Digital low-resistance ohmmeter testing of breaker contacts, bus joints and bolted connections — the number behind the hot spot. Serving Boise, Meridian, Nampa, Caldwell, Eagle, Star and all of Idaho.
A digital low-resistance ohmmeter (DLRO) — also called a micro-ohmmeter or ductor — measures resistance in micro-ohms across breaker contacts, bus joints, bolted connections and splices. It passes a high DC test current through the joint and reads the voltage drop with a four-wire connection, so test-lead resistance does not skew the result.
A connection that has loosened, oxidized or pitted generates heat under load. That heat is what a thermal camera catches on a good day — and what starts a fire on a bad one. DLRO testing finds the problem directly, with a number you can trend and compare phase to phase.
Results are compared with similar phases and the manufacturer's data where available. Anything out of range is flagged for cleaning, re-torquing, repair or replacement.
Infrared scanning finds a hot connection while the system is running. DLRO testing confirms the cause and measures the repair during a shutdown. Torque verification, cleaning and breaker exercising often go in the same maintenance window, so the same outage fixes the problem and proves it is fixed.
See also: infrared thermography, insulation resistance testing and the full testing & inspection overview.
DLRO stands for digital low-resistance ohmmeter, also called a micro-ohmmeter or ductor. It sends a high DC test current through a connection and measures the tiny voltage drop to calculate resistance in micro-ohms.
Worn or burned breaker contacts, loose or corroded bolted bus joints, and bad terminations. These high-resistance spots create heat under load and are a common cause of switchgear failures.
Yes. DLRO testing is performed on de-energized, locked-out and verified-dead equipment, so it is scheduled in a planned maintenance window.
Yes. Ductor testing and micro-ohm testing are other names for low-resistance contact and joint measurement.
Yes, and we recommend it. Infrared finds hot spots while the equipment is running; DLRO testing during the shutdown confirms the cause and verifies the repair.
Start with a no-cost, no-obligation survey: we'll walk your electrical system, give you a written proposal for your testing program, and include the replacement cost of your electrical distribution — so you know exactly what's at stake.
