Electrical Engineering
Articles
Practical guides and calculation references for design and engineering teams: organized by topic. Upcoming guides are listed in the roadmap at the bottom.
Duct Bank Design: How to Size Conduit Configurations
A practical guide to conduit quantities, sizes, and arrangements for underground duct bank systems: NEC and IEC.
Cable Schedule Fundamentals: Structure, Sizing Logic, and Standards
What goes into a proper cable schedule, the universal sizing logic, and where IEC and NEC practice genuinely diverge.
Load Summary Fundamentals: Demand Factors, Diversity, and Sizing Logic
How demand factors, diversity, and design margin work together, with a worked example and key standards differences.
How to Calculate Voltage Drop for LV Cable Runs
Single-phase and three-phase formulas, NEC and IEC limits, motor starting checks, and worked examples.
Cable Ampacity Derating: Temperature Correction and Grouping Factors
Temperature correction factors, grouping/bundling factors, installation method effects, and underground cable derating: NEC Table 310.16 and IEC 60364-5-52.
Short Circuit Current Calculations: MVA Method and Impedance Method
MVA method and impedance method for fault current: worked examples, motor contribution, equipment ratings, and NEC vs IEC differences.
Demand Load Calculation Basics: Demand Factors, Diversity and Design Load
Connected load, demand factor, diversity factor, and design margin: how they combine for transformer and switchgear sizing. With worked example.
Cable Tray Fill & Sizing: NEC and IEC Methods
NEC Article 392 and IEC practice: fill limits, tray types, selection criteria, and derating for bundled cables.
Ground Grid Design Basics: IEEE 80
Touch voltage, step voltage, soil resistivity, and grid conductor sizing for substation earthing systems.
MV/LV Distribution Design: Feeder Sizing, Fault Levels, and Selectivity
System architecture, the three feeder sizing checks, fault level calculations, selectivity methods, and NEC vs IEC differences.
Transformer Sizing and Inrush: A Practical Method
Design load, growth, derating, standard sizes, fault current, inrush, and losses, with NEC and IEC worked examples.
Transformer Application Engineering
Impedance, cooling classes (ONAN/ONAF), vector groups, inrush mitigation, and selection for distribution applications.
Harmonics & Power Quality: THD, Filters, and Resonance
Sources of harmonic distortion, THD limits per IEEE 519, passive and active filter selection, and resonance avoidance.
Load Flow & Stability Studies: A Practical Introduction
N-1 contingency analysis, voltage profiles, and transient stability: what EPCs and consultants need to know.
Grounding & Earthing System Design
TN-S, TN-C-S, TT, and IT earthing systems, NEC grounding electrode systems, and the critical difference between grounding and bonding.
Generator Sizing and Transient Response
Steady load, growth, derating, motor starting kVA, voltage dip, paralleling, and a worked 1,200 kW example.
Motor List Fundamentals: Structure, Data Requirements, and Standards
What goes into a motor list, how it drives cable and MCC design, and where IEC and NEC practice diverge.
Motor Starting & Protection Methods
DOL, star-delta, soft starter, VFD, starting current, torque characteristics, and protection considerations.
MCC Schedule Fundamentals: Structure, Feeder Sizing, and Coordination
What goes in an MCC schedule, starter types, cubicle numbering, protection settings, and form of separation.
// ROADMAP: 19 GUIDES IN PROGRESS
These guides are planned and not published yet. Titles and scope may change.
Generator Sizing & Transient Response
Step load analysis, voltage dip, frequency recovery, and standby vs prime rating selection.
UPS System Design: Autonomy, Bypass, and Battery Sizing
Double conversion vs eco mode, battery autonomy calculations, and bypass coordination for critical loads.
Data Center Electrical Architecture
Uptime Tier compliance, N / N+1 / 2N redundancy, busway vs RPP distribution, and critical load classification.
BESS Protection & Controls: PCS Coordination and DC Faults
Battery Energy Storage System protection philosophy, PCS coordination, DC fault behavior, and EMS logic.
Solar PV System Design, String Sizing, Inverter Clipping, and Grounding
DC array design, inverter selection, clipping ratio optimization, and NEC/IEC grounding schemes.
Duct Bank Thermal Design: Neher-McGrath and IEC 60287
Soil thermal resistivity, mutual heating between cables, and ampacity correction for underground duct bank installations.
Panelboard & Switchgear Layout
Clearance requirements, heat rise calculations, busbar sizing, and equipment arrangement in electrical rooms.
Electrical Room Planning
Ventilation, cable entry strategy, equipment spacing, NEC Article 110 working space, and coordination with other disciplines.
Lightning Protection & Surge Protection
Rolling sphere method, air termination design, SPD coordination, and NEC/IEC differences in lightning protection standards.
Single-Line Diagram Reading Guide
How to read and interpret an SLD: bus notation, protection symbols, equipment ratings, and what to check in a design review.
Protection Coordination: Relay Settings and Time-Current Curves
Overcurrent relay pickup and time dial settings, TCC plotting, and coordination between upstream and downstream devices.
Arc-Flash Hazard Analysis: IEEE 1584
Incident energy calculations, arc-flash boundary, PPE category selection, and mitigation strategies.
SCADA & PLC Integration for Electrical Systems
Modbus, DNP3, IEC 61850: protocol selection, redundancy, and failover logic for electrical SCADA systems.
IEC 61850 & Substation Automation
GOOSE messaging, logical nodes, substation communication architecture, and practical implementation considerations.
Zone Selective Interlocking: How It Works and When to Use It
How ZSI improves selectivity without time delay, wiring requirements, and typical application in LV switchgear.
Electrical Safety Programs: LOTO, Energized Work Permits
Lockout/tagout program elements, energized work permit requirements, and NFPA 70E / IEC 60900 compliance.
NEC vs IEC: Key Differences for Electrical Engineers
A practical cross-reference of the most important divergences across voltage levels, wiring methods, protection, and earthing.
Pre-Energization Electrical Checklist
What to verify before energizing a new installation: protection settings, insulation tests, phasing, and documentation.
Hybrid Microgrids: Diesel, PV, and BESS Integration
Load sharing, droop control, islanding detection, and protection philosophy for diesel-PV-BESS microgrid systems.