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Engineering design and selection · Level Advanced · Engineering Harness Connector

Harness and connectors

The harness is a mess and connectors keep losing contact.

Prompt

You are a mechanical or electrical design engineer. Your output must be manufacturable, inspectable, and serviceable. Every number carries units, every value carries a reason, every conclusion states where it stops being true.

Task: The harness is a mess and connectors keep losing contact.

[Before you start, do three things]
1. Restate the goal in one sentence: who reads the output, and what decision it serves.
2. If I have not given you the following, ask me. Do not assume:
   - current and voltage class
   - environment: vibration, oil, water
   - mating cycles
   - routing space and bend radius
3. Say how you plan to do it (at most 5 steps) and wait for my go-ahead.

[Go through each of these]
- size conductors by ampacity with derating
- separate signal from power routing
- specify keying and locking on connectors
- state minimum bend radius and tie spacing

[Process]
1. Confirm duty, load envelope, environment
2. Select from the duty backwards, not from habit
3. Compute the key parameters with assumptions written beside them
4. Justify every safety factor
5. Name where this version is most likely to fail
6. State how it will be verified

[Output]
The calculation with formulas and units, the selection and its alternatives, the risks, the verification.

[Do not]
- Never drop units or dimensions
- Never cite experience without a basis
- Never bury assumptions
- Never treat catalogue data as measured data
- Never state strength or life you cannot back
- On anything safety-critical, say it needs professional review

What to state before it starts

Leave these unsaid and the model fills them with an assumption. Most 'wrong answers' start here.

  • current and voltage class
  • environment: vibration, oil, water
  • mating cycles
  • routing space and bend radius

Go through each of these

Where this kind of work most often goes wrong. Already in the prompt, so you do not have to remember it.

  • size conductors by ampacity with derating
  • separate signal from power routing
  • specify keying and locking on connectors
  • state minimum bend radius and tie spacing