Control Cabinet Creates Equipotential Bonding Without An Earth Strap

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-11-26 11:39

For electrical switchgear, earthing metallic parts has a high priority for safety reasons. The reason is obvious: in the event of a fault - for example, if a housing part could be under voltage - this would endanger people. And a housing should protect against the unintentional contact of life-threatening voltage. In low-voltage switchgear, all metallic frame and housing parts for which there is a risk of potential spreading must be connected to an earth connection.

Attach earthing straps

As a rule, earthing straps made of copper wire create such a potential equalization. These are flexible and can therefore securely connect moving parts such as doors to the housing. In the case of a control cabinet, the frame, the side walls, the control cabinet roof or other flat parts usually have to be connected to the protective conductor via the grounding straps. However, there is also a source of error here, since the workshop employees have to manually attach the earthing straps during assembly. If an earthing strap is forgotten, the finished switchgear is functional, but in the event of a fault it can endanger people.

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Equipotential bonding even without an earthing strap

In order to facilitate the implementation of the electrical protective measures, Rittal GmbH und Co. KG has developed an effective solution for the TS 8 baying system. The manufacturer automatically connects the side parts, the control cabinet roof, the rear wall and floor panels to the frame during assembly. Here, special claws or washers press through the electrically non-conductive surface coating of the flat parts and thus establish reliable contact. This means that all flat parts are conductively connected to the frame, so that separate earthing straps can be dispensed with in many applications. An earthing strap is only required for the control cabinet door. The contact resistance between the flat parts and the control cabinet frame is less than 0.1 ohm and thus corresponds to the empty housing standard DIN EN 62208.

Simplified assembly and increased security

In the workshop, this automatic equipotential bonding is intended to reduce the amount of material used. In addition, the time-consuming installation of up to seven earthing straps per control cabinet can be omitted. Finally, according to the manufacturer, disassembly and reassembly of the flat parts is easier, since the grounding straps do not have to be removed and reattached every time. In the course of a risk assessment, users must clarify whether the constructive measures of an automatic equipotential bonding are sufficient or whether separate earthing straps are required to meet the safety requirements. (ce)

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