Why do you need a zero bus in the shield and how to connect it

A zero bus is required in order to connect the grounding conductors (PE) and the working zeros (N). Requirements for installation and designation of zero tires are reflected in the PUE in paragraphs 1.1.29-1.1.31 (see Chapter 1.1) The scope of this design is a direct or alternating current network with a voltage reaching 400 Volts. To date, it is practically impossible to imagine the assembly of an electrical panel without using special tires, so in this article we decided to consider the design and purpose of the zero bus.

Design Features

Upon a detailed examination of the structure, it can be noted that it is a conductive core and a base made of plastic, which is intended for installation on a DIN rail.

In the photo, the appearance of the NS:

The conductive core contains holes and clamping bolts for fixing the conductors in it, as well as for accurate and safe wiring inside the N. conductor switchgear. They differ in NS both in the installation method (case) and in the number of mounting holes, respectively, in length.

To ensure a high-quality connection, as well as simplify further maintenance, the busbar is made of a single conductive element of a sufficient size of electrotechnical copper or brass. With a different number of bolt clamps to which the zero (N) conductors are connected.

Distinguish NS in the case and the ground bus without the case, externally conductive elements are identical. A zero bus is made in the housing or an insulator is installed. For the correct functioning of the differential protection devices, it is necessary to correctly connect them, and in the switchboard, separate the N conductors from PE. In the case of a metal shield, this can only be done by isolating the neutral conductor from the housing.


The use of a zero bus makes it possible to solve several very important problems:

  1. First of all, you can create several points at once for connecting loads from a common input to a zero-type conductor.
  2. Ground the visible type with a cover made of transparent material that covers the terminals.
  3. Significantly increase the effective use of protective automatic devices.
  4. Ensure continuity of the circuit from the ground to the specific load.
  5. To fulfill the important condition, which provides for the separation of wires of zero (protective) and working types. About, how to split a pen conductor, we told in a separate article.


Now there are very clear requirements for choosing zero tires. The most important rule is not to exceed the wire cross section of a similar indicator in the GZSH. To make you understand, there is the possibility of entering into the box from one to four dozen wires.For example, for option 3 to 40, a wire is provided, the cross section of which reaches 3 millimeters with a maximum allowable connection of four tens.

Regarding technical characteristics, we have provided some of the parameters in the table below. Each manufacturer has its own design features and characteristics of zero tires. For an example, we took IEK products:

IE from IEK

Installation Rules

NS mounting is possible both on a special rail and in an electric panel. Installation options are available both in a closed and an open way. The open method is perfect for a cabinet that will be closed to unauthorized persons. The closed version is used in situations where equipment connected to very important elements is used. As an example, we can give a power-type socket for a different electric tool.

Switchboard photo

The video below clearly shows how to install the NS onto a DIN rail and how to fix it more reliably:

So we examined the design and purpose of the zero bus. We hope the information was useful and interesting for you!

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(1 votes)


  • Vadim

    Hello! Are there any guidelines for installing zero bus on a din rail? In particular, he is interested in whether it is possible to install the bus close to the machine (photo 1), or is it necessary to put a separator (photo 2)?

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  • maxim electric master

    It is not advisable to put the zero bus in tight to the machine, as well as to the grounding bus. So it is better to put the tires horizontally to each other, under the guns, and between two at least two centimeters between them and other contacts, so that there would be no pickups and short circuits when moisture gets in.

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