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E&I QC Inspector Interview Questions
1. Briefly explain the duties of a QC E&I Inspector?
Ans. Responsible for the specific implementation of Quality Plan)or E & I in accordance with the clients issued IFC drawings, specifications, Procedures, Codes and Standards. Inspector shall conduct for inspection and necessary documentation during the construction phase of its main activity covered under this E / I works. If the intervention of the client QC inspector are required to witness and inspection event for test as per Inspection and Test Plan.
Inspector/Supervisor shall notify them through RFI for their presence and involvement of the inspection. The results of the inspection witness shall be certified and recorded, major deficiencies found during the inspection, Raised NCR to the concern construction production unit who will take necessary and corrective action.
2. What are the main documents a QC Inspector shall have a reference in order to perform QC duties properly and effectively during inspection?
Ans. Client Issued for Construction (IFC) drawings, Inspection and Test Plan, Project Quality Plan, Client Engineering Standards, Specifications, Codes and Procedures.
3. To whom should a QC Inspector directly the report? State the basic reason.
Ans. Report to the respective Project QC Managers or QC Supervisor to inform them the latest development/progress of field or vendor’s inspection as closed coordination and communication pertaining to all QA/QC works.
4. Define the steps a QC Inspector should follow to check inspect quality of electrical equipment, such as transformer, etc. from receiving of materials and to testing?
Ans. To be checked in accordance to Purchase Order, material specifications, Certificate of compliance & Material Test Certificates & data’s and IFC drawings.
5. What are the appropriate steps a QC Inspector should execute upon identifying significant deviation or violation from quality requirements/standards?
Ans. Report immediately to the /QC Manager/Supervisor or Raise the Non-Conformance Report (NCR) to the respective and cocerned production unit which will take necessary corrective dction.
6. Explain work procedure a QC Inspector should follow prior and during the Testing of specific equipment?
Ans. implementation of specific Quality Plan and Inspection Plan in accordance with the client issued IFC drawings, specifications, procedures, industry codes and standards.
Inspector shall conduct inspection and necessary documentation during the construction phase of each main activity covered under this E & I works. If the intervention of the client QC inspectors are required to witness and inspection events or test as per Inspection and
Test Plan. Inspector/ Supervisor shall notify them through RFI for their presence and involvement on the inspection. The result of the inspection shall be certified and recorded, major deficiency found during the inspection, raise the NCR to the concerned production
unit who will take necessary and corrective action.
Part II (Technical per NEC, SAES & IEEE):
1. What is the maximum percentage of cross section a conduit can be filled containing three (3) or more wires?
Ans. Per NEC 501-5(5) © (6) – the wires shall be fill not exceed 25% of the cross-sectional area of the conduit size.
2. What is PVC in cable insulation an abbreviation for?
Ans. Poly-Vinyl-Chloride (PVC).
3. what is the purpose of drain/shield in instrumentation wires?
Ans. To minimized electrostatic noise to prevent unnecessary distribution of signals.
4. As per Aramco Standards, what is minimum separation between low voltage power cables and instrumentation cables in cable trays?
Ans. minimum of 50mm (refer to NEC)
5. Per NEC what is the maximum distance between supports for 2-inch rigid steel conduit?
Ans. a) for Horizontal – 3 meter (10 ft.)
b) for Vertical – 6 meter (20 ft.)
6. Per Aramco Standard, what is the minimum size of grounding grid conductor?
Ans. per SAES-P-111 – minimum of 70mm2 (2/0 AWG) / for stranded bare copper cable-4/0kcmil
7. Per NEC, what would be the size of equipment grounding copper conductor for equipment protected by over current device rated 600 Amperes?
Ans. 1/0 AWG / 50mm2 per NFPA art. 250.122
8. Per NEC, what would be the size of grounding electrode copper conductor for alternating current system having largest service conductor sized 350 kcmi!?
Ans. Per NFPA art. 250.122 minimum of 120mm2 (4/0 AWG) / 350 kcmil
9. How the grounding conductor would be connected to underground grounding grid?
Ans. a) by Thermite Welding
b) by Approved Mechanical Compression
10. What do the following letters denote on electrical equipment and explain the markings?
Ans. Exd-Equipment Standard Symbols
b) IIB – Gas Classification Group
c) T5 – Temperature Classification Group
11. On electrical equipment or material being used in hazardous area, you may see the letter UL or C.S.A., listed what is these abbreviations or meaning stand for?
Ans. a) Underwriter Laboratories (UL)
b) Canadian Standard Association (CSA)
12. NEC, what are the instances where seals fittings are needed?
Ans. In Hazardous Location· a) Classified Location Class 1; Zone 0, 1 & 2
b) Unclassified Locations, Class 1, Div.1 & 2
Class II, Div. 2
Class Ill, Wet Location
13. How many degrees bend permitted in a conduit run? Also the max. number of bends.
Ans. In terms of degrees shall not be exceed more than 270 degrees to prevent hard pulling of cables and cable damage
14. as per NEC, what is the minimum number of conduit threads should be engaged at hazardous locations?
Ans. Per NEC art. 501-4 (A) – five (5) full threads shall be engaged
15. What is the color code of grounding, neutral and phase conductor?
Ans. a) Phase conductor is black,
b) Neutral is White,
c) Grounding is Green
16. What is minimum temperature rating required for low voltage wires?
Ans. 90°C dry, 75°C wet.
17. Name the type of electrical tests instrument equipment required for testing to the following cables.
Answer: Medium voltage power cables- Megger Test, DC High Potential Test.
b) Cathodic protection cables- Holiday Test.
C) Low voltage cables – Resistance Test & Megger Test
d) Instrument cables – Megger Test, Continuity Test.
19) Name some of the tests required for testing of the following Electrical Equipment
Ans.
a) Oil type transformers – Winding Test, Turns Ratio Test and Transformer Oil tester
b) Electrical Motors –Winding Test, Resistance Test, Megger Test and Phase rotation tester
c) Batteries- Specific Gravity (G) Test, Voltage Current Test.
d) Circuit Breakers – Primary Current inspection Test, Megger Test and Ductor Test.
20) What is the NEMA rating for electrical enclosures installed in the following environments?
Ans. Indoor – NEMA 1
Outdoor – NEMA Type 3 or 4
Corrosive Environment – NEMA 4X
21. How many divisions and groups a Class I atmospheric hazards is divided & grouped? What are the locations covered by each division?
Ans. Class 1, Zone O – flammable gases or vapor are present continuously.
Class 1, Zone 1 – flammable gases or vapor gases likely to exist under normal operation condition.
Class 1, Zone 2- flammable gases or vapor are not likely to occur in normal operational or short period.
22) Define following for enclosures containing arching electrical device and installed in hazardous area?
Ans. a) Type – Class 1, Zone O – in w/c ignitable concentration of flammable gases or vapor are present continuously (flammable mixture present 10%).
b) Safety Factor – Class 1, Zone 1 – in w/c ignitable concentration flammable gases or vapor are likely to exist under normal operation condition (flammable mixture present 0.1 to 10%).
c) Flame tight – Class 1, Zone 2 – in w/c ignitable concentration of flammable gases or vapor are not likely to occur in normal operation and if they do occur they exist only for a short period (flammable mixture present 0.01 to 0.1 % -unclassified location flammable mixture present .01%).
23) Per Aramco Standard, what is the maximum resistance value permitted for grounding system at industrial area?
Ans. Not Greater Than 0.1 ohm. To be verify ..
24) How do you determine the correct size equipment ground conductor for a 1600 amp. over current device?
Ans. Per NEC minimum of 120mm2 (#: 4/0 AWG). To be verify
25) What is the allowable percentage (free space) of cross section e conduit can be filled?
Ans. Per NEC art. 501-5(5) (C) (6) – shall not exceed 25% of the cross-sectional area of the conduit
26. What is a T stands for to equipment installation in Hazardous area?
Ans. Per NEC art. 500.8 – Temperature Classification (“T”) – Class, I & II.
27) Can you use lighting fixture installation as a raceway?
Ans. No … lighting fixture shall be used only to protect light bulb etc.
28. Where are conduit supports required for rigid steel?
Ans. at a maximum 3M (1 Oft.) for Horizontal & 6M (20 ft.) for vertical.
29. Where are seal fittings required?
Ans. Hazardous Locations Classification I, II & Ill.
30. What are all sources of information used to ensure specific electrical installation meets all requirements?
NEC – National Electrical Code
NFPA- National Fire Protection Authority
NEMA -National Electrical Manufacturer’s Association
NETA – National Electrical Testing Association
31) What will he do when he finds a violation of any of the above?
Ans. Report immediately to the respective QA/QC manager / Supervisor or Raised Non Conformance Report (NCR) to the respective and concern production unit who will take necessary and corrective action.
32) Discuss electrical area classification (from general to details)