Fast, transparent BS 7671 calculators that show their step-by-step mathematical working — paired with interactive 3D WebGL plant machinery you can orbit and pull apart in real time. 100% free, plant-room ready.
An actively growing engineering workstation built by a working UK electrical engineer. New 3D models and sizing engines added regularly.
Interactive 3D electromagnetics and machinery. Part of a growing first-principles suite with new industrial modules continuously in development.
Cutaway, exploded and X-ray views. Change frequency, poles and load, and watch slip open up between synchronous and rotor speed.
Launch Interactive Lab →Sinusoidal PWM carrier wave synthesis, 6-IGBT inverter bridges, DC bus filtering, and transmission line dV/dt reflection spikes.
Launch Interactive Lab →Core balance CT flux cancellation and high-speed polarized flux-opposing relay. Step through real-world fault scenarios and DC blinding.
Launch Interactive Lab →Every tool computes transparently from BS 7671 equations and shows its step-by-step working. Our calculation deck is continually expanded to cover new industrial and domestic scenarios.
Popular tools:Cable sizingMax ZsVoltage dropAdiabatic CPC24V DC drop
BS 7671 step-by-step cable derating with ambient, grouping, and insulation correction factors.
Full load current and starting inrush for DOL, Star-Delta, Soft Start, and VFD methods.
Real-time electricity cost per hour, shift, month, and year from rated kW and tariff.
Engineered for rapid site verification on phones and tablets. Fast lookup tables, 1-click clipboard export for inspection software, and print-ready A4 checklists.
IP ratings, Bathroom Zones, Earthing systems, and disconnection times in one pocket card.
Search 40+ classified defects and copy compliant certificate wording in one click.
Print-ready A4 site sheets for safe isolation, testing, emergency lighting, and motor QC.
Practical engineering workflows, testing procedures, and statutory regulatory breakdowns. 27 field guides live, with new compliance topics published regularly.
Section 722: 4 open-PEN routes, integral 6mA DC RDC-DD units vs Type B RCDs.
Field-tested guide to defect classification, borderline observations, and missing RCD upgrades.
10-step safe isolation cycle, neutral back-feeds, UPS supplies, and solar PV isolation safety.
Mandatory duties under EAWR 1989 Reg 14, cut-out isolation procedures, and 31 days remaining in the BS 7671:2018+A4:2026 Orange Book transition window.
Key Takeaway: NAPIT advises on rectifying live defects found during pre-tender site visits and interpreting relevant EICR codes.
NAPIT’s technical team is reviewing a live electrical installation discovered during a pre-tender site visit for a refurbishment project. The article provides advice on interpreting the associated EICR codes and outlines the necessary next steps for rectifying the observed defects.
