Spare switchboard capacity review
How to record spare switchboard capacity assumptions before using maximum-demand and phase-balancing results in Australian project planning.
Spare capacity is a labelled allowance
Spare capacity is useful only when the project can explain what it means. It may represent future load, contingency, a client allowance or a design target. It should not be hidden inside an existing load row.
The calculator can show how entered allowances affect worksheet totals, but it does not verify switchboard ratings, thermal limits, supply capacity or authority requirements by itself.
Review workflow
- Separate existing loads from future or spare allowances.
- Record the reason for each spare allowance.
- Keep units consistent with the load worksheet.
- Check whether the allowance affects one phase or all phases.
- Review maximum demand and phase balance before using the spare number in planning.
Spare capacity record
| Field | Record | Avoid |
|---|---|---|
| Allowance label | Future EV, tenancy spare, equipment spare or client allowance | Generic spare row |
| Basis | A, kW, kVA or percent with source | Number without unit |
| Phase effect | Single phase, three phase or grouped | Unallocated single-phase allowance |
| Review owner | Designer, estimator, facility manager or project note | No owner |
| Next check | Demand, phase balance, supply or cable review | Treating spare as approved capacity |
Boundaries
- Do not equate spare ways with spare electrical capacity.
- Do not hide future allowances inside present demand.
- Do not assume the supply, switchboard or protective device can accept the allowance.
- Do not describe the spare capacity output as approval.