Often, when carrying out repair work or fixing any objects on the walls, it is required to determine the location of the hidden wiring. Without this, a drill or driven nails can fall on the phase wire and seriously injure the working person. Another nuisance is associated with the short circuit of the phase and zero buses, which are located close to one another in the wiring harness. All this forces you to somehow determine the route of laying the wires, without opening the finish and plaster of the walls.
For these purposes, there are special devices that respond to the electromagnetic field created by an electric current or determine the location of metal products. But what if such devices were not at hand? There are several known solutions to this issue.
Visual method
This approach, depending on the condition of the walls with hidden wiring, is used in the following 2 cases:
- during the renovation of the premises with a complete renovation of the plaster or finishing coating;
- the wiring is stretched in such a way that the initial sections of its laying are clearly visible.
The first case does not need explanation, since the necessary operations are carried out with a practically open wiring. In the second case, possible with the wallpaper removed, part of the wiring sometimes protrudes up to 20-40 cm on the surface of the walls in the form of a characteristic bulge or bump (as in the photo below).
Since according to PUE p.2.1.1-2.1.79 and GOST R 50571.15-97 it is allowed to lay it only along straight lines (horizontally and vertically) - it will not be difficult to extend them mentally and outline an approximate laying route.
Finding the location of the wires with a radio receiver or microphone
It is possible to determine the route of laying the power lines in the depths of the walls if you use ordinary radio receivers with AM range. To do this, you need to adjust it to a frequency of 100 kilohertz and press it tightly against the surface with the desired wire (as in the photo below in the text).
Important! The desired conductor must be energized, for which either a drill or a vacuum cleaner is plugged into the outlet in the tested branch (you can also use a razor or grinder).
Electrical equipment in operation will interfere with the supply line at 50 Hz.
The receiver at the second harmonic (100 Hz) will begin to respond to them, emitting a strong crackle. With distance from the hidden conductor, the intensity of the interference decreases. Instead of a radio device, it is allowed to use an e / m microphone with built-in coils. After connecting it to the jack of the "MKF" amplifier and when approaching the working area, you can hear the same interference in the speakers.
Extrapolation method
The last method is applicable in situations where there is complete confidence in the observance of the wiring rules. The fact is that according to existing regulations (see SP 76.13330.2016 year) it cannot be laid arbitrarily (diagonally, for example, or as shown in the photo below).
According to the rules, the wiring is laid in the grooves parallel to the joints of the walls with the ceiling and floor or perpendicular to them. By mentally marking the lines connecting two sockets horizontally or leading up to the junction box, you can very accurately find the points where you cannot drill and drive in nails.