Engineering Tool Kit
BS 7671 Design, Testing, Training & Compliance Suites
1. Electrical Design & Sizing
All-in-One Circuit Designer
Complete BS 7671 design engine. Calculate cable sizes, protective devices, voltage drop, and diversity for lighting, power, and ring final circuits.
Cable Sizing Suite
Automatically size standard multicore cables based on Design Current (Ib), Voltage Drop, and complex Installation Methods.
Heavy Industrial Mains
Designed for loads up to 3000A. Specify parallel single-core conductors (AWA/XLPE) with trefoil formation voltage drop logic.
Maximum Demand & Diversity
Ultimate maximum demand engine. Calculate connected load vs. maximum demand and apply BS 7671 diversity factors for DNO supply sizing.
Voltage Drop Calculator
BS 7671 Statutory Limit Verification. Calculate voltage drop across single and three-phase circuits.
Containment Fill Calculator
Ensure compliance with containment capacities. Instantly verify Conduit (40%) and Trunking (45%) sizing limits to BS 7671.
Adiabatic Equation & CPC Sizer
Calculate minimum protective conductor sizes using the BS 7671 adiabatic equation S = √(I²t)/k.
Main Earthing & Bonding Sizer
Size Main Earthing Conductors (Table 54.7) and Protective Equipotential Bonding (Table 54.8) for all earthing systems (TN-C-S, TN-S, TT) up to 2500A.
SWA Gland & Cleat Selector
Instantly specify the correct BW/CW/CX gland pack and cleat diameter for Steel Wire Armoured cables.
Motor FLA & Starter Sizing
Convert kW/HP to Full Load Amps (FLA) and specify contactors, overloads, and breakers for DOL and Star-Delta starters.
RCD Type Specifier
Select the correct RCD type (AC, A, F, or B) based on load characteristics and the risk of smooth DC fault currents.
Circuit Protection Selector
Calculate Ib and automatically select correct MCB, RCBO, or Fuse ratings. Includes Type B, C, and D magnetic trip curve guidance.
Outbuilding SWA Sizer
Garden Office & Outbuilding SWA Sizer. BS 7671 Sub-Main Load & Voltage Drop Calculator.
Cooker Circuit & Diversity
Load Sizing & BS 7671 Diversity Modeller for cooker circuits.
Electric Shower Circuit
BS 7671:2018+A3:2024 Cable Sizing & Compliance for electric showers.
2. Renewables, EV & HVAC
Solar PV & Battery Suite
Prosumer installation engine. Map roof space to kWp capacity, calculate inverter clipping ratios, and specify optimal battery storage capacities.
Solar PV AC & DC Design
BS 7671 Section 712 Compliance, String Configuration & Protection calculator.
Battery Storage (BESS)
Capacity, EPS Runtime & Financial Payback Modeller.
EV Charging & O-PEN Planner
Evaluate Section 722 earthing arrangements. Determine open-PEN detection requirements and map safe installation protocols for EV chargers.
EV Charger Load Assessment
BS 7671 Section 722 Compliance & Supply Adequacy checker.
Heat Pump Sizer
Air-Source & Ground-Source Circuit Specification for Heat Pumps.
Heating Load Profiler
Underfloor, Trace & Space Heating Specification calculator.
3. Inspection, Testing & EICR (BS 7671)
Commercial RCD Risk Assessment
Dynamic EICR Coding Engine based on Installation Type, DC Leakage, and ESF BPG4 Issue 7 logic.
EICR Observation Builder
EICR Field Observation Builder with Category, Defect, Location & C-CODE.
Digital Permit to Work Issuer
Safe System of Work (SSoW) field tool. Digitally issue, document, and track formal lock-off isolations, Sanctions for Test, and Limitations of Access.
EICR Testing Sequence
Comprehensive BS 7671 verification procedure detailing exact dead and live testing methodologies.
RAMS Document Generator
Generate professional, site-specific Risk Assessments and Method Statements (RAMS) to statutory health & safety standards.
Maximum Zs Values
Find statutory 100% and temperature-adjusted 80% Earth Fault Loop Impedance limits for MCBs, RCBOs, Fuses, and MCCBs.
Maximum Ze Evaluator
Evaluate external earth fault loop impedance (Ze) parameters against standard limits for TN-S, TN-C-S, and TT earthing systems.
Fault Current (PFC)
Instantly calculate Prospective Fault Current (PSCC & PEFC) in Amps and kA for Single and Three-Phase systems to verify switchgear ratings.
Ring Continuity (R1+R2)
Verify dead test readings. Calculate r1, r2, and R1+R2, or reverse-engineer continuity figures directly from live Zs and Ze measurements.
4. Lighting & Commercial Estimating
BS 5266 Emergency Lighting
2D layout simulator, coverage radii calculations, and battery chemistry specifier for emergency escape routes and open areas.
Lighting Layout Estimator
Interactive 2D simulator using the Lumen Method. Design standard office layouts and verify BS 5266 Open Area emergency coverage.
Commercial LED Payback Calculator
Calculate commercial lighting return on investment (ROI), annual financial savings, and CO2 footprint reduction for client proposals.
LED ROI Calculator
LED Energy Savings & ROI Commercial Lighting Upgrade Calculator.
CIBSE Lux Level Standard Guide
SLL Code for Lighting Compliance Standards checker.
Contracting Estimator
Rapid quotation engine. Calculate travel, plant hire, and bulk import materials from wholesaler spreadsheets to apply instant markups.
5. Apprentice Training & Learning
EICR Defect Classification Lab
Interactive code decision simulator. Practise assigning C1, C2, C3, and FI classifications to real-world electrical faults based on BPG4.
Cable Derating Thermal Sandbox
Mathematical visualization tool. Manipulate ambient heat, insulation, and grouping sliders to see real-time drops in cable capacity (Iz).
AM2 Readiness Simulator
Interactive NVQ Level 3 practical tool. Practise zero-tolerance Safe Isolation procedures and visual fault diagnosis to NET standards.
Apprentice Training Hub
Comprehensive knowledge base for C&G 2391 and AM2 prep. Review required test sequences, quick reference data tables, and verification field guides.
Microlearning & Flashcards
App-style fast revision tool with a 3D flipping engine. Master cable colours, statutory regulation indices, and EICR observation codes via spaced repetition.
18th Edition Mock Exam
Full 60-question dynamic exam engine mimicking real C&G 2382 assessments. Features a live timer, flagging system, and non-repeating mixed question matching.
6. General Reference & Theory
kW / kVA / Amps Multi-Converter
Rapid Single & Three-Phase Power Calculations.
kVA to Amps & Generator Sizing
Site Power, Temporary Supplies & Load Conversion.
EICR Frequency Guide
Determine the statutory testing periods and maximum intervals for commercial, industrial, and domestic electrical installations.
Star-Delta Converter
Apply Kennelly's Theorem to instantly convert between Star and Delta three-phase motor or heater bank impedances.
Power Factor Correction (kVAR)
Calculate capacitor bank sizing, determine exact amperage reduction, and verify kVA capacity recovery for industrial installations.
Ohm's Law & Power
Enter any two known values to instantly calculate Voltage (V), Current (A), Resistance (Ω), and Power (W) using standard DC/Resistive AC theory.
IP Code Calculator
Decode Ingress Protection (IP) ratings. Determine exact protection levels against solid particles, dust, and water for electrical enclosures.
7. Public Safety & Landlord Compliance
Client Success & EICR Portal
Transparent guide to electrical safety, compliance processes, and an interactive observation decoder for clients.
Consumer Unit Hazard Diagnostic
Public safety self-audit wizard. Step-by-step visual diagnostic checklist helping homeowners evaluate fuse board fire and shock risks.
Landlord Electrical Safety Advisor
Private Rented Sector (PRS) legal compliance tracker. Calculate statutory 5-year expiration dates and track strict 28-day remedial window deadlines.
Part P Notifiable Works Checker
Domestic Legal Compliance & Building Control Wizard.
EICR Guidelines Client Preparation
Essential preparation guide for clients before an EICR inspection.
About the TMUK Engineering Tool Kit
As a professional electrical contractor, ensuring strict compliance with BS 7671:2018+A3:2024 is paramount. This bespoke suite of free engineering calculators has been developed by TMUK Group Ltd to assist electricians, designers, landlords, and duty holders in verifying their installations, sizing cables accurately, and generating statutory health and safety documentation.
Our Core Engineering Suites
- Electrical Design & Sizing: Advanced tools for accurate cable sizing, voltage drop verification, and complex maximum demand calculations for domestic, commercial, and industrial sites.
- Renewables, EV & HVAC: Dedicated Solar PV, Battery Storage, EV Charging, and Heat Pump planners.
- Inspection, Testing & EICR: Essential resources for verifying Earth Fault Loop Impedance (Zs), Prospective Fault Current (PFC), Ring Final Continuity testing, EICR Defect Classification, and digital Permit to Work (PTW) generation.
- Lighting & Commercial Estimating: Commercial calculators tailored for generating immediate LED return on investment (ROI) proposals, BS 5266-1 emergency lighting layouts, and rapid project quoting.
- Apprentice Training & Learning: Interactive test and exam engines designed to prepare electrotechnical learners for the City & Guilds 2382 exam, C&G 2391 assessment structures, and the rigorous AM2 practical verification bay.
- General Reference & Theory: Quick calculators for Ohm's Law, Star-Delta conversion, IP codes, and kVA conversions.
- Public Safety & Landlord Compliance: Guided diagnostic trackers to ensure properties meet the statutory requirements of the Private Rented Sector (PRS) regulations and basic consumer unit safety standards.
How to Use the Dashboard
Simply select the required engineering module from the grids above to launch the application. Each tool is designed to function flawlessly on mobile devices, allowing our field engineers, qualified supervisors, and apprentice learners to perform complex mathematical verifications or access study resources directly on-site without relying on signal-dependent cloud software.