What is the typical range for acceptable connector contact resistance?

What is the typical range for acceptable connector contact resistance?

• A. A few milli-ohms to a few tens of milli-ohms
• B. Several ohms
• C. Several kilo-ohms
• D. Zero ohms

Answer: (A)

Connector contact resistance should be very small because it adds resistance in series with the circuit path, affecting both voltage delivery and heating. In practice, an acceptable contact resistance is typically in the milli-ohm range, from a few milliohms up to a few tens of milliohms. This keeps voltage drop low at normal currents and minimizes I^2R heating in the connector itself. For example, at 5 A, 10 mΩ would produce a 0.05 V drop and about 0.25 W of heat, which is usually acceptable for a single contact in many assemblies. If the resistance were several ohms, the same current could drop multiple volts and dissipate watts of heat, degrading performance or causing damage. Several kilo-ohms would essentially prevent current flow. While zero resistance would be ideal, real connectors always have some finite contact resistance due to surface conditions, contact pressure, and materials, so the goal is a very small but finite value rather than an exact zero.

Connector contact resistance should be very small because it adds resistance in series with the circuit path, affecting both voltage delivery and heating. In practice, an acceptable contact resistance is typically in the milli-ohm range, from a few milliohms up to a few tens of milliohms. This keeps voltage drop low at normal currents and minimizes I^2R heating in the connector itself. For example, at 5 A, 10 mΩ would produce a 0.05 V drop and about 0.25 W of heat, which is usually acceptable for a single contact in many assemblies. If the resistance were several ohms, the same current could drop multiple volts and dissipate watts of heat, degrading performance or causing damage. Several kilo-ohms would essentially prevent current flow. While zero resistance would be ideal, real connectors always have some finite contact resistance due to surface conditions, contact pressure, and materials, so the goal is a very small but finite value rather than an exact zero.