CableSpec Pro is the professional-grade evolution of CableSpec - purpose-built for M&E design offices and large contractors. Every BS 7671 Appendix 4 check on every circuit, plus the complete distribution network: boards, sub-mains, cumulative voltage drop, selectivity advisory, bulk import and a REST API.
Modern M&E design involves hundreds of circuits across multiple distribution boards, sub-mains and switchrooms. Tracking accumulated voltage drop, checking selectivity between devices and keeping board schedules up to date can't be done in a single-circuit tool or a spreadsheet.
Auto-select the minimum compliant cable size, or verify a size you have already specified.
Compare cable types, installation methods and protective devices side by side on any circuit.
Define cable routes to calculate BS7671 grouping factors (Cg) automatically for every circuit on the route.
Per-circuit calculation certificates and full project schedules with your company branding.
Share read-only project summaries with clients and reviewers. No login required.
Define boards, sub-mains and final circuits. Track feeding relationships and accumulated VD from origin.
Hierarchical board schedule with ΣVD per circuit. Auto-generated single-line distribution network diagram.
Import hundreds of circuits from a filled Excel template. Parse, preview errors, then calculate all in one step.
Energy (I²t) and current selectivity checks between upstream and downstream protective devices per Reg 536.4.
Bearer token API for Revit plugins, Power Automate flows and custom integrations, with OpenAPI and in-app documentation.
CableSpec Pro is structured around the distribution network as a whole - not just individual circuits. Define your boards, assign circuits, track accumulated VD and generate the full hierarchy of documentation a major project requires.
Create the project with supply parameters, then define distribution boards and their feeding relationships. Import circuits in bulk from an Excel template or add them individually - each assigned to a board and feeding sub-main.
Run the BS7671 engine across all circuits, with upstream sub-main impedance carried into every downstream Zs and fault current. Review accumulated VD from origin through sub-mains to final circuits. Check selectivity between upstream and downstream devices. View the live network diagram.
Download hierarchical board schedules, per-circuit PDF certificates, the distribution network diagram and a full project report. Send results to Revit or downstream tools via the REST API.
Enter Ib, device and run length and CableSpec works up through the available cable sizes to find the smallest that passes every check. If no size passes, it tells you which check is failing, the smallest size that meets capacity and voltage drop, and what would fix it — an RCD, a lower device rating or a bigger CPC.
Already have a cable size specified? Enter it and Verify mode checks it against every BS7671 Appendix 4 check. Useful for design reviews, checking a size chosen for other reasons, and existing installations.
Run alternative calculations on the same circuit with different cable types, installation methods or protective devices. Compare results side by side to find the most efficient or practical option.
Every calculation is saved as a numbered, timestamped version with its results, the engineer who ran it, the mode and the amendment. Reopen any earlier version to see how the design evolved — useful for CDM, design reviews and revisits.
Define cable routes with one of 11 arrangements — bunched, enclosed, clipped, trays, ladder, buried direct or in ducts. CableSpec looks up the BS7671 grouping factor (Cg) for the number of circuits on the route, and flags every circuit on it for recalculation when the route changes.
Organise work by project, each with its own supply parameters. Bulk recalculate all circuits in a project after changing Ze or earthing type. Project dashboard shows instant pass/fail/pending status at a glance.
Professional A4 PDF for each circuit: all inputs, every correction factor, each check result with its regulation reference, step-by-step VD and Zs working, prospective fault current, and an engineer declaration with name, date and your saved signature.
Print-ready A4 landscape circuit schedule showing all key results across the project. Full project PDF with a compliance summary, project details, engineer declaration and the circuit schedule. CSV export for external processing.
Share a read-only view of any project with clients, principal designers or reviewers. Links last 30 days, need no login on the receiving end, and can be revoked at any time from your project view.
Upload your company or organisation logo. It appears automatically on certificates, reports, board schedules, network diagrams and client share pages, replacing the CableSpec wordmark with your own identity.
Every result is stamped with the BS7671 amendment in force when the calculation was run. Circuits calculated under a previous amendment are flagged on the project view, certificate and share page.
Changed Ze or earthing system after preliminary design? One click re-runs the engine across all circuits in a project, preserving each circuit’s mode (design or verify) and showing a pass, partial and fail summary on completion.
Define distribution boards and their feeding relationships. Each circuit is assigned to a board and (optionally) fed by an upstream sub-main. The full network structure is stored, navigable and used for ΣVD tracking.
Tracks voltage drop from the supply origin through every sub-main to each final circuit per BS7671 Appendix 4 §6.4. Shows the full VD chain, own VD vs ΣVD, remaining budget and colour-coded pass/warn/fail status.
Printable A4 landscape board schedule organised by board hierarchy. Board headers with sub-totals, per-circuit own VD and ΣVD columns, feeding chain indicator, binding constraint column and CSV export.
Energy (I²t) and current selectivity checks between each circuit’s device and the device feeding it, per Reg 536.4. Returns discriminates / partial / fails / unknown with engineering notes. Advisory only - does not affect pass/fail status.
Download the import template, fill in your circuit data (28 columns), upload and preview. Valid rows are inserted and calculated immediately. Board, feeding sub-main, device and conductor size can all be set from the sheet. Parse errors shown per row before commit.
Auto-generated single-line distribution network diagram rendered as SVG. Supply origin, main boards, sub-boards and final circuits with device symbols, cable sizes and status colour coding. A3 PDF and SVG export.
Full REST API with scoped bearer token authentication. Create circuits for immediate BS7671 calculation, read projects, schedules and results, and look up reference data. Rate limiting, a request log and per-key scope control built in.
CableSpec Pro holds current-carrying capacity, mV/A/m and conductor resistance data for over 30 UK cable types, from BS7671 Appendix 4 tables — with manufacturer data for fire-resistant and mineral insulated cables, where BS7671 has no table. Single-phase and three-phase ratings are held separately.
PVC and LSF flat twin & earth and 3-core & earth, 1–16mm². Methods A, B, C and 100–103 (cables in insulated walls, floors and ceilings). Twin & earth is single-phase only.
70°C 6491X and 6181Y, 90°C 6181XY and LSF 6491B singles, 1–300mm². Methods A, B and C in conduit or trunking, and F in free air from 25mm².
70°C PVC and LSF and 90°C XLPE circular multicore, 1–300mm². Methods A, B, C and E.
70°C PVC and LSF and 90°C XLPE SWA, 2-core and 3/4-core, 1.5–300mm². Methods C, E, D1 and D3 (buried direct and in ducts). The armour is checked as the CPC.
90°C XLPE SWA with aluminium conductors, 2-core and 3/4-core, 16–300mm². Methods C, E and D1. Common for DNO feeders and large sub-mains.
PVC-sheathed light duty (1.5–4mm²) and heavy duty (1.5–25mm²) mineral insulated cable, methods C and E. Inherently fire resistant.
FP100, FP200, FP200 Gold, Fireforce PH30 and FP400 armoured, rated from manufacturer data. Used for emergency lighting, fire alarm and life-safety circuits.
60°C PVC flexible cords 3182Y–3185Y (0.5–4mm²) and H07RN-F rubber flexible (1–50mm²), methods C and E. Cords without a CPC are blocked where fault protection is needed.
CY (tinned copper braid screened), SY (steel wire braid) and YY (unscreened) flexible cables, 0.5–6mm², rated conservatively as 60°C cords. Used for instrumentation and machine wiring.
CableSpec Pro is designed for M&E consultants, large contractors and design offices who produce compliant cable schedules for complex, multi-board installations - not single circuits, but complete distribution networks.
CableSpec Pro gives your cable sizing calculations the rigour they deserve - every Appendix 4 check, full correction factor working, and a professional PDF certificate per circuit.
Produce the cable schedules, project reports and client documents that tenders, IET Wiring Regulations Part 6 and CDM documentation require - without spreadsheet errors or missing checks.
CableSpec Pro gives design offices the hierarchy they actually work with - boards, sub-mains and final circuits - with all the documentation a design submission or O&M pack requires.
CableSpec Pro is part of the Construct Software product suite - specialist applications for the UK electrical contracting and building services sector. Single sign-on across all products.
Compliance management: PAT, Minor Works, EICRs, PTW, compliance calendar and document management.
Structured interim electrical safety inspections. Locked PDF reports and secure client share links.
Produce compliant Electrical Installation Certificates, Minor Works Certificates and Condition Reports to the latest wiring regulations.
Full-stack FM for planned maintenance, reactive jobs and asset management across portfolios.
Insurance, accreditation and credential tracking for contractors working on your sites.
Temporary electrical system certification to BS 7909 for events, media and entertainment.
Electrical and Mechanical Toolbox - engineering calculation tools for building services design.
The Construct Software suite continues to grow. New tools added regularly across the industry.
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CableSpec Pro is licensed annually per organisation. All seven Pro features - distribution network, board schedule, network diagram, accumulated VD, selectivity advisory, bulk import and REST API - are included as standard with no add-ons.
Annual subscriptions. All prices exclusive of VAT. Full pricing details →
Everything you need to know before getting started with CableSpec Pro.
CableSpec Pro brings BS7671 Appendix 4 rigour to every cable sizing decision - and extends it to the complete distribution network: accumulated VD from origin, selectivity advisory, hierarchical board schedules and a REST API for BIM integration.