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Educational use: ElectraCore supports learning and preliminary checks. It does not replace a competent electrician or engineer. Verify results, equipment data, and current local regulations before installation or live work.
Courses/Cable Sizing & Installation/Full Cable Sizing Design

lesson · 8min · Lesson 26 of 28

Documenting the cable schedule

Course syllabusCourse overview
01Current-Carrying Capacity
  1. ReadHow CCC tables work: Appendix 4
  2. ReadReference method A: enclosed in conduit
  3. ReadReference method B: clipped direct
  4. ReadReference methods C, E, F, G
  5. exerciseCCC selection problems
02Derating & Correction Factors
  1. ReadAmbient temperature correction (Ca)
  2. ReadGrouping correction factor (Cg)
  3. ReadThermal insulation factor (Ci)
  4. ReadDepth of burial correction (Cs)
  5. exerciseApplying multiple correction factors
03Voltage Drop Calculations
  1. ReadWhy voltage drop matters: Reg 525
  2. ReadmV/A/m tables and how to use them
  3. ReadCalculating voltage drop for single-phase
  4. ReadThree-phase voltage drop
  5. exerciseVoltage drop problems set
04Armoured Cables
  1. ReadSWA construction: layers and materials
  2. ReadUnderground cable installation methods
  3. ReadSWA as protective conductor?
  4. ReadXLPE vs PVC insulation
  5. exerciseSWA sizing exercise
05Mineral Insulated (MICC) Cable
  1. ReadMICC construction and applications
  2. ReadFire performance cables: FP200, LSOH
  3. ReadCable selection for life safety systems
  4. quizFire cable quiz
06Full Cable Sizing Design
  1. ReadEnd-to-end cable sizing: worked design
  2. ReadDocumenting the cable schedule
  3. ReadCommon errors and how to avoid them
  4. quizFinal assessment
Lesson · 8min
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In this lesson

PurposeCore theoryWorked exampleKnowledge checkSources

In this lesson

PurposeCore theoryWorked exampleKnowledge checkSources
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ElectraCore lesson handout

Documenting the cable schedule

Cable Sizing · Lesson 26 · Advanced

AdvancedReview: professional review pending

Purpose

Produce a cable schedule that is a controlled, auditable design record rather than a list of sizes.

Before you beginCable sizing workflow · Fire strategy and safety-service basics

Learning objectives

  • Identify the governing function
  • Select evidence on the correct basis
  • Coordinate the complete installed system
  • Record limitations

A useful schedule lets another competent person reproduce the selection and reconcile it with the installed route, device, termination and test evidence.

END-TO-END CABLE DESIGN GATESEND-TO-END CABLE DESIGN GATESIbloadIndeviceIzIt × applicable factorsphysical method · exact table · declared conditions · all design gates

Core theory

Record circuit/from/to, load and duty, phases/loaded conductors, cable standard/construction/size, route/reference method, length, factors and their sources, It/Iz, voltage drop and design limits.

Record device manufacturer/type/rating/settings, fault level, Zs/disconnection, breaking/conditional rating, adiabatic/CPC basis, terminals, neutral/harmonic assumptions and special fire/environmental requirements.

Control revision, author/checker, calculation/source editions, assumptions, deviations and status. Update verified as-built length/route and link commissioning/test records without overwriting design history.

Terms, symbols, and units
TermMeaningSymbolUnit
Cable scheduleControlled record of cable selections and verification evidenceNot applicableNot applicable
RevisionTraceable version of a controlled documentNot applicableNot applicable
As-builtVerified record of what was installedNot applicableNot applicable
Worked exampleA schedule row contains only 'DB2-L1, 6 mm², 32 A'.

Assumptions: Only the stated fictional project data apply.

  1. Gap: No cable, route, length, factor, device or verification basis is reproducible.
  2. Enrich: Add design inputs, sources, results and every applicable gate.
  3. Control: Assign revision/check/status and reconcile with as-built/test evidence.

The three-field row is not an auditable cable design record.

Reasonableness check: The conclusion follows the declared function and evidence rather than a cable nickname.

Common mistakes
  • Selecting by trade name or sheath colour
  • Confusing low smoke with circuit integrity
  • Ignoring supports, joints, routes or terminations

Where this appears in practice

Competent designers coordinate electrical design with the building fire strategy, system standard, product certification and maintainable records.

SafetyFailure of a safety-service circuit during fire can endanger occupants and firefighters. Design, installation, inspection and testing require competent control.
Local code checkConfirm the building fire strategy, authority having jurisdiction, current BS 7671 and application standard (for example BS 5839, BS 5266 or BS 8519), exact tested cable/support/termination system, product certification, route, segregation, protection and documentation. Product names and LSOH labels never substitute for evidence. Isolate and prove dead before work.

Knowledge check

Should an as-built change silently replace the design value?

No. Preserve revision history and document the verified change and recalculation.

Answer: No. Preserve revision history and document the verified change and recalculation.

Practical exercise

Turn a minimal fictional schedule into a reproducible controlled record.

Summary

  • Function determines evidence
  • The tested installed system matters
  • Document every assumption

Sources and review

  • BS 5839-1:2025: Fire detection and fire alarm systems for non-domestic premises: BSI; 2025; United Kingdom
  • Approved Document B: Fire safety: UK Government; Current applicable edition and transition must be confirmed; England
  • Amendment 4:2026 impact on BS 7671: IET; 2026; United Kingdom

Editorial review date: 2026-08-22. Professional electrical review is pending.

Educational material for learning and preliminary checks. Verify current local requirements and exact equipment instructions. This lesson does not replace competent professional work.

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