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How to upgrade a LV switchboard in a crowded electrical substation?

Published on 30 October 2020

As part of an installation upgrade (addition of new equipment, application improvements, process optimisation or expansion) the energy distribution requirements evolve. What are the possibilities of the low-voltage switchgear evolution when the space available in the electrical substation is crowded?

Extend the General Low Voltage Switchboard to preserve the existing system and adapt to space constraints

If the spare parts for the existing switchboard are still available from the manufacturer or in stock, it is still maintainable. It is not obsolete, so it is still operational for many years to come.  Before confirming with the original manufacturer the possibility of extending it, it is necessary to ensure that it can continue to be operated safely.

If all these elements are present, then the extension of the electrical switchboard is a good and cost-effective way to meet the new needs of the installation while adapting to the configuration of the room. To do this, several configurations are possible depending on the constraints of the electrical room.

Simple extension of the existing low-voltage switchboard

The following configurations solve the space problem when there is sufficient space in the vicinity of the existing switchboard.

Deported extension of the existing low-voltage switchboard with a bar duct

This solution is adapted in case of insufficient space in the close vicinity of the existing low-voltage switchboard. Indeed, this extension must be in the same room, close to the main one (about 2-3m) or in a different room with a sectioning device to isolate the two parts.

Change the General Low Voltage Switchboard to meet new needs and adapt to space constraints

This solution is recommended if the existing low-voltage switchboard is obsolete, dangerous or outdated. It is also suitable if you wish to keep the drawers interchangeable when the existing low-voltage switchboard is obsolete. However, this option involves more extensive work. Especially at floor level, where a study must be carried out to confirm that the load capacity per square meter is compatible with the weight of the new switchboard. If this is not the case, civil engineering works will have to be planned, but also a study of the cable connections (lengths and locations).

In some cases, it is possible to create a new electrical room with a shelter-type prefabricated substation solution. Different solutions are available, ranging from the traditional concrete substation to lighter solutions such as a shelter. This set is pre-equipped in the factory and is delivered ready to be connected.

In short: extension VS changing the low-voltage switchboard

Extension solutions save time compared to the complete replacement of a switchboard. They avoid the steps of removing the old switchboard and locating the existing cables, which saves considerable time and money. The complete replacement of a switchboard takes an average of 5 days, whereas an extension requires only one day's downtime for installation. The downtime is greatly reduced.

The stages of implementation to change a low-voltage switchboard VS to install an extension:

  New switchboard Existing switchboard extension
Locate all cables X  
Isolate the installation (switch off the power supply to the switchboard) X X
Disconnect cables X  
Remove the old switchboard X  
Civil engineering works if required (weight and dimensions) X X
Installing the new equipment X X
Re-wire all removed cables X  
Checking and testing X X
Restart the system X X


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