When to run this checklist
A switchboard design is easy to get almost right. The single-line diagram looks complete, the circuits are drawn, yet small oversights in module count, group split or labeling only surface on site, when the enclosure is already ordered and the panel is being wired.
This checklist is for the last pass before you release a design. It does not explain how to design a board from scratch; it lists what to verify so the drawing you hand over matches the board that will actually be built.
Why common oversights reach the site
Most of the items here are not electrical faults. They are mismatches between the design and the board: a module counted wrong, a group split differently from the drawing, a label that no longer names the circuit it protects. Each is harmless on screen and costly once the enclosure is drilled and wired.
Such oversights survive a design review because reviews focus on the electrical logic, not on what the drawing asks the person building the board to do. The checks below cover the second kind of detail: the ones that only show up when the panel is assembled, wired and labelled.
1. Modules and enclosure
- Count modules from the real device widths: a 1-pole MCB is 1 module, a 3-pole device is 3, an RCD or RCBO takes 2 to 4.
- Keep 20 to 30% free modules so a future circuit does not force a new enclosure.
- Confirm the meter and the main incoming switch are included in the total; they are the items most often left out.
- Check the number of rows and the usable depth suit the devices and the wiring space they need.
2. Circuit groups and protective devices
- Every outgoing circuit sits in a named group with a protective device sized for its cable.
- Group by purpose, not by room position, so kitchen sockets and lighting are not mixed on one device.
- Verify residual-current coverage: not one device for the whole board, and each circuit that needs it is actually behind it.
- Check each device rating against the cable it protects, and that the incoming device covers the board total.
3. Phases and load balance
- On a three-phase board, spread single-phase groups evenly across L1, L2 and L3.
- Aim for a near-equal split; a large imbalance loads the neutral and skews the voltage.
- Count three-phase loads once, not once per phase, and recheck the split after any late change to a group.
Phase balance is the check most easily undone by a late edit. Moving a single socket circuit from one phase to another changes the totals, so if the split is not re-verified after a change, the drawing shows a balance the board will not have.
4. Labeling
- Every breaker carries a label naming its group, in plain words the person wiring the board will recognise.
- Cables and conductors are marked to match those labels, not left to position alone.
- Fix the naming scheme before anything is printed, so labels stay consistent across the set.
- Plan a copy of the diagram for inside the enclosure door.
Labeling is what turns the drawing into something usable on site. A board with correct devices but vague labels forces the next person to trace every circuit by hand, which is exactly the work a good schedule and a clear naming scheme are meant to save.
5. Documents and handover
- Release the design as a set: single-line diagram, panel layout, cable schedule and specification from one model.
- Generate the panel passport with the documentation so it travels with the board.
- Make sure the values on the drawing match the calculated results, with no stale figures left from earlier edits.
- Export in the format the client or contractor expects: PDF for reading, XLSX for the schedule.
When the diagram, the schedule and the specification come from one model, they agree with each other by design. Handing over a set produced from separate drawings is where mismatched figures usually creep in, so it is worth confirming the whole set was generated together rather than assembled by hand.
6. Final release check
| Item | Target | How to verify |
|---|---|---|
| Free modules | 20 to 30% reserve | Count devices, compare with the enclosure |
| Phase balance | Even split across L1 to L3 | Sum single-phase groups per phase |
| Group labeling | Every breaker named | Walk the board row by row |
| Document set | Diagram, schedule, passport | Check the export set is complete |
When every row passes, the design is ready to release. Run the same list after any significant edit, because a change to one group can move the module count and the phase balance at the same time.
The value of a checklist is that it is repeatable. The first pass teaches you where your own designs tend to slip; later passes get faster, and the number of surprises on site falls with each one.
FAQ
Is this checklist tied to one standard?
No. It covers practical items that apply whatever standard your region uses; the project standard controls the specific ratings it checks.
How often should I run it?
At the final pass before release, and again after any significant edit, since one change can move the module count or the phase balance.
Does it replace a full design review?
No. It is a release-readiness pass for common oversights; the detailed electrical design review still belongs with the engineer.