Milli-Ohmmeters
A milliohm meter measures extremely low electrical resistance, often down to fractions of a micro-ohm, values far too small for a standard multimeter’s ohm function to read accurately. We stock handheld and benchtop milliohm and micro-ohm meters using four-wire Kelvin measurement, built for testing switch and circuit breaker contacts, weld joints, transformer windings, cable splices, and bonding connections. Below a few ohms, lead and contact resistance distorts a standard ohmmeter’s reading, which a dedicated milliohm meter is designed to correct.
A standard two-wire ohmmeter forces test current through the same leads it uses to measure voltage, so lead resistance gets folded into the reading and swamps the tiny resistance you’re actually trying to measure. A four-wire Kelvin setup separates the current-carrying leads from the voltage-sensing leads, canceling out lead and contact resistance so only the resistance of the device under test remains. High-current models push 10 to 200A through the connection, revealing weak joints a lower-current test would miss.
Types of Milli-Ohmmeters
Handheld portable milliohm meters offer four-wire Kelvin measurement in a field-ready package, suited to spot checks on cables, connections, and small components in the shop or on-site. Benchtop micro-ohmmeters deliver the highest resolution, down to fractions of a micro-ohm, for lab and quality control work where precision matters most. High-current DLRO (Digital Low Resistance Ohmmeter) or Ductor testers push 10 to 200A through switchgear, circuit breakers, and weld joints, revealing weak connections that only show up under real load current.
Common Applications
- Switch and circuit breaker contact resistance testing
- Weld joint and bond quality verification
- Transformer and motor winding resistance testing
- Cable splice and connection resistance checks
- Aircraft frame, rail, and pipeline bonding tests
Choosing the Right Milli-Ohmmeter
Match resolution to the smallest resistance you need to detect, fractions of a micro-ohm for precision lab work, milliohm resolution for general field testing. Choose a high-current DLRO when you need to verify a connection under realistic load conditions, such as switchgear or circuit breaker contacts. Every meter we carry is backed by manufacturer warranty support, and our team can help match test current, resolution, and portability to your application.
Not sure which milliohm meter fits your work? Contact our team — we can match resolution and test current to your testing needs.
Frequently Asked Questions
Why can’t a standard multimeter measure milliohms accurately?
A standard two-wire multimeter includes the resistance of its own test leads and contacts in the reading, which swamps the tiny resistance value you’re trying to measure below a few ohms.
What is four-wire Kelvin measurement?
It’s a technique that separates the current-carrying test leads from the voltage-sensing leads, canceling out lead and contact resistance so the meter reads only the resistance of the device under test.
What is a DLRO or Ductor tester?
It’s a high-current milliohm meter, typically 10 to 200A, used to test switchgear, circuit breaker contacts, and weld joints under a current level closer to real operating conditions.
What test current do I need for my application?
Lower current handheld meters suit general cable and component testing, while high-current DLRO testers are better suited to switchgear and circuit breaker contacts where connection quality under load matters most.