The slab is poured once. Every ceiling light, fan and switch-board route above it must be in place first, or the alternatives — chasing concrete or surface wiring — follow.
What Goes In Before the Pour
| Item | Practice |
|---|---|
| Conduits | 20 – 25 mm PVC, sized for the wires |
| Fan boxes | At fan positions, with hooks, taped |
| Light junction boxes | At each ceiling point |
| Draw wire | Left in long runs to pull cables later |
| Sleeves | Where services must cross beams, as allowed |
Routing Rules
- Avoid beam–column junctions, where steel is most congested and concrete must flow freely.
- Do not run conduits along beams; cross them only where the engineer permits, in sleeves.
- Keep conduits off the formwork so they do not reduce bottom cover.
- Avoid bunching many conduits together, which creates voids and weak spots.
- Use bends with gentle radius so cables can be pulled.
Pre-Pour Walkthrough
- Every ceiling point on the electrical drawing has a box
- Fan boxes at the centre of rooms as planned
- Conduits tied, not floating
- Box openings taped
- No conduit bunches at junctions
- Draw wires in long runs
The Short Version
Plan every ceiling point before the pour, tie conduits to the bottom steel, keep them away from beam junctions, tape every box, and walk the slab with the electrician before concrete arrives.
