A potential lossy area in electrical circuits (both for power and signal) is at the contact points. Poor mating, contaminated surfaces, poor crimping, and/or damaged plating can all add resistance to the circuit. A means of assessing this impact is by measuring the contact resistance. Contact resistance refers to the electrical resistance that can be attributed to the contacting interfaces of electrical leads and connections. In circuit design, the expectation is for most of the resistance to be at the circuit load. However, high contract resistance can cause heating at connectors and impact the functionality of connected equipment due to under voltage conditions at the circuit load.
The contact resistance is typically identified in contact and connector specifications. For example, MIL-DTL-26482 compliant connectors must have contact resistance for size 20 is less than 30mΩ less than 20mΩ for size 14 contacts.