LV installation systems: internal organisation (2/2)

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As promised in our previous article, it is time now to make a focus on Wall-Mounted panels.

Wall-Mounted (WM) Panels

We have to take in consideration the following elements which are specific to Wall Mounted panels:

  1. As their type name suggests, they are always installed against a wall. Therefore, back access is impossible.
  2. Ratings, as well as physical dimensions are smaller, while the number of panels tend to be greater. Therefore, simplicity is paramount.

Taking into account these elements, the preferred internal architecture for WM panels would be would the following:

  • The Bus Bars.
    • The VBB will be preferably installed at the BACK and a centralised Distribution Terminal Bloc will be used.
  • The Power Cables or Busways.
    • Incoming can be both at the TOP AND at the BOTTOM.
    • Horizontal Incomings require SEPARATE CABLEWAYS.
  • The Access is FRONT ONLY.
  • Grounding should be easily modified, i.e. independent from the main Bus Bars location (HBB).
  • Control Power, Auxiliary Wiring, Communications Network, I/O, and the like: EMC constraints respected. Preferably, at a certain distance from power distribution, and in any case not parallel to it, unless there is a metallic barrier in between.
  • A particular local habit, in Northern Europe, consists of the installation of the incoming switchgear in the incoming duct. VBB may also be in the duct.
  • For the sake of simplicity the incoming and the outgoing functional units may be similar.
Examples of the internal organisation of Wall-Mounted LV panels with front access



There is one last aspect that we have not discussed yet: is there a specific set of physical dimensions (Height, Width, Depth) that should be preferred?

What could be the interest to prefer one set of dimensions to another?

Well, we can identify several advantages:

  • Easy values to remember.
  • Consistency with related products and devices.
  • Consistency with all major manufacturers. The 25mm and the 9mm pitches are a kind of de facto standard. The standard width for Mini Circuit Breakers (MCB) is a multiple of 9mm. A module is considered to be equal to 2x9mm width.
  • Easy upgrade and expansion.
  • Full capacity of the panel known at the beginning, which eases the civil work.
doc 5 image 5
Example of modularity of a Wall-Mounted LV panel

External dimensions of the panel and of each functional unit:

  • All the external dimensions are in 25mm pitch.
  • For each panel, whether FS or WM, its dimensions (H, W, D) are equal to the sum of the dimensions (H, W, D) of the individual frames which are associated in the panel.

Internal dimensions:

  • There are several different habits regarding the number of modules to be installed in one DIN raw. e.g., in Italy it is equal to 36, in most other countries it is equal to 24. For residential applications the most common worldwide is number is equal to 18 and 12 modules.

Writtent by Frederic Waterlot and Daniel Barstz



  • Youssef Adel

    8 years ago

    Thanks for your effort, I’m asking about more documents about how to design LV ED Panels and the standards considered through this procedure,thanks in advance.

  • Frederic Waterlot

    8 years ago

    Thanks for your comment Youssef, I join a link with Schneider web site.
    If you need more information don’t hesitate to contact your Schneider Electric local subsidiary

Comments are closed.