Electrical: First Fix → Second Fix
Golden sequence (with builders & plumbers)
Demolition → Layout & mark-ups → Chasing/ceiling framing → Conduits & boxes (First Fix) → Cabling & tests → Close chases / board drywall → Plaster/skim → Paint 1st coat → Second Fix (devices & lights) → Commissioning → Final paint & clean.
Swapping steps causes rework, cracks, and hidden faults.
Step-by-step
1) Layout, load plan & safety
- Room-by-room points schedule (sockets, switches, data, TV, thermostat, appliances).
- Load calculation & circuit list (ring/radials, dedicated lines for oven, hob, AC, water heater, washer/dryer, etc.).
- Decide switching (1-way/2-way/dimmers/scenes), RCD/RCBO strategy, surge protection, and earthing.
- Mark routes on walls/floors/ceilings; agree heights & alignments with client.
2) Chasing & penetrations
- Cut vertical/horizontal chases only (no diagonals); respect depth limits for walls/floors.
- Core drill penetrations (hoods, outdoor lights, EV stub-outs) with sleeves.
- Protect structure: follow beam/column no-cut zones; confirm with GC/engineer when in doubt.
3) First Fix — conduits, boxes, supports
- Install conduits/trunking in chases and above drywall ceilings; include draw wires.
- Fix back boxes (flush/level) and junction boxes; align in rows.
- Provide nail/screw plates where studs are chased; sleeve through fire-rated walls/floors with intumescent seals.
- Coordinate with plumbing/HVAC to avoid clashes; keep clear of hot pipes.
4) Cabling & panel prep
- Pull cables by circuit; label both ends; leave slack in boxes.
- Terminate neutrals/earths in the main distribution board (MDB/DB) but do not energize yet.
- Provide separate circuits for high-load appliances and bathrooms (RCD/RCBO).
- Low-voltage/data: run in separate conduits; plan Wi-Fi AP locations.
5) Testing before close-up (hold point 1)
- Insulation resistance, continuity, ring (if applicable), and polarity tests.
- Megger results recorded; fix any faults now.
- Photograph routes, boxes, and labels for the handover pack.
6) Close chases & ceilings
- Builders: backfill chases, render/plaster; close drywall ceilings/walls after the pass at Step 5.
- Firestopping reinstated at penetrations; acoustic sealant at perimeters.
7) Skim & first paint
- Apply base/finish skim; sand; first coat of paint (reveals defects for patching).
- Protect boxes with covers to keep out plaster/paint.
8) Second Fix — devices & luminaires
- Fit sockets, switches, dimmers, thermostats, data plates; level & tighten.
- Mount light fixtures (recessed/pendants/LED profiles), drivers remote-mounted where planned.
- Connect appliances (isolation switches accessible).
- Label the distribution board (circuit schedule + breaker sizes).
9) Commissioning & certification (hold point 2)
- Functional test of every point; RCD/RCBO trip tests; earth loop impedance; voltage drop checks.
- Balance phases (if 3-phase supply).
- Record results; issue as-builts (PDF) and user guide.
10) Final paint, sealants & clean
- Builders: final coats; reinstall plates if removed for painting.
- Silicone/caulk around plates where specified; polish faceplates; site clean.
Coordination with other trades (what to lock early)
- Ceiling grids/bulkheads: give cut-out drawings for spots, linear LEDs, diffusers, access panels.
- Cabinetry & kitchen: exact positions for cooker switch, under-cabinet lights, appliance sockets.
- Bathrooms: mirror demist, shaver sockets, IP-rated lights, fan isolation, heated towel rail.
- HVAC: thermostat heights, condensate pump outlets, FCU isolators.
- Data/AV: conduit stubs for TV walls, projector points, rack/patch panel location.
Quality checkpoints (don’t skip)
- Before plasterboard: all cables tested & photographed.
- Before second fix: paint 1 done, walls flat; ceiling access panels fitted.
- At handover: labelled DB, spare breakers as specified, QR code/link to as-builts.
Safety essentials
- RCD/RCBO protection for sockets and wet areas; bonding of metallic services.
- Correct IP rating for bathroom zones; fire-rated fittings where ceilings are fire-separating.
- Isolation: local isolators for kitchen/heavy appliances and bathroom fans.
Common mistakes & fixes
- Boxes not level/depth wrong → use box extenders or re-set now (cheaper before paint).
- Overfilled conduits → respect fill ratios; add pull boxes.
- Shared routes with plumbing → overheating/condensation risk; reroute or sleeve/insulate.
- Unlabeled circuits → label at pull time; keep a live circuit schedule.
- Closing walls before testing → always test & photo first.
Cost & programme (percentages only; baseline = disciplined first-fix + second-fix rewire with standard fittings = 0%)
- Add smart dimming/scenes & drivers: +10–30%
- Premium faceplates/architectural lighting: +15–50%
- Extra data/AV infrastructure: +5–20%
- Fire-stopping & acoustic upgrades at penetrations: +5–15%
- Skipping hold-point tests (risked rework): downstream cost +20–40%
- Programme impact (doing tests & photos): +5–10% time now, rework/snag time −20–35% later
Deliverables for the client (value add)
- As-built drawings with point numbers and heights.
- Circuit schedule with breaker/RCD ratings and locations.
- Test certificates and warranty terms.
- User guide: how to reset trips, change dimming scenes, lamp specs, maintenance.
Quick checklist (print-ready)
- ☐ Points schedule approved (heights, types, finishes)
- ☐ Chases cut to code; sleeves at penetrations; no structural cuts
- ☐ Conduits/boxes fixed, aligned, labelled; low-volt separate
- ☐ Cables pulled & tested (IR/continuity/polarity); photos saved
- ☐ Chases closed; fire/acoustic seals reinstated
- ☐ Skim & first paint complete; boxes clean
- ☐ Second fix complete; all devices level; drivers accessible
- ☐ RCD/RCBO tests passed; DB labelled; as-builts & certificates delivered
