducted – Continuity and IR Test, Hi-pot Test, and for direct buried
the integrity of the over sheath (overall jacket) of direct buried cables rated
5 kV and higher shall be tested by conducting a 5 kV DC Insulation resistance
test.
3.
How
much is the depth of the cable trench for EHV cable and what is the test to be
conducted?
- Direct
buried – 1070mm, Direct buried with PVC or HDPE – 760mm, and Duct back – 460mm.
- Test
to be conducted – Continuity and IR Test, Hi-pot Test, and for direct buried
the integrity of the over sheath (overall jacket) of direct buried cables rated
5 kV and higher shall be tested by conducting a 5 kV DC Insulation resistance
test.
4.
How
will you inspect a Power transformer?
- First
need to check quality procedure is approved before starting the construction activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
we will inspect the foundation released by the Civil team
- I
we will check the distance for MV transformer from the Power Transformer to the
substation building has a fire rating is 6.1 meters or greater. If no fire
barrier or barrier fire rating is less than 1 hour greater than a minimum of
15.2 meters of clear space.
- I
we will check the distance for MV transformer from transformer to transformer 7.6 m (7,570 and
18,930 liters transformers) and 15.2 m (>18,930 liters transformers)
- Checked
the Transformer oil
containment and/ or drainage systems shall be provided for oil-filled equipment
containing more than 2,500 liters of oil.
- The crushed rock shall be uniformly graded
having a sieve size between 25 mm and 60 mm
- The steel grating mesh shall have a sieve size
of less than 25 mm.
- A sump shall be provided at a corner of the
pit for the collection of rainwater or oil
- Then
we will check the grounding connection must be two connections on the opposite
side
- We
will check the centering of the transformer.
- We
will check the stub-up conduit on the exact position on the termination box
5.
What
are the tests required to power a transformer?
- Winding
resistance per taps, Insulation resistance, Polarization Index, Turn ratio per
taps, Excitation, Tan Delta, Oil test, Buchholz relay test, Winding temperature
indication test, Oil temperature indicator test, cooling fan functional,
Protection functional test, Stability test.
6.
What
is the distance of a transformer installation from a substation?
- The
distance from the Power Transformer to the substation building has a fire
rating is 6.1 meters or greater. If no fire barrier or barrier fire rating is
less than 1 hour greater than a minimum of 15.2 meters of clear space.
7.
What
is the transformer working clearance Power Transformer?
- 2
meters in all side
8.
What
is the requirement to install an oil containment pit of a power transformer?
-
Shall be designed to withstand a minimum of 3 hours of fire
occurring within the bounds of the containment system.
- Oil containment shall be in the form of a
concrete pit constructed around the transformer foundation to contain 110% of
transformer oil.
-
The pit shall be equipped with a steel grating covered
with crushed rock to a minimum thickness of 300 mm
-
The crushed rock shall be uniformly graded having a sieve
size between 25 mm and 60 mm
-
The steel grating mesh shall have a sieve size of less
than 25 mm.
9.
How
to perform an inspection of the conduit installation
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
will check the conduit size used as per IFC drawing and area classification
- I
will check the conduit fittings used were not counterfeit materials
- I
will check the field cuts conduit is clean and coated with a zinc-rich
protective coating
- I
will check the support and securely fasten of the conduit must be 300mm.
10.
What
are the types of conduits it uses?
- RGS
conduit - can be used in non-hazardous and hazardous locations
- RGS
PVC coated conduit – Corrosive area and direct buried
- EMT
conduit – Can be used indoor
- PVC
conduit – can be used for duct bank, direct buried, and stub ups
11.
EMT
conduit where we use.
- Indoor
used
12.
How
much depth of the trench for PVC conduit
- 600V
below is 460mm, over 600V to 35kV is 610mm and over 35kV – 760mm
13.
How
much is the fill percentage of the conduit?
- 40
percent fill and 60 percent spare
14.
How
will you inspect a cable tray and vertical drop-down cable tray?
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
will check the cable tray size used as per IFC drawing and area classification
- I
will check the support location that no splice over the support
- I
will check the expansion joint location every 18 meters.
- I
will check the expansion gap shall be based on a temperature.
- I
will check the guide and hold the clamp location
- I
will check the torque of the bolt connection splice plate
- I
will check the bolt connection at the expansion plate using a special nut with
full tightness and with a half-turn back.
- I
will check grounding bonding at the expansion plate location, Horizontal
Adjustable Splice location, Discontinuous location, and Vertical adjustable
splice plate.
- I
will check the cable tray grounding from the grip with an interval of 25
meters.
- I
will check the end of the cable tray must have an end plate
- For
vertical the clamp must be bolted on the tray
15.
Tell
me about cable trays and what is the type of cable trays
- Cable tray material shall be copper-free
aluminum (aluminum with a maximum of 0.4% copper), or fiberglass. For offshore
applications, cable tray material shall be fiberglass. For indoor air-conditioned
areas galvanized carbon steel is allowed. Cable trays shall be of the ladder
(two side-rail) type
- Cable
Ladders, Single rail cable tray, Solid bottom cable tray, Trough (Ventilated
cable tray), Wire mesh cable tray, and Channel cable tray.
16.
What
are the cable tray fittings
- Horizontal
elbow, Horizontal tee, horizontal wye, horizontal cross, right & left
reducer, vertical elbow, vertical tee, Splice plates, and expansion plate,
Horizontal & Vertical Adjustable Splice.
17.
What
type of cable tray clamp and fittings do you need to install in a straight-line
cable tray?
- For
the straight line section only splice and expansion plate and the clamp is
guide clamp and hold clamp
18.
Cable
tray expansion joint distance and temperature
- In
reference to the temperature as per Nema VE2 with a temperature of 10 Celsius
with a gap of 9.5mm
19.
Tell
us about your experiences with GIS.
- Based
on the QCI experience
20.
What
are the area classifications?
- Class-1
Zone-0 -
- Class-1
Zone-1 –
- Class
1 Zone 2 -
21.
What
are the Battery room requirements
- BR
floor shall be reinforced concrete floor finishes shall be electrolyte-resistant
antistatic and
slip-resistant ceramic or porcelain floor tiles laid to slopes towards recessed
floor drains.
- Floor-to-wall transition/ Wall skirting/
Baseboard shall be made of 90 deg. coved wall skirting tiles with a height of
100mm on each wall.
- Walls
shall be finished with acid-resistant wall tiles starting at 100 mm above the finished
floor level. Acid-resistant
paint from the top of tiles to the soffit ceiling.
- Lighting fixtures
shall enclosed
and gasket (i.e., vapor-tight) corrosion-resistant
- Lighting
illumination shall be shall be 300 lux and emergency of 100 lux.
- Battery room doors shall open outward
fitted with door
closers and anti-panic (quick-release, quick-opening) hardware
- Emergency eyewash facilities shall be provided
- A dry type chemical fire extinguisher shall be
installed on the outside of the battery room.
- Cabinets or racks shall be provided in the
battery room for storing maintenance tools and safety equipment.
- Lead acid batteries shall not be mounted in
the same room together with nickel-cadmium batteries, and vice versa.
- Temperature in a room that contains batteries
shall not exceed 25°C.
- Lighting fixtures shall be installed at least
300 mm below the finished ceiling.
22.
How
much is the enclosure size of the required drain breather and what is the type
of drain breather
- 2000
cm3 enclosure size and type 316 stainless steel.
23.
What
is INCR, what are the contents of INCR and what are the critical INCR you
issued from your previous project
- INCR
is the internal none non-conformance report and is the tool of the QC inspector
to report any non-conformance or violation found during site surveillance or
pre-inspection activity.
Another question from QCI
- Tell me about yourself
- QCI Introduction and previous experience
2. Tell me about cable trays
- Cable tray material shall be copper-free
aluminum (aluminum with a maximum of 0.4% copper), or fiberglass. For offshore
applications, cable tray material shall be fiberglass. For indoor air-conditioned
areas galvanized carbon steel is allowed. Cable trays shall be of the ladder
(two side-rail) type
3. What are the fittings
- Horizontal
elbow, Horizontal tee, horizontal wye, horizontal cross, right & left
reducer, vertical elbow, vertical tee, Splice plates, and expansion plate,
Horizontal & Vertical Adjustable Splice.
4. Tell me about substations and their requirements
- Substation as any assemblage of electrical
equipment which includes a power transformer, switchgear, control gear, Battery
charger, Dry transformer, power & lighting panel, PSA, and annunciator.
-
Substation
buildings shall have smoke detection systems and fire stops
- Substation buildings shall be provided with
one exit door every 15 meters in the long wall opposite the transformer yard
side.
- Passageways shall have an unobstructed width
of 1.12 meters and shall provide a minimum 2.3 meter headroom.
- The elevation of the bottom of the lowest
interior cable tray shall be a minimum of 2.67 meters above the main substation
floor.
- Substation service entrance and branch circuit
feeders’ conductors other than grounding conductors shall enter or exit through
the building walls, and enter the equipment from the top
- Maximum substation building length and width
shall be limited to 75 and 15 meters
- Emergency illuminated exit signs shall be
provided in the substation
- Duplex convenience outlets shall be provided
throughout the substation building. A minimum of one outlet shall be provided
for each 6 meters of wall space at 1 meter above the floor.
-
Underneath
switchgear and control
gear leveling steel beams or
channels.
- The floor shall be horizontal in both planes
with a maximum surface height variation of less than 5 mm per 3 meters.
- Substation buildings shall have a minimum
2-hour fire rating
- Substation buildings shall have telephone and
data communications.
5. Direct buried cables requirements
- 600V and below – 610mm,
over 600V to 35kV – 920mm, over 35kV – 1070mm
6. Direct buried conduits requirements
- 600V and below – 460mm,
over 600V to 35kV – 610mm, over 35kV – 760mm
7. Installation of switch racks - situational questions.
-
8. Power transformers and its requirements
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
we will inspect the foundation released by the Civil team
- I
we will check the distance for MV transformer from the Power Transformer to the
substation building has a fire rating is 6.1 meters or greater. If no fire
barrier or barrier fire rating is less than 1 hour greater than a minimum of
15.2 meters of clear space.
- I
we will check the distance for MV transformer from transformer to transformer 7.6 m (7,570 and
18,930 liters transformers) and 15.2 m (>18,930 liters transformers)
- Checked
the Transformer oil
containment and/ or drainage systems shall be provided for oil-filled equipment
containing more than 2,500 liters of oil.
- The crushed rock shall be uniformly graded
having a sieve size between 25 mm and 60 mm
- The steel grating mesh shall have a sieve size
of less than 25 mm.
- A sump shall be provided at a corner of the
pit for the collection of rainwater or oil
- Then
we will check the grounding connection must be two connections on the opposite
side
- We
will check the centering of the transformer.
- We
will check the stub-up conduit on the exact position on the termination box
9. Steel conduits and its type and uses
- RGS
conduit - can be used in non-hazardous and hazardous locations
- RGS
PVC coated conduit – Corrosive area and direct buried
-
EMT conduit – Can be used indoor
10. Requirement documents in schedule Q before starting cable trays.
- Quality Procedure
- IFC Drawing
- ITP and checklist
11. Cable trays installation requirements
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
will check the cable tray size used as per IFC drawing and area classification
- I
will check the support location that no splice over the support
- I
will check the expansion joint location every 18 meters.
- I
will check the expansion gap shall be based on a temperature.
- I
will check the guide and hold the clamp location
- I
will check the torque of the bolt connection splice plate
- I
will check the bolt connection at the expansion plate using a special nut with
full tightness and with a half-turn back.
- I
will check grounding bonding at the expansion plate location, Horizontal
Adjustable Splice location, Discontinuous location, and Vertical adjustable
splice plate.
- I
will check the cable tray grounding from the grip with an interval of 25
meters.
- I
will check the end of the cable tray must have an end plate
- For
vertical the clamp must be bolted on the tray
12. Installation requirements for PVC conduits
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
-
I will check all drawing is IFC drawing
- Trench shall be sand bedding
with sweet sand 150mm
- The trench shall free of
stone and rubbles
- PVC conduit connection
shall be used PVC solvent cement
- End of conduit shall be
used of end bells
- For duct bank Checked the PVC conduit materials and
fittings used are correct if the conduit is TC2 the fittings must be TC3
- For duct bank Checked
the conduit to form works that have a 75mm outside surface for concrete to any
conduit or reinforcing steel
- For duct bank Checked
the spacer intervals of 2.4 meters and conduit separation of 50 mm for 50.8 mm (2 inches)
conduits and larger, and 25 mm for 38.1 mm (1½ inch) conduits and smaller.
- For duct bank Checked
that the bell end was installed on the end of the conduit, rope and a blind or
plug must be installed to protect during concrete pouring.
- For duct bank Checked
the quantity of conduit as per drawing is correct with a minimum of two spare
ducts.
- For duct bank Need
to check proper anchoring of the conduit to avoid movement during concrete
pouring
13. Illumination level in Substations.
- 100 lux
14. Power transformers installation requirements
- First
need to check quality procedure is approved before starting the construction
activity
- I
will conduct a Kick-off meeting before start starting the construction activity
- I
will check all drawing is IFC drawing
- I
we will inspect the foundation released by the Civil team
- I
we will check the distance for MV transformer from the Power Transformer to the
substation building has a fire rating is 6.1 meters or greater. If no fire
barrier or barrier fire rating is less than 1 hour greater than a minimum of
15.2 meters of clear space.
- I
we will check the distance for MV transformer from transformer to transformer 7.6 m (7,570 and
18,930 liters transformers) and 15.2 m (>18,930 liters transformers)
- Checked
the Transformer oil
containment and/ or drainage systems shall be provided for oil-filled equipment
containing more than 2,500 liters of oil.
- The crushed rock shall be uniformly graded
having a sieve size between 25 mm and 60 mm
- The steel grating mesh shall have a sieve size
of less than 25 mm.
- A sump shall be provided at a corner of the
pit for the collection of rainwater or oil
- Then
we will check the grounding connection must be two connections on the opposite
side
- We
will check the centering of the transformer.
- We
will check the stub-up conduit on the exact position on the termination box
15. Requirement of groundings for LV and MV equipment
- Two grounding connection
16. Power transformer testing
- Winding
resistance per taps, Insulation resistance, Polarization Index, Turn ratio per
taps, Excitation, Tan Delta, Oil test, Buchholz relay test, Winding temperature
indication test, Oil temperature indicator test, cooling fan functional,
Protection functional test, Stability test.
17. What is INCR and its contents and what is the INCR that you issued
- INCR
is the internal none non-conformance report and is the tool of the QC inspector
to report any non-conformance or violation found during site surveillance or
pre-inspection activity.
Another Question from QCI
- Self-introduction
and previous projects
- Questions
regarding trench depth, depth in asphalt for PVC conduit, and depth of
conduit in normal area.
- Questions
regarding conduits, fill percentage, coating thickness, who to check in
field coated conduit, field threaded conduit requirements,
- Questions
regarding grounding, individual rods, substation grounding, transformer
grounding, structure grounding, etc.
- Questions
regarding enclosures, drain breather type, and what size of enclosures
using breather.
- Questions
regarding INCR, two recent INCR related to standard, RC, CA, CA.
- Questions
related to starting from cable laying to MV cable testing, integrity
testing, Hipot testing.
- Questions
related to starting from cable laying to EHV cable testing
- Transformer
testing
- Transformer
to substation distance
- Cable
tray questions, fiberglass cable tray, expansion joints, grounding for the
cable tray
- Gap
between telecom socket to electrical socket
- What
are the type of drawings name it?
Thanks : Source From Er. Vellakannu Ramu
