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Equalization Systems

 


Equalization SystemsAbout the main and additional potential equalization systems and their functional purpose.

Residential building. Many floors and apartments. Entire kilometers of communications: wires, metal pipes, ventilation ducts, metal hoses and the like. Our apartments have various metal bathtubs, sinks, heated towel rails and you never know what else. In other words, the whole house is simply full of elements and structures capable of conducting electric current, but often not intended for this.

However, each conductor has electrical potential. This is just the law of physics. Potential is a relative value. This means that the electric potential of, for example, the metal surface of the refrigerator in itself does not matter at all. The only important thing is how much higher or lower the potential of the water pipe passes from it (the refrigerator) in relative proximity.

If there is a difference between the potential of the refrigerator and the potential of the pipe, then this difference can be considered voltage. Someone may suggest that such a voltage cannot be significant: after all, both the body of the appliance and the water pipe should not be “out of phase”. But you should not rush to conclusions. In fact, there are so many reasons why even a harmless metal ventilation duct can acquire a dangerously high relative electrical potential.

Among these reasons, for example, not only failure of the insulation of the phase conductors of the cables of the power supply system, but also atmospheric overvoltages, static electricity, stray and circulating currents of grounding systems and much more.

And what to do? How to protect yourself from all these misfortunes and live in peace without fear that one day we will be shocked by our own bathtub?

This issue is decided by the creation of potential equalization systems. Her idea is quite simple. If live parts have a direct electrical connection, then their potential is always the same, and voltage between them will not arise under any circumstances.

Therefore, the potential equalization system includes everything that can become dangerous: namely metal pipes, building metal structures, lightning protection devices, boxes, trays. It all connects to main grounding bus (GZSh) at the entrance of the building. Such a system is called potential equalization system.

But until the engineering communications reach a single apartment located on some high floor, the distance from the main building can become impressive. The laws of electrical engineering, characteristic of the so-called "long lines", will come into force.


In accordance with these laws, the resistance of long conductors cannot be neglected. That is, the electric potential of the same metal pipe at the entrance to the building and on the fifteenth floor can differ, and very much. Thus, the main potential equalization system becomes less and less effective as you move away from the GZS.

Therefore, each apartment has its own additional potential equalization system. Elements that are included in it are connected to the PE bus (or PEN) in the apartment or house panel. This is again water pipes, ventilation ducts, and besides this, bathtubs, sinks and other voluminous metal objects.

Additional potential equalization system in the bathroom

Additional potential equalization system in the bathroom

Not every electrician repairing or replacement of apartment wiringknows about potential equalization systems and attaches due importance to them.Therefore, it is better for each homeowner to monitor the condition and quality of the implementation of such a system in their apartment on their own, without hoping for anyone else. After all, this is a question, first of all, of personal security.

Alexander Molokov, https://env.electricianexp.com

See also at bgv.electricianexp.com:

  • Power supply and bathroom lighting
  • How to make the washing machine not shock
  • Diagnostics of the electrical wiring of the apartment before buying
  • Electrosafe private residential building and cottage. Part 1
  • Step voltage and potential equalization
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    Comments:

    # 1 wrote: Natasha | [quote]

     
     

    And to me the electrician from the house management, when I was making a socket in the bathroom for the washing machine, said that with the old type of wiring, which is simply with zero and phase, the potential equalization system can in no case be done, since it is very dangerous! A potential equalization system can be done only after replacing all the wiring in the apartment !!!

     
    Comments:

    # 2 wrote: | [quote]

     
     

    The meaning of the words of this electrician is that in old houses the wiring is 2-core i.e. phase and zero. Therefore, some unscrupulous specialists may suggest that you make grounding by connecting a grounding conductor to zero, such as "they connect to the shield anyway." This is the danger, because in the event that the neutral conductor is burned somewhere in the shield, everything that you grounded may be energized the current will flow not through the neutral conductor, but through pipes, bathtub housings, etc. Therefore, with a 2-wire system, the grounding conductor must be pulled separately from the shield, where it must be connected to the grounded shield body or, preferably, the grounding conductor (as they say the main grounding conductor (bus)). After that, in the apartment you must connect all the conductive, metal parts of pipes, bathtubs, sinks, etc. at one point connected to the grounding conductor, that is, to equalize the potential. The work is laborious, so he told you so.

     
    Comments:

    # 3 wrote: | [quote]

     
     

    Before you start installing the control system, you need to know one thing: if the TN-C grounding system is in the house, then you can not do the installation in any case! This is deadly for other residents of the house who did not do the SOUP. For the performance of such actions that entailed death or injury, the criminal liability in full.

     
    Comments:

    # 4 wrote: Alex gal | [quote]

     
     

    What nonsense!

    The potential equalization system and the primary and secondary are mandatory with any grounding system. We read PUE7:

    1.7.83. The system of additional equalization of potentials must interconnect all simultaneously accessible open conductive parts of stationary electrical equipment and third-party conductive parts, including accessible metal parts of building structures of the building, and zero protective conductors in the TN system and protective grounding conductors in IT and TT systems, including protective conductors of receptacles.
    To equalize the potentials, specially provided conductors or open and third-party conductive parts can be used if they satisfy the requirements of 1.7.122 for protective conductors with regard to conductivity and continuity of the electrical circuit.

    That is, there are no restrictions for the TN-C system. Anyway, you need to be afraid not of imaginary criminal liability, but of the fact that one day you will be killed by electric shock in the absence of an equalization system in the bathroom. Especially now, when residents are massively replacing steel pipes of risers with plastic ones on their own. In this case, the circuit of the main equalization system can be interrupted anywhere and dangerous voltage will appear on the pipe. Where it comes from is the tenth thing ... I read about the case when an electric shock killed a man who climbed out of the bathtub and took up a heated towel rail.It is not known where the voltage on the pipe came from, but if an equalization system with a good metal bond between all surfaces conducting an electric current had been made in the bathroom, nothing like this would have happened.

     
    Comments:

    # 5 wrote: Paul | [quote]

     
     

    A potential equalization system is a very important and necessary thing! The grounding system has resistance, although not much. Therefore, when an electric current flows through one part of it, for example, when a protective device trips or breaks, then the other part of the grounding conductor, through which the current did not even pass, is energized. This voltage can cause the appearance of circulating currents, the effect of which is almost unpredictable. To prevent this, connect all metal enclosures of the devices to be earthed and the building structures accessible for touch, as well as metal pipelines, bathtubs, etc. Now, if the grounding is energized, under it will be all the elements that are accessible for touch, which will automatically reduce the likelihood of electric shock. From all this we can conclude that the potential equalization system is a very important way of protection when indirectly touched and to ensure electrical safety it must be organized during the repair and modernization of apartment wiring.

     
    Comments:

    # 6 wrote: | [quote]

     
     

    I think with TN-c the equalization system of potentials in the bathroom should be done like this .... we connect the bathroom, heated towel rail, mixers (water pipes and sewers - we don’t touch plastic ones). It is better not to touch the washing machine (it is connected through the difavto without PE).

    What to do with a possible step voltage? This is when the “earth” of a neighbor sits on a heated towel rail, there is a breakdown of insulation in him, and when we climb out of the bathroom we put our feet on the floor and get hit by voltage?

     
    Comments:

    # 7 wrote: | [quote]

     
     

    Recently made repairs in the bathroom. We changed metal pipes to plastic ones and put a stainless steel heated towel rail. They connected the coil and metal pipes with wires. As I understand it, this is a potential equalization system. For several months, several coils were changed, because after a while, micro holes appear on the coil and water oozes. Plumbers attribute everything to stray currents, although when the old "Soviet" coil was standing there were no problems. Are there any ideas or tips? Thanks.

     
    Comments:

    # 8 wrote: | [quote]

     
     

    Paul, at my customers in Khrushchev’s, with a 2-wire system, the taps are shocking, is this the same case?

     
    Comments:

    # 9 wrote: | [quote]

     
     

    Yes, that is the case. It is necessary to pull the 3rd wire from the shield.

     
    Comments:

    # 10 wrote: | [quote]

     
     

    Alexander,
    The problem is that you have plastic pipes. You need to ground the coil on a metal riser and problems will leave you.

     
    Comments:

    # 11 wrote: | [quote]

     
     

    If the taps in the bathroom are shocking, then perhaps the neighbors from above or below steal electricity, using the zero point of the heating pipe.