What is the main grounding bus for?

The main grounding bus is an element of distribution boards, which serves to connect PE conductors, working zero N and an external grounding circuit. The main purpose of GZSH is a component of the grounding system, which in turn is intended to protect a person from electric shock as a result of leakage current. In this article we will consider the device, purpose and installation rules of the main grounding bus in the shield.

Device requirements

All requirements for GZSh are given in paragraph 1.7.119- 1.7 120 PUE, Chapter 1.7. GZSh (in the photo below) can be made of copper or steel strip. The use of aluminum is not allowed.

Ground Conductor Connection

GZSh is located inside switchboards and has electrical contact with the housing, and also, maybe, as an independent device installed separately near the switchgear. Be sure to celebrate it. electrical safety mark Grounding.

Sign is grounded

PEN conductors are connected to the main grounding bus, as well as a wire with re-grounding. The number of places for fastening should correspond to the number of connected wires, that is, to provide the possibility of individual shutdown on the mains The wires are connected in such a way that removal from it was possible only with the help of a tool, as a rule, this is a bolted connection under the washer.

According to the rules of the PUE 1.7.119, as the GZSH inside the input device up to 1 kV, you can use the PE bus.

Product labeling is as follows:


Installation Nuances

The main ground bus is installed in an easily accessible place for maintenance. If unauthorized persons can access the installation site (entrances, basements), then it is installed in a box under the lock, and a ground sign is put on the door.


In the event that the building has several inputs, the GZS needs to be installed for each device and connected with potential equalizers, the cross section of which should not be less than half the PE (PEN) section of the one that has a larger section.

Main bus photo

It is also possible to connect them with third-party conductive parts, if they comply with the requirements of the rules and ensure integrity and continuity.

Important! What is the PEN bus and how to split a pen conductor in the shield we talked about in the corresponding article.

That’s all we wanted to tell you about the purpose and requirements of the main ground bus device. We hope the information provided was useful and interesting for you!

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