Practical guides and calculation references for design and engineering teams — organized by topic. Dimmed cards are in progress.
A practical guide to conduit quantities, sizes, and arrangements for underground duct bank systems — NEC and IEC.
What goes into a proper cable schedule, the universal sizing logic, and where IEC and NEC practice genuinely diverge.
How demand factors, diversity, and design margin work together — with a worked example and key standards differences.
Single-phase and three-phase formulas, NEC and IEC limits, motor starting checks, and worked examples.
Temperature correction factors, grouping/bundling factors, installation method effects, and underground cable derating — NEC Table 310.16 and IEC 60364-5-52.
MVA method and impedance method for fault current — worked examples, motor contribution, equipment ratings, and NEC vs IEC differences.
Connected load, demand factor, diversity factor, and design margin — how they combine for transformer and switchgear sizing. With worked example.
NEC Article 392 and IEC practice — fill limits, tray types, selection criteria, and derating for bundled cables.
Touch voltage, step voltage, soil resistivity, and grid conductor sizing for substation earthing systems.
System architecture, the three feeder sizing checks, fault level calculations, selectivity methods, and NEC vs IEC differences.
Impedance, cooling classes (ONAN/ONAF), vector groups, inrush mitigation, and selection for distribution applications.
Sources of harmonic distortion, THD limits per IEEE 519, passive and active filter selection, and resonance avoidance.
N-1 contingency analysis, voltage profiles, and transient stability — what EPCs and consultants need to know.
Substation grids, building earthing, TN-S vs TT systems, touch and step voltage, and soil resistivity testing.
What goes into a motor list, how it drives cable and MCC design, and where IEC and NEC practice diverge.
DOL, star-delta, soft starter, VFD — starting current, torque characteristics, and protection considerations.
What goes in an MCC schedule, starter types, cubicle numbering, protection settings, and form of separation.
Step load analysis, voltage dip, frequency recovery, and standby vs prime rating selection.
Double conversion vs eco mode, battery autonomy calculations, and bypass coordination for critical loads.
Uptime Tier compliance, N / N+1 / 2N redundancy, busway vs RPP distribution, and critical load classification.
Battery Energy Storage System protection philosophy, PCS coordination, DC fault behavior, and EMS logic.
DC array design, inverter selection, clipping ratio optimization, and NEC/IEC grounding schemes.
Soil thermal resistivity, mutual heating between cables, and ampacity correction for underground duct bank installations.
Clearance requirements, heat rise calculations, busbar sizing, and equipment arrangement in electrical rooms.
Ventilation, cable entry strategy, equipment spacing, NEC Article 110 working space, and coordination with other disciplines.
Rolling sphere method, air termination design, SPD coordination, and NEC/IEC differences in lightning protection standards.
How to read and interpret an SLD — bus notation, protection symbols, equipment ratings, and what to check in a design review.
Overcurrent relay pickup and time dial settings, TCC plotting, and coordination between upstream and downstream devices.
Incident energy calculations, arc-flash boundary, PPE category selection, and mitigation strategies.
Modbus, DNP3, IEC 61850 — protocol selection, redundancy, and failover logic for electrical SCADA systems.
GOOSE messaging, logical nodes, substation communication architecture, and practical implementation considerations.
How ZSI improves selectivity without time delay, wiring requirements, and typical application in LV switchgear.
Lockout/tagout program elements, energized work permit requirements, and NFPA 70E / IEC 60900 compliance.
A practical cross-reference of the most important divergences across voltage levels, wiring methods, protection, and earthing.
What to verify before energizing a new installation — protection settings, insulation tests, phasing, and documentation.
Load sharing, droop control, islanding detection, and protection philosophy for diesel-PV-BESS microgrid systems.