Four-wire testing is useful because it excludes lead drop from the defined measurement zone, not because the instrument shows more decimals. Current injection, sense points, temperature and assembly state must stay fixed before micro-ohm or milliohm data can be compared across lots.
Define the measurement zone before attaching probes
Mark current terminals C1/C2 and potential terminals P1/P2 on the drawing or inspection plan. Put P1/P2 on opposite sides of the interface being evaluated so fixture, feed lead and unrelated conductor length are excluded. Establish separate datums for bolted joints, solder terminals and mating contacts.
Control current, polarity, temperature and assembly state
Use enough current for a stable signal without creating material self-heating during the reading. Record ambient and specimen temperature, torque, surface condition, settling time and instrument range; use reversed-polarity checks where thermoelectric offset may matter.
- Confirm the fixture with a shorting reference or known conductor
- Repeat removal and reclamping, then report average, spread and outlier handling
- Use identical points and assembly instructions before and after ageing, vibration or thermal cycling
Specify the method, not an isolated resistance number
An RFQ should state material, finish, contact structure, point diagram, test current, temperature, torque, sample size, instrument accuracy and decision rule. A connector test method does not create a universal limit for every busbar geometry; the project limit still belongs to the complete current path and rise validation.
Apply this guide to a project
Use product pages to identify the hardware family and the calculator for early estimates only. Acceptance depends on drawings, operating conditions and project tests.