BOSCH D-tect 120 Professional Wallscanner Detector Instructions

D-tect 120 Professional Wallscanner Detector

bosh test

Robert Bosch Power Tools GmbH
70538 Stuttgart
1 609 92A 4X7 (2021.02) T / 226

parts testing kit


inserting parts

inserting battery

side parts

bosh parts

Safety Instructions

All instructions must be read and observed.
The safeguards integrated into the measuring
tool may be compromised if the measuring
tool is not used in accordance with these

▶ Have the measuring tool serviced only by a qualified
specialist using only original replacement parts. This
will ensure that the safety of the measuring tool is maintained.

▶ Do not use the measuring tool in explosive atmospheres
which contain flammable liquids, gases or
dust. Sparks may be produced inside the measuring tool,
which can ignite dust or fumes.

▶ Do not open the battery. There is a risk of short-circuiting.

▶ In case of damage and improper use of the battery, vapours
may be emitted. The battery can set alight or explode.
Ensure the area is well ventilated and seek medical
attention should you experience any adverse effects. The
vapours may irritate the respiratory system.

▶ If used incorrectly or if the battery is damaged, flammable
liquid may be ejected from the battery. Contact
with this liquid should be avoided. If contact accidentally
occurs, rinse off with water. If the liquid comes
into contact with your eyes, seek additional medical
attention. Liquid ejected from the battery may cause irritation
or burns.
▶ The battery can be damaged by pointed objects such
as nails or screwdrivers or by force applied externally.
An internal short circuit may occur, causing the battery to
burn, smoke, explode or overheat.
▶ When the battery is not in use, keep it away from paper
clips, coins, keys, nails, screws or other small
metal objects that could make a connection from one
terminal to another. A short circuit between the battery
terminals may cause burns or a fire.
▶ Only use the battery with products from the manufacturer.
This is the only way in which you can protect the
battery against dangerous overload.
▶ Only charge the batteries using chargers recommended
by the manufacturer. A charger that is suitable for
one type of battery may pose a fire risk when used with a
different battery.
Protect the battery against heat, e.g. against
continuous intense sunlight, fire, dirt, water
and moisture. There is a risk of explosion and
▶ The measuring tool may not be 100 % accurate for
technological reasons. To eliminate hazards, familiarize
yourself with further sources of information, such
as building plans and photographs taken during construction,
etc. before carrying out any drilling, sawing
or routing work on walls, ceilings or floors. The accuracy
of the measuring tool may be affected by environmental
influences, such the level of humidity or there being
other electronic devices nearby. The structure and
condition of the walls (e.g. damp, building materials containing
metal, electrically conductive wallpaper, insulating
materials, tiles) and the number, type, size and position
of the objects may distort the measuring results.
▶ Make sure that you are properly earthed when taking
measurements. If you are not properly earthed (e.g. by
wearing insulating footwear or by standing on a ladder), it
will not be possible to locate live cables.
▶ If there are gas pipes in the building, check to ensure
that none of them have been damaged after completing
any work on walls, ceilings or floors.
▶ Live wires can be detected more easily when power consumers
(e.g. lamps, appliances) are connected to the
wire being sought and switched on. Switch off power
consumers and make sure that live cables are de-energised
before drilling, sawing or milling into walls, ceilings
or floors. After performing any kind of work,
check to ensure that objects placed on the base material
are not live.
▶ When attaching objects to dry walls, and in particular
when attaching them to the substructure, check to ensure
that both the wall and the fastening materials
have a sufficient load-bearing capacity.

Product Description and Specifications
Please observe the illustrations at the beginning of this operating

Intended Use
The measuring tool is intended for the detection of objects in
walls, ceilings and floors. Depending on the material and
condition of the base material, it is possible to detect metal
objects, timber joists, water-filled plastic pipes, conductors
and cables.
The measuring tool complies with the limits of the standards
specified in the declaration of conformity. The EU declaration
of conformity is available at
On this basis, clarification is required as to whether the
measuring tool can be used in places such as hospitals, nuclear
power plants and in the vicinity of airports and mobile
phone base stations.
The measuring tool is suitable for indoor use.

Product features

The numbering of the product features shown refers to the illustration
of the measuring tool on the graphic page.
(1) Top marking aid
(2) Left-hand and right-hand marking aids
(3) Concrete operating mode button
(4) Audio signal button
(5) Gripping surface
(6) Rechargeable battery/battery adapter release button
(7) Battery package
(8) On/off button
(9) Universal operating mode button
(10) Drywall operating mode button
(11) Display
(12) Indicator light
(13) Serial number
(14) Sensor area
(15) Battery adapter capacity
(16) Battery adapter receptacle
(17) Battery bay
(18) Non-rechargeable batteriesa)
a) Accessories shown or described are not included with the
product as standard. You can find the complete selection of
accessories in our accessories range.
Display elements
(a) Indicator for live wires
(b) Procedure indicator
(c) Object centre indicator (centre cross)
(d) Orientation arrows to determine the object’s centre
(e) Measuring indicator
(f) Service indicator
(g) Battery pack temperature monitoring indicator
(h) Interference from radio waves indicator
(i) Audio signal indicator
(j) State of charge of rechargeable batteries/non-rechargeable

Technical data

Universal detector D-tect 120
Article number 3 601 K81 3..
Max. detection depthA)
– Concrete operating mode 120 mm
– Concrete operating mode: Metal objects 120 mm
– Concrete operating mode: Cables and water-filled plastic pipes 60 mm
– Universal operating mode 60 mm
– Drywall operating mode 60 mm
Accuracy of object center measurement A) ±10 mm
Minimum distance between two neigh bouring objects A) 50 mm
Operating frequency range 2400–2483.5 MHz
Max. transmission power 0.1 mW
Max. altitude 2000 m
Relative air humidity max.
– For detecting objects 90 % (non-condensing)
– For classifying power cables 50 %
Pollution degree according to IEC 61010-1 2B)
Measuring tool power supply
– Rechargeable battery (Li-ion) 10.8 V, 12 V
– Non-rechargeable batteries (alkaline manganese) 4 × 1.5 V LR6 (AA) (with battery adapter)
Approx. operating time
– Rechargeable battery (Li-ion) 5 h
– Non-rechargeable batteries (alkaline manganese) 5 h
Weight according to EPTA-Procedure 01:2014
– With rechargeable battery 0.50−0.61 kgC)
– With non-rechargeable batteries 0.46 kg
Recommended ambient temperature during charging 0 °C to +35 °C
Permitted ambient temperature during operation –10 °C to +40 °C

Universal detector D-tect 120
Permitted ambient temperature during storage –20 °C to +70 °C
Recommended rechargeable batteries GBA 10,8V…
GBA 12V…
Recommended chargers GAL 12…
GAX 18…

A) Depends on operating mode, material and size of the objects, as well as material and condition of the base material
B) Only non-conductive deposits occur, whereby occasional temporary conductivity caused by condensation is expected.
C) Depends on battery in use
The serial number (13) on the type plate is used to clearly identify your measuring tool.
u The accuracy and detection depth of the measuring
result may be negatively affected if the condition of
the substrate is unfavorable.
▶ Protect the measuring tool from moisture and direct
▶ Do not expose the measuring tool to any extreme temperatures
or variations in temperature. In case of
large variations in temperature, leave the measuring
tool to adjust to the ambient temperature before
switching it on. The accuracy of the measuring tool and
the functionality of the display may be compromised if exposed
to extreme temperatures or variations in temperature.
▶ Avoid hard knocks to the measuring tool or dropping
it. After severe external influences and in the event of abnormalities
in the functionality, you should have the
measuring tool checked by an authorized Bosch aftersales
service agent.
▶ Certain ambient conditions fundamentally impair the
measuring results. These include, e.g. the proximity of
devices that generate strong electric, magnetic or
electromagnetic fields, moisture, metal building materials,
foil-laminated insulation materials or conductive
wallpaper or tiles. Therefore, also refer to other information
sources (e.g. construction plans) before
drilling, sawing or routing into walls, ceilings or floors.
▶ Hold the measuring tool by the intended gripping surface
(5) only, so as not to influence the measurement.
▶ Do not attach any stickers or labels to the sensor
area (14) on the rear of the measuring tool. Metal labels
in particular will affect measuring results.
Do not wear gloves when taking measurements
and make sure that you are properly
earthed. If you are not properly earthed, the
material identification of “live” wires may be impaired.
When taking measurements, avoid devices
that emit strong electric, magnetic or electromagnetic
fields. If possible, deactivate all
tools whose radiation could interfere with the
measurement and switch off the corresponding
functions or tools.

Measuring Tool Power Supply
The measuring tool can be operated either with conventional
non-rechargeable batteries or with a Bosch lithium-ion battery.
Operation with rechargeable battery pack (see figure B)
▶ Use only the chargers listed in the technical data. Only
these chargers are matched to the lithium-ion battery of
your measuring tool.
Note: The use of batteries unsuitable for your measuring tool
can lead to malfunctions or damage to the measuring tool.
Note: The battery is supplied partially charged. To ensure
full battery capacity, fully charge the battery in the charger
before using your tool for the first time.
The lithium-ion battery can be charged at any time without
reducing its service life. Interrupting the charging process
does not damage the battery.
The lithium-ion battery is protected against deep discharge
by the “Electronic Cell Protection (ECP)”. A protective circuit
switches the measuring tool off when the battery is drained.
To insert the charged battery pack (7), slide it into the battery
bay (17) until you feel it engage.
To remove the battery pack (7), press the release buttons
(6) and pull the battery pack out of the battery bay (17). Do
not use force to do this.
Operation with non-rechargeable batteries (see figure C)
It is recommended that you use alkaline manganese batteries
to operate the measuring tool.
The batteries are inserted into the battery adapter.
▶ The battery adapter is intended only for use in designated
Bosch measuring tools and must not be used with power tools.
To insert the batteries, slide the receptacle (16) of the battery
adapter into the battery bay (17). Place the batteries in
the receptacle as shown in the picture on the cap (15). Slide
the cap over the receptacle until you feel it click into place.
To remove the batteries (18), press the release
buttons (6) of the cap (15) and pull off
the cap. Make sure that the batteries do not fall
out by holding the measuring tool with the battery
bay (17) facing upwards. Remove the batteries. To remove
the receptacle (16) from inside the battery bay, reach
into the receptacle and pull it out of the measuring tool, applying
light pressure to the side wall as you do so.

Always replace all the batteries at the same time. Only use
batteries from the same manufacturer and which have the
same capacity.
▶ Take the batteries out of the measuring tool when you
are not using it for a prolonged period of time. The batteries
can corrode and self-discharge during prolonged
storage in the measuring tool.
Starting Operation
Switching on/off
▶ Before switching on the measuring tool, ensure that
the sensor area (14) is dry. If necessary, use a cloth to
dry the measuring tool.
▶ If the measuring tool has been exposed to a significant
change in temperature, leave it to adjust to the ambient
temperature before switching it on.
To switch on the measuring tool, press the on/off
button (8).
To switch off the measuring tool, press the on/off
button (8) again.
If no button on the measuring tool is pressed for approx.
5 minutes, the measuring tool will automatically switch itself
off to preserve battery life.
Check the measuring tool before each use. Safe operation
cannot be guaranteed in the following circumstances:
– The measuring tool has visible damage or there are loose
components inside the measuring tool.
– The measuring indicator (e) constantly deflects, even
when holding the measuring tool in the air.
– The measuring indicator (e) does not deflect at all, even
when holding a finger in the sensor area.
– None of the operating mode buttons light up.
Switching audio signal on/off
The audio signal can be switched on/off with the audio signal
button (4). When the audio signal is switched off, the audio
signal indicator (i) appears on the display.

Operating Modes

Once it has been switched on, the measuring tool defaults to
the universal operating mode.
To change the operating mode, press the button for the required
operating mode (button for universal operating
mode (9), button for concrete operating mode (3) or button
for drywall operating mode (10)). The selected operating
mode is indicated by the illuminated button.
By selecting the operating mode, you can adjust the measuring
tool to different wall materials and, if required, prevent
the detection of unwanted objects.
If the wall material is not known, you should begin with the
universal operating mode.

Universal operating mode

The universal operating mode is suitable for
most applications in masonry. Metal objects,
water-filled plastic pipes, electrical lines and

cables can be detected. Hollow spaces in brickwork
or empty plastic pipes with a diameter of
less than 2 cm remain potentially undetectable.
The maximum measuring depth is 6 cm.
Concrete operating mode
The concrete operating mode is particularly
suitable for applications in reinforced concrete.
Rebar, metal pipes, water-filled plastic pipes,
electrical lines and cables can be detected. The
maximum measuring depth is 12 cm.
Drywall operating mode
The drywall operating mode is suitable for detecting
timber joists, metal supports, electrical
lines and cables in drywalls (wood, plasterboard,
etc.). Water-filled plastic pipes can also
be detected. Empty plastic pipes normally cannot
be detected. The maximum measuring
depth is 6 cm.
How it works (see figure D)
The measuring tool checks the base material of the sensor
area (14) in the measurement direction A up to the maximum
detection depth. Objects that are different from the
material of the wall are detected.
Always move the measuring tool over the base material applying
light pressure, without lifting it off or changing the
The measuring tool can be moved in any direction B.
Measuring process
Position the measuring tool on/against the surface being inspected.
If there is an object below the measuring tool when it is set
down, the indicator light (12) lights up red if there is sufficient
signal strength, the measuring indicator (e) deflects
and an audio signal sounds.
If no object is detected when the measuring tool is set down,
the proceed indicator (b) is displayed and the indicator
light (12) lights up yellow. Move the measuring tool over the
surface without lifting it off, until the proceed indicator disappears.
If no object is detected below the measuring tool, the indicator
light (12) lights up green.
When the measuring tool approaches an object, the deflection
in the measuring indicator (e) increases, the indicator
light (12) lights up red and an audio signal sounds. When it
moves away from the object, the deflection in the measuring
indicator decreases.
For small or deep-lying objects, the indicator light (12) can
light up yellow without the audio signal sounding.
Wider objects in the base material can be identified by a continuous
high deflection of the measuring indicator (e). The
indicator light (12) lights up red.
▶ Before drilling, sawing or routing into walls, refer to
other sources of information to ensure that you eliminate
hazards. As the measuring results can be influenced
through ambient conditions or the condition of the
wall, there may be a hazard even though the measuring
indicator (e) does not indicate an object in the sensor
range and the indicator light (12) lights up green.
Determining an object’s centre
If an object is detected, the signal light (12) will light up red.
With sufficient signal strength, the orientation arrows (d) are
displayed to determine the object’s centre.
To locate the object’s centre, move the measuring tool in the
direction of the orientation arrow (d) displayed.
Over the centre of an object, the measuring indicator (e) will
exhibit maximum deflection, and with sufficient signal
strength, the centre cross (c) will appear. The orientation
arrow (d) will also disappear.
For a more accurate location of the object’s centre, pay attention
to the square; if there is sufficient signal strength,
this will be shown in the immediate vicinity of the object’s
centre in addition to the centre cross (c).
If the orientation arrows (d) are not displayed, an object may
nevertheless be located in the immediate vicinity.
u Always check all the signals of the measuring tool (indicator
light, measuring indicator and orientation arrows
for locating the object’s centre).
Indicator for live wires
The scan for live wires takes place automatically for each
measurement (regardless of the operating mode).

When a live wire is detected, the indicator for live wires (a)
appears in the display, the indicator light (12) flashes red
and the audio signal sounds at a faster rate.
– In certain conditions (such as behind metal surfaces
or behind surfaces with high water content), live
wires cannot always be detected. The signal strength of
a live wire depends on the position of the cable. Therefore,
take further measurements in close proximity or use
other information sources to check if a live wire is
– Static electricity can cause wires to be detected inaccurately
(e.g. over a large area) or prevent them from being
detected at all. To improve the detection, place your free
hand flat on the wall next to the measuring tool, in order
to remove the static electricity.
– Live wires can be detected more easily when power consumers
(e.g. lamps, appliances) are connected to the
wire being sought and switched on. Switch off electricity
consumers before drilling, sawing or milling into the wall.
Marking objects
If required, detected objects can be marked. Perform a
measurement as usual.
Once you have found the boundaries or the centre of an object,
mark the sought location at the top marking aid (1) and
the side marking aid (2). Connect the points with a vertical
and horizontal line. The boundary or the centre of the object
is located where the lines intersect.

Errors – causes and corrective measures
Error Cause Corrective measures
Measuring tool cannot be switched on. Battery pack or batteries empty Charge the battery pack or change the
Measuring tool is switched on but not responding.
Remove the battery pack or batteries
and put them back in again.
Battery pack temperature monitoring
indicator (g) is shown on
the display
Battery pack is outside the operating
temperature range or has
been subjected to large fluctuations
in temperature
Wait until the battery pack is within the
permitted temperature range again or
change the battery pack.
Note: When lifting the measuring tool off the
wall, the (g) indicator may appear briefly, even
when the temperature is normal.
Interference from radio waves
indicator (h) shown in display
Interference from radio waves
(e.g. from Wi-Fi, UMTS, radar,
transmitter masts or microwaves)
If possible, deactivate all tools whose radiation
could interfere with the measurement
and switch off the corresponding
functions or tools.
Service indicator (f) shown on
The measuring tool has developed
a fault and is no longer functional.
Send the measuring tool to an authorised
Bosch after-sales service centre.
Maintenance and Service
Maintenance and Cleaning
u Check the measuring tool before each use. If the measuring
tool is visibly damaged or parts have become loose
inside the measuring tool, safe function can no longer be
Always keep the measuring tool clean and dry to ensure optimum,
safe operation.
Never immerse the measuring tool in water or other liquids.

Wipe off any dirt using a dry, soft cloth. Do not use any detergents
or solvents.
After-Sales Service and Application Service
Our after-sales service responds to your questions concerning
maintenance and repair of your product as well as spare
parts. You can find explosion drawings and information on
spare parts at:
The Bosch product use advice team will be happy to help you
with any questions about our products and their accessories.
In all correspondence and spare parts orders, please always
include the 10‑digit article number given on the nameplate
of the product.
Robert Bosch Sdn. Bhd.(220975-V) PT/SMY
No. 8A, Jalan 13/6
46200 Petaling Jaya
Tel.: (03) 79663194
Toll-Free: 1800 880188
Fax: (03) 79583838
E-Mail: [email protected]
Great Britain
Robert Bosch Ltd. (B.S.C.)
P.O. Box 98
Broadwater Park
North Orbital Road
Denham Uxbridge
UB 9 5HJ
At you can order spare parts or arrange
the collection of a product in need of servicing or repair.
Tel. Service: (0344) 7360109
E-Mail: [email protected]
You can find further service addresses at:
The contained lithium-ion batteries are subject to the Dangerous
Goods Legislation requirements. The batteries are
suitable for road-transport by the user without further restrictions.
When shipping by third parties (e.g.: by air transport or forwarding
agency), special requirements on packaging and labelling
must be observed. For preparation of the item being
shipped, consulting an expert for hazardous material is required.
Dispatch battery packs only when the housing is undamaged.
Tape or mask off open contacts and pack up the battery
in such a manner that it cannot move around in the
packaging. Please also observe the possibility of more detailed
national regulations.

Measuring tools, rechargeable/non-rechargeable
batteries, accessories and packaging should be
sorted for environmental-friendly recycling.
Do not dispose of the measuring tools or rechargeable/
non-rechargeable batteries with
household waste.
Only for EU countries:
According to the Directive 2012/19/EU, measuring tools
that are no longer usable, and according to the Directive
2006/66/EC, defective or used battery packs/batteries,
must be collected separately and disposed of in an environmentally
correct manner.
Battery packs/batteries:
Please observe the notes in the section on transport (see
“Transport”, page 17).

Documents / Resources

BOSCH D-tect 120 Professional Wallscanner Detector [pdf] Instructions
D-tect 120, Professional Wallscanner Detector, D-tect 120 Professional, Wallscanner Detector, D-tect 120 Professional Wallscanner Detector, Detector