The cold shower from the drilled water pipe is a typical caricature of the clumsy do-it-yourselfer. So that this doesn't happen to you, you should explore the wall before drilling. We tell you, what you need to look out for when using cable locators.
With modern cable locators, the wall should be almost transparent, if you could believe the promises of some manufacturers. But unfortunately that is not the case, because the technology used is often much too simple, around the in walls, to precisely locate lines running on floors or ceilings. Cable locators are already available at prices from around 15 offered in euros. your principle, to detect metal, is simple.
METAL SEARCH
The line locators generate an electromagnetic field, affected by magnetic materials. If you drive the device over the wall, the sensor recognizes this from the change in this electromagnetic field, if there is metal in the wall. This method works relatively well with magnetically effective ferrous metals. The thicker the iron and the closer it is to the wall surface, the safer it can be located.
For non-ferrous metals such as aluminum, However, copper and other non-ferrous metals deflect the electromagnetic field much less. Water pipes made of copper or the thin copper wires of the power lines can therefore often only be recognized with this method, if you are close to the wall surface. Deshalb haben fast alle Leitungssuchgeräte zusätzlich einen Sensor, who checks, whether an alternating electric field with 50 hertz is present. Such an electric field is always present, when a power line is under AC voltage.
CALIBRATION
The cheap line finders must first be calibrated with a small setting wheel. For the highest sensitivity, this is turned up so far in the middle of the room, until the device shows metal. Then turn the adjusting wheel back just far enough, that the display goes out again. However, if the device sounds an alarm when it is placed on the entire wall, you have to at a wall point, where there is definitely no metal, recalibrate. Even if the area, in which the device indicates metal, is very big, sometimes reducing the sensitivity helps, to better locate the position of the line.
AEG is offering the Explorer for approx 32 Euro a line finder, which is housed in the additional handle of the impact drill. That's a great solution, because the line finder is always at hand with the drill. Too bad, that the location technology of this device is just as simple, as with the cheapest line finders.
POWER LINES
Are the fuses turned off or is the line to a ceiling light switched off and therefore generally free of voltage, no alternating field can be detected either. You should therefore definitely switch on the ceiling lights in the room when looking for electrical cables. But be careful: For lines with three-phase AC voltage (so-called three-phase lines), which are often also used for the cooker connection, the electric fields of the three phases cancel each other out. The measuring devices can therefore not detect any alternating electric field here. One can only hope, that the devices can at least locate the thicker copper wires.
The detection depth also depends on the building material. In the case of concrete, it often does not go further than 5 cm. In some bathrooms, the devices even fail completely and show metal on the entire tiled wall. The reason for this is the high proportion of iron oxides (Rost) in the tiles, mostly in those with slightly reddish shards, which have a ferromagnetic effect.
DEPTH MEASUREMENT
More expensive device from about 40 Euro are often equipped with several measuring sensors and more complex electronics. They make it possible with the same working principle, locate the position of the metal in the wall more precisely. With a bit of luck, the display on the more expensive devices for ferrous metals will match the actual position to about ±1 cm.
At the DMO 10 from Bosch, for example, the depth of the metal in the wall can also be determined with an additional measurement. In the case of low-lying rebars, a short dowel can be set. However, this depth measurement does not work when detecting the alternating field of power lines. Here should – for your own safety – not be drilled into the wall.
PLASTIC PIPES
A special feature is the new wall scanner D-tect 100 by Bosch. It also uses a capacitive measuring method, but with very high frequencies, which are almost in the radar wave range. With it you can practically change any change in the wall up 10 track cm depth, even plastic water pipes and sewage pipes. The operating instructions are practically built into the D-Tect. The device guides the user through the various work steps via a display.
Depending on the wall material, three modes can be selected, to adapt the sensitivity to the building material. Modus 1 (Solid building materials such as concrete or solid blocks) shows all voids in the wall. Modus 2 is suitable for lightweight walls and hollow blocks. He ignores cavities in the building material, but shows metal, electrical and water-filled lines.
A special feature of the D-Tect is the built-in chassis. It's not just for that, guide the device more easily on the wall. Sensors on the wheels transmit the movement of the device to the electronics and help locate lines. When driving over the wall, the display shows each object found as a moving bar. The possible drilling depth is also displayed. Meet the D-Tect 100 it is possible for the first time, to locate almost all changes in the wall, and it also indicates plastic water pipes and power lines. However, he does not recognize the difference between the two. Another disadvantage is the high price. The professional device is scarce 870 Euro much more expensive than most other line locators. However, anyone who has drilled into a line and knows the follow-up costs, White, that such a device can quickly pay for itself, at least for craftsmen.
WOOD SEARCH
Some locators, such as Laserliner's Zircon MultiScanner Pro, can also locate wooden substructures. To do this, they use a capacitive measurement with a low-frequency electrical field. Such devices are helpful, when heavy objects are to be attached to drywall. Because when the wooden substructure is tracked down, the screws can be screwed directly into the beams.