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Portable 3-Phase Watthour Meter Tester
SKU: WT1 Category:



Portable 3-Phase Watthour Meter Tester

All good things must come to an end!
2021/06/30 08:50:28
After careful consideration, we have decided to discontinue the manufacture and sale of the MT-1/NT3 meter tester by June 30th, 2021, with a last time buy on July 31st, 2021.
The standard warranty terms will be honored for all units shipped to date.  Active orders prior to the announced date will be honored according to the terms of that order, with regard to product availability, warranty, or support terms.
Probewell | Trade-in Program

If you own an older-generation Probewell product, you are automatically eligible for our trade-in program, meant to ensure that our ­­customers get all the benefits of our latest innovation by transitioning to an up-to-date version of the solution.

Trade in your older-generation Probewell tester and get an up to $1,000 discount on the purchase of any of our latest models.  

The MT-1/NT3 is an ideal tool for field-testing and periodic sampling of self-contained meters. No setup wiring is needed. A complete test is done within a few minutes!


The MT-1/NT3 can be set to test all 3 phases simultaneously in one step or set to do a full test consisting of the 3 phases simultaneously followed by each element separately.

Self-Contained Meters

An ideal testing solution for self-contained meters, the MT-1/NT3 also has reverse flow testing capability for net metering installations.


Uncompromised accuracy

Three built-in 50A current synthesizers (phantom load) simulate active and reactive load.

Its built-in single-phase Wh/VARh standard will offer you a typical NIST traceable accuracy of ±0.02%.

Easy Setup

Fast setup with no wiring and a dead-front design means your operation is quicker and safer.

Setting-up your test has never been easier.

Technical Specifications

Compatible Meters
Single-Phase 1S, 2S, 12S, 14S, 15S and 16S
Class 100, 200, 320
Test Socket
Input Voltage 100 – 600VAC
Line Frequency 58 – 62Hz
Power Consumption 75VA (maximum)
Circuit Breakers 3 x 1A (press-to-reset mechanism)
Current Synthesizers
Adjustable Current 1 to 50A
Phase Angle (Wh) Unity and 60° Lag
internal 3-phase Watthour Standard
Typical Accuracy ±0.02%
Guaranteed Accuracy ±0.05%
Operation Temperature -4° to 140°F (-20° to 60°C)
Storage Temperature -4° to 140°F (-20° to 60°C)
Physical Dimensions
Test Socket (Diam. x L) 6.9” x 7.7”
Remote Control 8.3” x 3.9” x 1″
Carrying Bag 11″ x 11″ x 8″
Test Socket 5.7 lb
Remote Control 0.6 lb
Carrying Bag 8.7 lb
Parts and Labor 2-years limited***
Carrying bag Update cable
User’s manual WTDataOne Software
Quick Start Guide 2 Removable Twist Tabs
Calibration report Remote Control

***Only applicable to units shipped to Canada or USA. 1-year warranty for other countries.

Often used with these accessories