EMC pre-compliance checklist (before you book the lab)

Most EMC failures are predictable. Use this checklist to catch common issues early—when fixes are still cheap.

1) Define the test configuration

• List all cables, accessories, and peripherals (type + length) that will be used in testing.
• Define “worst-case” operating modes (max load, PWM, motors, radios, switching states).
• Confirm power sources used in test (internal/external supply, grounding/PE assumptions).

2) Grounding and bonding (system-level)

• Write down your grounding strategy: what bonds to chassis/PE and where.
• Ensure bonding points are intentional (no “painted metal = floating ground” surprises).
• Verify low-impedance bonds for key points (enclosure seams, brackets, cabinet panels).

3) Cable routing & shield termination

• Separate noisy cables (motor/drive, switching power) from sensitive cables (I/O, sensors, comms).
• Define shield termination rules (both ends vs one end) and apply them consistently.
• Avoid long shield “pigtails” where possible (they kill shielding performance).

4) Layout & filtering

• Confirm clear return paths for high-speed signals and switching currents.
• Place I/O filtering at the boundary (connector side), not deep inside the PCB.
• Keep filter grounds short, wide, and low impedance.

5) Enclosure realities

• Assess seams, vents, displays, and cutouts as EMI leakage points.
• Validate conductive continuity across panels/doors (gaskets/coatings if needed).
• Check that mounting and cable entry points don’t break shielding/bonding.

Quick “go/no-go” before formal lab time

• Final-ish harness and cables (not dev jumpers).
• Worst-case modes scripted and repeatable.
• Grounding and shielding rules documented so nobody improvises.
• Pre-check run confirms no obvious issues before booking expensive time.