LOM-510A Micro-Ohmmeter

  • 1 μΩ resolution, 4½ digits
  • Range: 1 μΩ - 200 Ω
  • 0.02% basic accuracy
  • Costs around 50% less then its peer instruments
Priced at

The LOM-510A Micro-Ohmmeter is a dedicated low resistance meter, useful wherever there is a need for measuring very low values of resistance. The LOM-510A is far superior, to general purpose and even higher end bench multimeters that utilize 4 terminal connections, when measuring resistances below 1 ohm.

The Micro-Ohmmeter has 4½ digits, 0.02% basic accuracy and 1 μΩ resolution. The 4-terminal kelvin measurement connection minimizes lead resistance errors and 80 dB of ac noise rejection provides rock-steady readings even in noisy locations. The micro-ohmmeter comes with rugged 4-terminal test clips and a large selection of optional probes, clips and fixtures allowing attachment to any low-resistance unknown.

The highest range of 200 ohms full scale on the LOM-510A is close to the lowest range on general purpose 4 1/2 digit multimeters and ohmmeters. Generally, the measurement range of the Model 510A begins where the general purpose instruments end.

A significant feature of the LOM-510A Micro-ohmmeter is the three separate component drive modes. The combination of good basic accuracy and selectable drive modes makes the LOM-510A a highly useful and accurate resistance measuring instrument. The Switched DC Mode totally eliminates the effects of thermal EMF, a very important source of error. The Continuous DC Mode is required when measuring the resistance of highly inductive components such as transformers. The Pulsed Mode is important when measuring heat sensitive components such as thermistors.

In addition, the Model 510A can perform “dry circuit” measurements. This measurement mode is useful when measuring the contact resistance of low level switches. Several MIL specs require “dry circuit” measurements of certain switch types.

LOM-510A Micro-Ohmmeter Applications:

  • Fuse Testing
  • Switch or Relay Contact Resistance Measurement
  • Electrical Motor Winding Resistance
  • Cable Resistance


(See datasheet for full specifications)

Min Resistance
Range (Full Scale)
Max Dissipation
1 μΩ
19.999 mΩ
1 A
20 mW
5.0 mW
10 μΩ
199.99 mΩ
0.1 A
2.0 mW
.50 mW
100 μΩ
1.9999 Ω
10 mA
.2 mW
.05 mW
1 mΩ
19.999 Ω
1 mA
.02 mW
5  μW
10 mΩ
199.99 Ω
0.1 mA
.002 mW
0.5  μW


 (SW)(Switched dc)   DC(Continuous dc)   Pulsed Mode 
 0.02% + 2 counts +2 μΩ   0.04% + 2 counts + 2 μΩ (Typical)   0.02% + 4 counts + 2 μΩ