Electrical
QA inspection checklist

Containment & First Fix

1. 1.

   Cable tray/trunking routes match design
   What to look forRoutes follow the M&E coordinated drawings. Tray loaded to no more than 60-70% of capacity. Bend radius respected — ≥ 8 × cable OD typically. Adequate space maintained between power and data (typical 200-300 mm parallel separation).
   Acceptable whenContainment per BS 8519 / BS 7671 cl.521. Cable separation: data/power minimum 50 mm in same trunking, 200 mm in parallel runs (BS EN 50174-2). Tray fill ≤ 60% by area for power, ≤ 40% for data. Routes per coordinated services drawings.
   StandardBS 7671:2018+A2:2022 — IET Wiring Regulations 18th Edition. BS 8519 — Selection and installation of fire-resistant cable systems. BS EN 50174-2 — Telecoms cabling installation.
   Common defectsCable tray overfilled — heat dissipation poor, derating not appliedData and power run together with no segregation — induced interferenceBend radius too tight at containment turns — insulation damageContainment routes clash with mechanical services (not coordinated)Tray fixings missed at junctions — visible sag
2. 2.

   Fixings and supports at correct centres
   What to look forFixing centres match manufacturer's loading table. Cable trays supported on two fixings minimum. Bracketry secure to substrate — toggles, anchors, or weld studs as appropriate. No long unsupported spans.
   Acceptable whenCable tray supports typically 1.5 m centres for medium duty, 1.0 m for heavy duty. Conduit supports per BS 7671: 0.75 m horizontal / 1.0 m vertical for 16-25 mm dia. Trunking 1.5 m horizontal / 1.75 m vertical.
   StandardBS 7671:2018 cl.522.8 — Mechanical support. BS EN 61537 — Cable tray and ladder systems. Manufacturer's loading data.
   Common defectsExcessive span between supports — visible sag, especially when cables addedPlasterboard plug fixings on heavy tray — pull out under loadLast support far from tray end — cantilever droopsSingle fixing on tray — rotation possibleFixings into wrong substrate — e.g. fire-rated plasterboard without resin anchors
3. 3.

   Fire stopping at all penetrations
   What to look forAll cable, conduit, and tray penetrations through fire-rated walls/floors sealed with appropriate fire-stop product (intumescent compound, mortar, batt, or pillow). Each penetration labelled with system, date, installer. Annular gap fully filled.
   Acceptable whenFire stopping rated to match the wall/floor — typically 60 or 120 minutes. System tested to BS EN 1366-3. Third-party certified (LPCB / IFCC / Warringtonfire). Labelling per BS 9999. Maintained on as-built fire stopping log.
   StandardBS EN 1366-3:2021 — Fire resistance tests for service installations. BS 9999:2017 — Fire safety in buildings. ASFP "Pink Book" — Fire stopping guidance.
   Common defectsFoam used as fire stop — generally not fire rated to required periodMineral wool stuffed in penetration without sealant — not a tested systemAnnular gap unfilled — typical at large bore conduitsNo labelling — installer/date/product not recordedWrong product for wall type — e.g. mortar in lightweight partition
4. 4.

   Back boxes level and at correct height
   What to look forBoxes at heights per Approved Document M / drawings — typically sockets 450 mm AFFL, switches 1200 mm. Level in both axes. Square — top edge horizontal. Box flush with finished surface — not proud or recessed.
   Acceptable whenHeights per Approved Document M: switches 900-1200 mm AFFL, sockets 450-1200 mm AFFL. Tolerance ±10 mm. Levels true ±2 mm in 200 mm. Box face flush with finish ±2 mm. Knockouts only where used; spares grommeted.
   StandardApproved Document M (Access to and use of buildings). BS 7671:2018 cl.526 — Electrical connections. BS 4662 — Boxes for the enclosure of electrical accessories.
   Common defectsSockets set below 450 mm AFFL — Part M non-compliantBoxes not level — visible to users, looks amateurBox recessed too deep — accessory will not screw flushMixed heights along same wall — boxes set off different datumsKnockouts not blanked — open to combustion gases / vermin
5. 5.

   Cable labelling in place
   What to look forCables labelled at both ends with circuit reference matching DB schedule. Permanent labels (engraved or printed, not handwritten on tape). Visible after install completion. CSA, length, and route also typically noted on data sheet.
   Acceptable whenLabelling per BS 7671 cl.514. Permanent legible identification at both ends and at intermediate accessible points. Engraved Traffolyte or printed sleeves. Cross-reference to as-installed schedule.
   StandardBS 7671:2018 cl.514 — Identification and notices. BS EN 60446 — Identification of conductors by colour or numerals.
   Common defectsHandwritten labels — fade and become illegibleLabels at one end only — circuit not traceable from far endLabels do not match DB schedule — circuit numbering changed but labels not updatedLabels removed during second fix — finishes contractor stripped themSleeves on multicore showing only colour, not circuit ref

Wiring & Connections

1. 6.

   Cable types match specification
   What to look forCable type printed on outer sheath — e.g. 6242Y T&E, 6491X singles, FP200 fire-rated, SY/CY screened. CSA correct for the design current after derating. Insulation rating matches voltage. LSF/LSZH for escape routes.
   Acceptable whenCables to BS 6004 (T&E), BS 6724 (LSZH), BS 7846 (fire), BS EN 50525 series. CSA per BS 7671 Appendix 4 design current and installation method. Fire performance per BS 8519 — Cat 1 (FP200/MICC) for life safety, Cat 2 for property protection.
   StandardBS 7671:2018 — Wiring Regulations. BS 6004:2012. BS 7846:2015 — Fire-resistant cables. BS 8519:2020.
   Common defectsPVC cable in escape route where LSZH specified — toxic smokeWrong CSA — 1.5 mm² used for 16 A circuit (should be 2.5 mm²)Cable derating not applied — bunched in conduitStandard cable used where fire-rated FP200 specified for emergency lightingCable crushed or damaged during pulling — sheath cuts
2. 7.

   Connections tight and terminated correctly
   What to look forConductors stripped to correct length — no insulation under terminal, no exposed copper outside. Screw terminals torqued to manufacturer's spec. No "fanning" of strands. Crimps fully cycled — colour-coded, ratchet not released until full close.
   Acceptable whenTermination per BS 7671 cl.526. Screw terminals torqued to accessory manufacturer's figure (typically 1.5-2 Nm for 6 A, 3-5 Nm for 32 A). Conductor fully captured, no strands escaping. Heat shrink on lugs where required.
   StandardBS 7671:2018 cl.526 — Electrical connections. BS EN 60998-2-1/2 — Connecting devices.
   Common defectsInsulation under screw — high resistance, overheatingStrands fanned out — short to live/earthLoose terminal — visible scorch marks at MCB after timeWrong crimp size — sleeve too big, bad mechanical holdNo torque applied — accessory connections "finger tight"Aluminium and copper joined without bimetallic connector
3. 8.

   Earth continuity verified
   What to look forCPC connected at every accessory and metalwork. Bonding of services (incoming gas, water, structural steel) at MET. Continuity tested with low-resistance ohmmeter. Equipotential bonding at bathrooms etc. per Section 701.
   Acceptable whenCPC continuity ≤ 0.05 Ω typical for short circuit. Main bonding to BS 7671 cl.411.3 — minimum 10 mm² to gas, water, oil, structural metalwork. Supplementary bonding in bathrooms, swimming pools per Section 701/702.
   StandardBS 7671:2018 cl.411 — Protection by automatic disconnection. BS 7671 Section 701 — Bathrooms.
   Common defectsMain bonding in 6 mm² where 10 mm² requiredGas bonding not within 600 mm of meter outlet — non-compliantCPC missing on metallic accessory (e.g. metal switch plate)Bonding clamp on a painted pipe — no electrical contactPlastic pipe replaced section without re-routing bonding
4. 9.

   Circuits correctly identified in DB
   What to look forDB schedule populated and inside DB door. Each circuit labelled at MCB with description (e.g. "Kitchen ring", "Bedroom 2 lights"). Circuit numbers match labels at accessories. Phase rotation correct on 3-phase.
   Acceptable whenDB labelling per BS 7671 cl.514. Schedule on hard-copy chart inside DB. Permanent label at each MCB. Phase identification by colour (brown/black/grey) and continuity from supply through to outlets.
   StandardBS 7671:2018 cl.514. BS EN 60439 (now BS EN 61439) — Low-voltage switchgear and controlgear assemblies.
   Common defectsHandwritten circuit chart on tatty paper inside DB — illegibleMCB labels do not match the circuit chartCrossed phase rotation on 3-phase outlet — motor runs backwardsSpare ways labelled "spare" but in fact connected (live, undocumented)No schedule at all

Testing & Commissioning

1. 10.

   Insulation resistance test passed

   Record: IR (MΩ)
   What to look forInsulation tester (megger) used at correct test voltage. All electronic equipment disconnected to avoid damage. Tested live-to-earth, neutral-to-earth, live-to-neutral. Results above minimum across every circuit.
   Acceptable whenPer BS 7671 Table 64 / cl.643.3: minimum 1.0 MΩ at 500 V DC for 230/400 V circuits (SELV/PELV 250 V test, ≥ 0.5 MΩ; FELV 500 V test, ≥ 1.0 MΩ). Below 200 MΩ on new install warrants investigation.
   StandardBS 7671:2018 cl.643.3 and Table 64 — Insulation resistance. IET Guidance Note 3 — Inspection & Testing.
   Common defectsReading just above 1 MΩ — moisture in conduit, deteriorating insulationReading low because electronics not disconnected (LED drivers, dimmers)Test voltage 250 V used on 230 V circuit (should be 500 V)Damaged cable in run — squashed or stapledEarth fault recorded but ignored
2. 11.

   Earth fault loop impedance within limits

   Record: Zs (Ω)
   What to look forZs measured at furthest point on each circuit. Reading ≤ 80% of maximum tabulated value (allows for cable temperature rise). High Zs investigated — usually long cable, undersized CPC, or poor connection.
   Acceptable whenPer BS 7671 Table 41.2 / 41.3: Zs depends on protective device. e.g. 32 A Type B MCB Zs ≤ 1.10 Ω at 80% (×0.95 for cold-test correction). 6 A Type B ≤ 7.28 Ω. RCD-protected circuits use lower 5 s disconnection time.
   StandardBS 7671:2018 cl.643.7 and Tables 41.2/41.3. IET Guidance Note 3.
   Common defectsZs above 80% of max — disconnection time may not be achieved at full loadLong radial circuit — Zs at end exceeds limitPoor MET connection — high Ze masks circuit Zs problemsWrong circuit type-tested — measuring at wrong endTest instrument battery low — readings drift
3. 12.

   RCD trip times within limits

   Record: Trip (ms)
   What to look forRCD/RCBO tested at ½ I∆n (must not trip), 1 × I∆n, and 5 × I∆n. Test on all four poles (0°/180°). Times recorded. Push-button test confirmed at handover. Type AC/A/B/F per load characteristics.
   Acceptable whenPer BS 7671 cl.643.8: at I∆n trips within 300 ms (general use), 200 ms (RCD-protected socket). At 5 × I∆n trips within 40 ms. Type AC for resistive, Type A for class 1 electronic, Type B for VSDs/PV.
   StandardBS 7671:2018 cl.643.8 — RCD testing. BS EN 61008/61009 — RCDs/RCBOs. BS 7671 cl.531.3.3 — RCD types.
   Common defectsType AC RCD on circuit with electronics — fails to trip on DC fault currentTrip time > 40 ms at 5 × I∆n — RCD aged or faultyTest only at I∆n (one quadrant) — not full BS 7671 testRCD nuisance tripping not investigated — likely upstream PE currentNo push-button test record
4. 13.

   EIC / EICR issued
   What to look forElectrical Installation Certificate (EIC) for new work, signed by the designer, constructor, and inspector/tester. Schedule of inspections and test results attached. Certificate references BS 7671 18th edition. NICEIC / NAPIT / ECA scheme number visible.
   Acceptable whenEIC per BS 7671 Appendix 6 — must include: design, construction, inspection & testing signatures; schedule of inspections; schedule of test results; particulars of installation. Issued within 28 days of work completion. Lodged with Building Control via competent person scheme.
   StandardBS 7671:2018 Appendix 6 — Model forms. Building Regulations Approved Document P (Electrical safety – dwellings).
   Common defectsEIC missing schedule of test results — not validSingle name signing all three roles (design/construct/inspect) without justificationOld form referencing 17th edition / withdrawn standardsBuilding Control notification not lodged for notifiable work in dwellings (Part P)Test results clearly fabricated — round numbers throughout

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