The WT3122 Electromagnetic Radiation Tester from Wintact is a tool for detecting and measuring electric and magnetic fields. It is a compact handheld device that you can operate with one hand. The device has a large display and only three pushbuttons: On/Off, Average/Peak value (AVG/VPP) and Unit selection. There is also an LED. A rechargeable battery powers the device, a micro-USB cable to charge it is included in the box.

Specifications of the WT3122

A label on its back lists the specifications of the WT3122. Electric fields are measured in V/m, magnetic fields in either µT (microtesla) or mG (milligauss). The electric field strength range is from 1 V/m to 1999 V/m with a precision of 1 V/m. The magnetic field strength range is 0.01 µT to 99.99 µT (0.01 µT precision) or 0.1 mG to 999.9 mG (0.1 mG precision).

Alarm function

As one gathers from the user manual, the radiation tester is intended for people who worry about the effects of electromagnetic radiation on their health. As such, the device does not just measure field strengths, it also has an alarm that sounds when a field strength is above the predefined threshold of 40 V/m, 0.4 µT or 4 mG. This value is fixed and cannot be set by the user.
wintact wt3122 alarm
The display turns red when the alarm is triggered.

When the alarm is triggered, the normally blue display turns red, and a buzzer starts beeping. Also, the red LED begins to flash. You can deactivate the buzzer by holding down the AVG/VPP button for a few seconds. Repeating this procedure will turn the buzzer back on.

The WT3122 is a Thermometer too!

Not mentioned anywhere is that the WT3122 is also a thermometer. The temperature is shown in the middle of the display in between the electric and magnetic field strength values. Holding down the Unit button for a few seconds lets you choose degrees Celsius or Fahrenheit.

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First Power On

The radiation tester comes precharged, so you can switch it on straight out of the box. When I did this, the alarm went off immediately, with the device beeping and flashing red. As I didn’t expect this at all, my first reaction was to drop it or throw it away. Luckily, my strong nerves quickly took back control of myself, which saved the device from premature destruction. As I know now, the alarm is always on.

A few seconds after placing the WT3122 on my desk, the alarm switched off and the screen turned blue. The readings returned to zero (except for the temperature). This gave me the opportunity to calmly study the display.

The Display of the WT3122

Electric- and magnetic field strengths are measured at the same time and are shown with large digits. A bar graph shows where they sit in the full range. When a value is below the alarm level, the display shows ‘Good’ for that value; when the value is above the threshold, it shows ‘Warning’ (besides turning red and the buzzer beeping and the LED flashing). The bar graph has 14 elements, the alarm threshold is on the second.
wintact wt3122 transmission tower ground
Not holding the tester in your hand has an important influence on the electric field strength reading (upper value of 0.00 V/m). The magnetic field strength (bottom value of 5.14 µT) remains unaffected.

Your Body is a Capacitor

As soon as I moved my hand close to the device, the alarm was triggered on the E-field. Simply by holding the device I could obtain values of over 450 V/m depending on how firmly I clamped it. Keeping my hand out of the way and wiggling the end of a plugged-in phone charger cable in front of the tester (where the sensor is), the E-field showed values of over 250 V/m. Pointing it at a power outlet, I measured some 450 V/m.

Tesla meter?

During these experiments, the magnetic field (H-field) stayed at zero all the time. I therefore placed a magnet in front of it. This triggered the H-field alarm, but only for a few seconds only, as the value dropped back to zero. A magnet produces a static (DC) field, so maybe the device is intended for AC fields? To try this, I plugged a coiled-up 40-meter extension cord reel into a power outlet and a thermal paint stripper to the cord’s other end. Switching on the heat gun produced a more or less stable reading on the H-field of over 13 µT (130 mG).

Point it Properly

The obtained H-field value depends a lot on the pointing direction. With the heat gun powered from a split-conductor cable (i.e. the conductors are individually accessible to allow a current clamp to take current measurements on the phase or neutral of e.g. a household appliance) I managed to get H-field values of over 50 µT (500 mG). During all these experiments, the E-field fluctuated between 350 and 450 V/m.

Cell Tower

wintact wt3122 cell tower
A small magnetic field of 0.38  µT is detected at the base of this cell tower.
As the WT3122 is intended for people interested in environmental and health security matters, I decided to take it out to a cell phone tower and a high-voltage transmission tower, as these tend to be causes of worries for many people.

To my surprise, sort of, the cell tower only produced a magnetic field reading. The E-field showed almost zero. Right at the base of the tower, I measured around 0.40 µT (40 mG), a value that remained stable but changed when the tester was moved around.

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Transmission Lines

At some fifty meters distance from a HV transmission tower, right under the conductors with the tester in my hand, the device showed an H-field of approx. 5.7 µT (570 mG) and an E-field of 875 V/m. Placing the tester on the ground so that I no longer touched it, the E-field reading dropped to zero, but the H-field reading remained.


Note that pressing the Power button briefly during measurements toggles Hold mode on and off, so you can write down the field strength values without needing to remember them. Pressing Power for a few seconds switches the device off. Note that it also switches off automatically after about five minutes.

wintact wt3122 transmission tower
A high-voltage transmission line produces a strong magnetic field (bottom value of 5.77 µT).


The WT3122 Electromagnetic Radiation Tester from Wintact is not a lab instrument for measuring electric and magnetic field strengths with any precision. It is also unsuitable for locating electric wiring in a dry wall. But that’s okay, as it doesn’t claim to be this, either. The WT3122 is simply an electromagnetic field strength presence indicator.

The device is easy to use as it doesn’t have any configuration settings or usage options. Switch it on and away you go. However, it is sensitive to how it is being held, placed, and oriented. So, simply pointing it towards a suspicious source is not enough, it must be moved around (it) to find the ‘real’ values. The question that remains then is: What are the real values? (And what to do with them?)