J.W. Dice Co. 151 Microhm Meter Milliohm Resistance Tester 1-10000 Range

J.W. Dice Co. 151 Microhm Meter Milliohm Resistance Tester 1-10000 Range

The J.W. Dice Company Model 151 is a DC microhm meter designed to measure very low resistances — in the microhm to milliohm range — using a four-terminal (Kelvin) connection method. The instrument sources a DC test current through the Coarse and Fine rheostat controls and reads the resulting voltage drop on a calibrated galvanometer scaled in microhms. A rotary Multiply By switch extends the effective measurement range from 1× up to 10,000×, giving a full span of approximately 0–750,000 microhms (0–750 milliohms). A second meter displays the DC test current in amperes, allowing the operator to set and confirm the correct current level per the operating instructions.

Specifications & What's Included

• Manufacturer: J.W. Dice Company, Englewood, NJ
• Model: 151 (also referenced as 151-S)
• Serial Number: 1576 (internal reference only)
• Measurement type: DC low resistance in microhms
• Microhm meter scale: 0–75 microhms (analog D'Arsonval/galvanometer movement, Dice branded)
• Multiply By switch positions: 1, 10, 100, 1,000, 10,000 — extends full-scale to 750,000 µΩ
• Ammeter: Weston movement, 0–15 Amperes DC
• Controls: Multiply By rotary range switch, Coarse rheostat, Fine rheostat, On/Off switch
• Terminals: Four banana jacks — Voltage (−/+) and Current (−/+) for 4-wire Kelvin measurement
• Operating position: Horizontal use only (per front-panel label)
• Enclosure: Portable wood carry case with metal corner hardware, hinges, and latches
• Operating instructions and schematic diagram printed on interior lid
• Calibration sticker on front panel: references calibration with 026A leads

Applications

Microhm meters like the J.W. Dice Model 151 are used wherever contact resistance, bond resistance, or winding resistance must be measured at very low ohmic values — tasks that a standard ohmmeter cannot resolve accurately. Typical applications include measuring the resistance of electrical contacts, switchgear, bus bars, transformer and motor windings, grounding bonds, and welded or bolted electrical joints. The four-terminal (Kelvin) connection method eliminates lead and contact resistance from the measurement, which is essential at the microhm level. Instruments of this design were widely used by utilities, industrial maintenance departments, and electrical testing laboratories from the mid-20th century onward, and this class of instrument remains in active service today for commissioning and maintenance of power equipment. The J.W. Dice Company of Englewood, NJ was a respected U.S. maker of precision low-resistance test instruments, and the Model 151 is a well-regarded example of mid-century American bench instrument construction.