Comparison of the hidden wiring detector Bosch GMS 100 and MD120

Hidden wiring Detector is an irreplaceable thing during repair. Of Course, you can save on this tool, but often such savings are spent hours of time to recover damaged wiring.

In The article I compare the quality of the voltage wire definition for two variants of the hidden wiring deactors. MD120 I have purchased on Aliexpress. Do not specify a specific store, and I give a link to search by Aliexpress, because when buying successfully hit the share and the device came out a little cheaper.

MD120 Hidden wiring Detector is present on Aliexpress under different names of manufacturers. In Russia It is sold as ADA Instruments Wall Scanner 120. At 100% I can not say that it is still the same MD120, but with a probability of 95%-it is.

The Device is positioned as an analogue of professional Bosch GMS 120 Professional. Immediately Note, the devices are different. With a difference of 400 rub. I would ODOZNACHNO took Bosch. Even the Junior model Bosch GMS 100 M Professional works more stable.

Characteristic Bosch GMS 100 M Bosch GMS 120 MD120
Electrical wiring Detection Depth
50 mm50 mm50 mm
Depth of detection of ferrous metals
100 mm120 mm120 mm
Detection Depth of non-ferrous metals80 mm80 mm
80 mm
Depth of detection of wooden structures No38 m38 mm
Color IndicationHaveHave Have
Time of work
5 h5 h
Automatic shutdown
5 min.5 min.5 min.
Sound Indication
HaveHave Have
Dust and Splash ProtectionIP54IP54 IP54???
Battery Type
Crown (6LR61/6LF22) Crown (6LR61/6LF22) Crown (6LR61/6LF22)
Size, HVHG85x197x3095 x 197 x 3595 x 220 x 35
Weight of the device
270 g270 g 270 g

According to the TTH device with the number 120 similar. Moreover, visually they are also one in one, only the color of the case is different. Unfortunately, I did not have under the hands of GMS120, so on the comparative photo proportions approximate.

Comparison of Bosch GSM 120 with MD120. The Proportions are exemplary!

The Chinese tried to copy the design of a successful device. It is Unclear why they closed the screwdriver for a pencil rubber cap. She Sits in the MD120 so tightly that I could not extract it. It is Necessary to use force, at risk to spoil a break of a rubber stopper or a case of device. This hole on Bosch is invented to mark the center of measurements with a pencil. This is where the sensor and measurements at this point are most accurate.

Comparison of Bosch GSM 100 dimensions with MD120.

Build Quality

The Size of MD120 is larger than that of Bosch GMS 100. It is longer about 2 cm and wider by 1 cm. Overall, the size of The device is quite convenient. He's a grasp.

There is a strap to keep out of your hands. The Manufacturer shifted the strap attachment to the left, as was the case with Bosch, on the right side of the chassis.

Plastic is good quality, odorless, visually durable. Joints are well adjusted, no backlash, squeak. The Sidewall is rubberized, but it is made only in the front of the body, where the hands are not particularly praised. From the bottom of the case the plastic is not rubberized, however, as with Bosch. So the rubberized-rather a marketing trick does not add some convenience to use.

In a battery compartment at Bosch under the closing cover on Perimetre there is a doolno soft rubber gasket. MD120 Has A rather rigid rubber insert, more reminiscent of plastic. If you hit the water, it can miss it. Bosch is really protected by IP54, about MD120 There are some doubts, though the device is collected soundly. Most Likely a spray or a wound in the rain will survive.

You can immediately note that the circuitry of devices is different. MD120 behaves differently than Bosch GMS 100.

One of the most noticeable differences-both Bosch devices have the possibility of calibration. This is useful for the case when the situation with the induced magnetic fields in the room is being used for normal. Perhaps the use of this option is a very rare case, but this possibility is exactly the same in MD120. At least the presence of such an option is not mentioned in the instructions and when you press the calibration keys, like the Bosch GMS 100, nothing in the behavior of the device does not change.


Before testing, briefly describe what information is displayed on the display MD120.

When working, pay attention to the Light ring. If the device detects the presence of an electromagnetic field in the mode of operation of the device "wire under alternating voltage" (AC live Wire), the "Light ring" is illuminated in red and does not blinking. If There is no electromagnetic radiation, the "light Ring" is green.

If the "light Ring" is illuminated red you should pay attention to two indicators: "Measuring indicator" and "Fine scale". In this case, the indicator should also show the icon "Charged wire", talking about the presence of a wire under the voltage.

Non-Magnetic metal of the electric cable device detects unreliable, so it is very useful to pay attention to the indicator "Non magnetic metal" No.

Testing will be carried out on three electrical wires:

  • The Wire from the light switch in the room. The Light is on, the wire is energized.
  • Socket loaded with low-power load in the form of a network router.
  • The Socket to which the consumers are not connected.

Electrical wires are deposited approximately at a depth of 2-3 cm in dry plaster.

Video comparison of professional hidden wiring detector Bosch GMS 100 M and expensive Chinese detector hidden wiring MD 120.

As a result of testing you can note the following:

  • Bosch GMS 100 M Professional its professionalism and price quite justifies. Driven by one button it stably detects the wire under voltage.
  • MD 120 Despite the fact that shows somewhat less stable results, still quite well copes with the detection of wires under voltage.
  • Since MD 120 is almost half the size of Bosch, it can be recommended for use at home and semi-professional use when the price of error is not so high.
  • The Results of work MD120 much better detectors hidden wiring sold on Aliexpress for a price of about 700 rub. I acquired this for testing-the accuracy of the definition is extremely low. The money Thrown out on the wind.
  • When using MD 120, before drilling the holes, it is necessary to check the presence of the wire in two modes: determination of metals and wires under tension (live wire/conductor).

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