drypy wrote: The gentlemen scared me a bit of all this, and I think I will do something to modernize the installation. I only have a question, if a specialist comes, what decisions can he make? I mean here especially whether it is necessary to forge the wall and tighten the cable to each socket and switch in the apartment, whether there is any option not to do it and have the electrics properly made, and what are the possible costs of such something, assuming that I do cables and forging alone.
Basic question:
Should it be correct or safe?
Correct, that is, in accordance with the law and standards. Since the law does not apply retroactively, installations that were made in accordance with the law and standards from 50 or 100 years ago are still properly made, because in accordance with the standards that were in force at that time. Therefore, in order for this installation to be valid, you do not need to do anything with it.
Contrary to appearances, zeroing, i.e. connecting the protective pins with the zero wire, is still correct, because it complies with the old law and standards. However, in the case of old installations, it can improve security, but also drastically worsen it. It all depends on the technical condition of this installation. In addition, it was not uncommon in old installations that a fuse was also installed on the neutral conductor, the blown of which causes the immediate appearance of 230V mains voltage on the protective pins.
For the installation to be correct and safe, it must be modernized and adapted to the current legal requirements and standards. Unfortunately, this requires a lot of protection measures, and so:
1. Dividing the PEN conductor into PE and N
2. Implementation of the equalizing bus with equalizing connections to all conductive installations (water, CO, gas, etc.)
3. Carrying out an earth electrode and connecting it to the equipotential bar.
4. Connection of the PE conductor with the equipotential bonding.
5. Installing anti-shock RCDs.
6. Bringing the lighting of a separate PE wire to each socket and point and connecting them with the protection pins and with the metal housings of lamps and chandeliers.
Either way, it requires forging furrows and replacing the wires with 3 wires or adding a separate protective conductor to these points.
Added after 7 [minutes]: lordpakernik wrote: If replacement is replacement, there is no need to add an additional cable. You replace the entire cable from the switchgear to the socket and lighting circuits. The TN network is also safe if someone has done it reliably, but with the development of the power industry at that time, it is better to replace the installation with one that complies with the standards.
Without exaggeration.
If the old wires are copper and in good condition, there is no need to replace them and do general demolition. You only need to run an additional protective conductor in the form of a single wire.
Of course, it is better to replace them completely. However, this is not always the case. Sometimes cables from 30 or 40 years ago are in better condition than new ones straight from the market, which often do not even have their nominal parameters.
Often, cables from supermarkets do not have cross-sections, which are given on labels or on the cable.
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If you do the electrical installation wrong, you can lead to someone's death. So think about where better to look for savings.
