CIT Cable and Wire Harness Assembly Requirements 3 — Questions and Answers
Question 1: According to IPC/WHMA-A-620, what is the acceptable nick depth in wire insulation for a Class 3 assembly?
- No nicks are acceptable (Correct answer)
- Up to 10% of insulation wall thickness
- Up to 25% of insulation wall thickness
- Up to 50% of insulation wall thickness
Correct answer: No nicks are acceptable
Class 3 assemblies require zero nicks in wire insulation because any damage could compromise reliability in high-performance applications.
Question 2: When a wire harness drawing specifies 'Shield Grounded at One End Only,' what assembly defect would result from grounding both ends?
- Reduced mechanical strength of the shield
- Creation of a ground loop that introduces noise (Correct answer)
- Corrosion of the shield braid at both ends
- Increased cable weight beyond specification
Correct answer: Creation of a ground loop that introduces noise
Grounding a shield at both ends creates a ground loop, which can act as an antenna and introduce electromagnetic interference into sensitive signals.
Question 3: What is the correct method for securing a wire harness to a connector backshell during assembly?
- Using any available adhesive to bond the harness jacket to the backshell
- Following the strain relief design specified in the engineering drawing (Correct answer)
- Wrapping the junction with electrical tape
- Using cable ties tightened directly over the conductors
Correct answer: Following the strain relief design specified in the engineering drawing
The engineering drawing specifies the approved strain relief method, which must be followed to ensure proper mechanical protection and meet design intent.
Question 4: When assembling a high-voltage cable harness, what minimum documentation must accompany each assembly?
- Only the bill of materials
- Assembly drawing, test report, and material certifications (Correct answer)
- Customer purchase order only
- A handwritten note from the assembler
Correct answer: Assembly drawing, test report, and material certifications
High-voltage assemblies require assembly drawings for construction verification, test reports confirming electrical performance, and material certifications to confirm approved materials were used.
Question 5: In a wire harness, when is it acceptable to use a wire nut (wire connector) as a splice method?
- Always acceptable for any harness application
- Only when specified on the engineering drawing (Correct answer)
- Acceptable for low-current circuits only
- Acceptable as a temporary repair method
Correct answer: Only when specified on the engineering drawing
Per IPC/WHMA-A-620, wire nuts are only acceptable when specifically called out in the engineering documentation; they are not a default acceptable splice method.
Question 6: What is the purpose of a harness form board (layout board) during wire harness assembly?
- To test the electrical continuity of completed harnesses
- To provide a dimensional template ensuring repeatable harness geometry (Correct answer)
- To hold connectors during crimping operations
- To store completed harnesses awaiting shipment
Correct answer: To provide a dimensional template ensuring repeatable harness geometry
A form board is a full-scale drawing or fixture on which wires are routed and secured during assembly to ensure consistent harness dimensions and breakout locations.
Question 7: Which wire color is universally reserved for ground (chassis ground) per ANSI/EIA wiring color code standards in US-manufactured equipment?
- Red
- White
- Green or bare (Correct answer)
- Blue
Correct answer: Green or bare
In US electrical standards, green or bare (uninsulated) conductors are reserved exclusively for protective earth/chassis ground connections.
CIT Cable and Wire Harness Assembly Requirements 3
According to IPC/WHMA-A-620, what is the acceptable nick depth in wire insulation for a Class 3 assembly?