Avenler

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7. Distribution boards, single-line diagram and sizing

Distribution boards

The Distribution boards list, opened from the project page, contains the distribution board enclosures (at most 20 per project). For a new distribution board you give its name, its type (single-phase consumer unit, three-phase consumer unit, meter / service connection enclosure, sub-distribution board), for a sub-distribution board its parent, the enclosure (price list item) and its size (1–6 rows, 6–36 modules per row).

The phase count (1 or 3) can also be set independently of the type; left blank, the type decides (for a consumer unit the type itself is single- or three-phase, for a sub-distribution board / meter enclosure it is inferred from the circuits assigned to it). An explicit phase count takes priority: it decides whether the phase selector appears for single-phase devices, and both the sizing and the rule check use it.

The distribution board designer

The designer shows the enclosure as module slots arranged in rows, with fill bars.

  • On the right, the Add device palette: search by code or text; it only contains price list items that have module data (Module data). If a device has no price list item, the Suggestion button narrows the modules by kind, pole count, width and the circuit's protection; a single match is shown as a preview, with several candidates (or an unknown rated current) you must pick from the list, and nothing is written before you confirm.
  • Devices can be moved by dragging or with the arrow keys; Del deletes.
  • Device properties: label, circuits, “Downstream of” (RCD or main switch), phase.
  • New circuit button; Suggest from circuits: the program offers an arrangement with a preview, which you can accept or discard. If the arrangement does not fit in the enclosure, the program suggests a larger enclosure size that you can set right there. For a board tied to the drawing, the floor's circuits that are not yet tied to a board are included automatically; if the floor has several boards you can choose: only the circuits assigned to this board, all free circuits of the floor on this board, or the free circuits going to the nearest board.
  • The supply cable and its length can be given (needed for sizing).
  • Linking to the drawing: on the floor plan, in the properties of the distribution board device, it can be linked to the distribution board, and the list of Connected circuits can be given. The link is visible on both sides (“Linked to drawing” / “Not linked to drawing”).
  • In a meter enclosure, the meter and the main fuses must be added manually.

Checking the distribution board

The designer's Rule check panel runs rules: standard rules (e.g. missing RCD, missing or oversized protection, overloaded circuit), physical rules (does not fit in the enclosure, no module data, not placed), structural rules (difference from the drawing link) and practical rules (RCD loading, lighting behind one RCD, phase balance, spare ways, main switch). You can switch the practical rules on/off on the Distribution board rules page, and you can also set their severity and threshold; the standard and physical rules are fixed. Info findings can be hidden. Next to a "no module data" error there is a Pick from catalog button (also in the suggestion preview): the program reads the catalog item texts (type, poles, trip curve, current, mA), records the missing module data, and sets the matching item on devices that have none yet. It writes to your own settings, never overwrites existing module data, and tells you if no suitable item is found. If several catalog items fit, the program asks which one to use and remembers your choice.

Single-line diagram

An overview of the distribution board designer is given on the Distribution board designer page. For single-line diagrams in general, with an example figure: Single-line diagram. The Single-line diagram button opens the single-line diagram calculated from the distribution board and the circuit list (it is not a stored drawing; it always shows the current data). The paper size (A4/A3) and the orientation can be chosen; with many outgoing circuits it breaks onto several sheets, with a standard title block; Print / Save as PDF. The sizing columns (Ib, ΔU) also appear on it. If there is an error in the distribution board data, or a circuit does not get onto the diagram, a warning tells you.

Sizing (informative calculation)

In the designer's Sizing panel you see, for each circuit: the power (given, or suggested from the devices), the design current (Ib), the rated current of the protection (In), the current-carrying capacity of the cable (Iz), the length and the voltage drop including the drop of the supply; a value over the limit is red. For each distribution board it totals the phase loads and the size of the main switch. You can take the suggested power over into the circuit with one click (as an editor).

  • Grouping and temperature: if several power circuits run together along a cable route (e.g. in one conduit), the current-carrying capacity is reduced by the grouping factor (×0.70 for 3 circuits); you can set the ambient temperature on the Distribution board rules page (default 30 °C). The correction is shown as a small number below Iz.
  • Disconnection (Zs): the program calculates the fault loop impedance (supply Ze + supply cable + the circuit's line and protective conductors), and checks that the circuit-breaker reliably trips (B: 5×, C: 10×, D: 20× In). If not, Zs is red, and the largest permitted length is shown. Set the value of Ze (default 0.35 Ω) according to an on-site measurement or the supplier's data.
  • Length: if a distribution board belongs to the circuit on the drawing, the length is the longest path from the distribution board to the farthest device (for a branching circuit, not the sum of the branches). Without a distribution board, or with a disconnected drawing, it is the sum of the cable routes; a note indicates this.

Inputs: for the circuit, the power, cos φ, the diversity factor and the length; for the distribution board, the supply cable and its length.

Informative calculation. The current-carrying capacity tables, the voltage drop formula and the limit values are awaiting approval by an electrical designer. The calculation does not replace the designer's responsible sizing.

Module data from the catalogue

On the Module data page, the Add missing module data from the catalogue button lists in a preview the price-list items that can be interpreted and have no module data yet. After checking, Save records them; existing own or shared data is not overwritten. For an ambiguous item you choose from a list; in shared mode only an admin can do this.