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 (catalogue item) and its size (1–6 rows, 6–36 modules per row).

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 catalogue items that have module data (Module data).
  • 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.
  • 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.

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.