Electrical Engineering Studio

NEC 220 load calculation, panel schedule with AFCI/GFCI, single-line diagram, voltage drop (K-factor), grounding worksheet (NEC 250), and permit-ready package.

Form-driven NEC 220 Part III/IV designer for offices, industrial, campus, retail, healthcare, data centers and more — lighting/receptacle/HVAC/motor (430)/kitchen (220.56) loads, 3-phase service, step-down transformer (450), panelboards, emergency/standby (700/701/702), fire pump (695), grounding (250), and a permit-ready package.

IEEE 551 short circuit study, protection coordination, ground grid (IEEE 80), arc flash (IEEE 1584), single line diagram, equipment schedule, and permit package.

Freehand drag-and-drop CAD-style tool — place outlets, switches, lighting, ceiling fans, smoke detectors, panels, and junction boxes on a room outline, move/delete with undo-redo, and get a live device schedule plus an NEC 220.12/220.52/220.42 load estimate.

Enter motor, transformer, pump/VFD, generator, or panel nameplate data and get a linked one-line diagram (standard symbols), equipment schedule, bill of materials, and wire schedule — sized with NEC 430/450/240 conventions. Optional best-effort photo OCR pre-fill.

Interactive 3D walkthrough of a typical single-family house — service entrance, main panel, AFCI/GFCI breakers, branch circuits, lighting, smoke/CO detectors, EV charger, and low-voltage systems. Click any device for NEC code references.

Split-screen interactive designer — explore a 3D two-story dwelling alongside a live one-line / panel schematic. Click any device or schematic node to cross-highlight across both views: service entrance, branch circuits, lighting, safety, and low-voltage systems with NEC references.

Split-screen interactive designer for a 3-story commercial building — explore the 3D building alongside a live electrical one-line and floor plan. Click any device or node to cross-highlight across all three views: utility service, main switchboard, step-down transformers, floor panelboards, branch circuits, mechanical feeders, and the emergency/standby system (generator, ATS, fire pump) with NEC references.

Split-screen interactive explorer for a complete 138 kV / 13.8 kV transmission substation — 3D switchyard (lattice towers, transformers, SF6 breakers, busbars, switchgear) alongside the IEEE single-line diagram. Click any component or SLD symbol to cross-highlight and inspect the full engineering profile for all 54 components across 8 systems: primary equipment, relay protection, control, auxiliary power, grounding, communications, feeders and monitoring.

Free interactive 3D walkthrough of an industrial facility electrical system — MV service and switchgear, step-down transformers, main distribution panel, motor control centers (MCCs), VFDs, motors, and emergency power. Click any piece of equipment for NEC, IEEE, and NEMA code references.

Interactive DC + AC circuit simulator — build resistor, capacitor, inductor, LED, switch and AC/DC source circuits on a schematic and solve node voltages, branch currents, and power with live nodal analysis (MNA), plus AC steady-state phasor analysis with a live dual-channel oscilloscope. Includes voltage divider, RC filter, and Wheatstone bridge presets.

A full PCB design studio in your browser — component reference library, parametric templates, a plain-English design generator, and a multi-layer CAD editor with a Lee wave-propagation autorouter, Design Rule Check, and Gerber / KiCad / SVG / BOM export. No account or API key required.

Plot time-current curves (TCC) on a log-log diagram for upstream and downstream breakers. Adjust trip settings and verify selectivity — see exactly where coordination fails.

Assign circuits to Phase A, B, or C in an interactive 3-phase panel. Watch live phase totals and percent imbalance update as you build the schedule.

Animate inrush current, voltage dip, and speed ramp for DOL, star-delta, and VFD motor starts. Adjustable HP, kVA, and system impedance.

Interactive kW/kVAR/kVA power triangle. Stage capacitor bank steps and watch PF, apparent power, and estimated demand charge savings update in real time.

Apply 3-phase, line-to-line, and line-to-ground faults at any bus in a simple distribution system. Trace fault current path and watch the upstream breaker trip sequence.

Walk through a complete NEC 220 residential or small-commercial load calculation step by step. Each stage shows the applicable code section and running service-entrance total.

NEC 220 residential and commercial demand load calculation. Determines service entrance size and total connected load with demand factors.

Calculate conductor voltage drop per NEC 210.19. Verifies branch circuits and feeders stay within the recommended 3% (5% total) drop.

Verify conduit fill compliance per NEC Chapter 9, Table 1. Supports EMT, RMC, IMC, PVC, and LFNC with multiple conductor types and sizes.

NEC 310.15 conductor ampacity with temperature correction and bundling derating factors. Covers THWN, XHHW, USE-2, and more.

Calculate available fault current at the transformer secondary using impedance method. Determines minimum interrupting rating for breakers and fuses.

IEEE 1584 arc flash analysis. Calculates incident energy (cal/cm²), PPE category, arc flash boundary, and required working distance.

NEC 430 full sizing for motor branch circuits — conductor ampacity, overcurrent protection, overload relay, and disconnecting means.

Balance circuit loads across Phase A, B, and C in a 3-phase panel. Calculates phase totals, percent imbalance, and total panel demand.

Size standby and emergency generators based on connected loads, demand factors, and motor starting kVA. Recommends standard generator kW rating.

Calculate required transformer kVA for single-phase and three-phase systems. Applies demand factors and selects from standard ANSI/IEEE kVA ratings.

Determine the capacitor bank size (kVAR) needed to correct power factor to a target value. Reduces apparent power and utility demand charges.

Size equipment grounding conductors (EGC) and grounding electrode conductors (GEC) per NEC 250.122 and 250.66 based on OCPD rating.

Solve for voltage, current, resistance, or power given any two known values. Includes full V/I/R/P formula reference table.

Calculate output voltage, current, and power dissipation for a resistive voltage divider. Includes SVG circuit diagram.

Interactive NEC Table 310.16 lookup with ambient temperature correction factor and conduit fill derating. Cu and Al, all gauges.

Screen a solar, wind, or BESS project against FERC SGIP fast-track criteria — circuit peak load %, reverse power flow/voltage rise, and IEEE 1547-2018 ride-through/anti-islanding requirements.

Size a substation station-service DC battery bank with a simplified IEEE 485 duty-cycle method — required ampere-hour capacity and recommended series cell count for 48V/125V/250V control power.

Check mast or shield-wire shielding of substation equipment using the NFPA 780 / IEEE 998 rolling sphere method — protected radius at ground and at equipment height, with a shielded/exposed check.

Size a UPS for a data center, server room, or critical load — required kVA rating from connected kW, output power factor, and a derating margin, plus a rough VRLA vs Li-ion battery runtime estimate.

Point-to-Point Method short-circuit study for radial single-source systems — transformer secondary fault current plus downstream conductor impedance, to verify equipment AIC/withstand ratings.

Educational primer on protective device coordination — time-current curve concepts, the coordination margin rule of thumb, selective vs. non-selective coordination, and why real studies need manufacturer trip-curve data.

Educational NFPA 70E arc-flash awareness guide — incident energy analysis vs. the PPE Category Method, the 4 PPE categories, approach boundaries, and why the equipment label is authoritative. Not a numeric PPE calculator.

Overhead conductor sag using the parabolic approximation D = wS²/(8T) — enter unit weight, span, and tension (or %RBS), then check ground clearance against your jurisdiction's required value.

Peek's formula for the fair-weather critical disruptive (corona onset) voltage of a transmission conductor — conductor radius, spacing/GMD, and air density factor, compared against system phase voltage.

Simplified IEEE 80 substation ground grid resistance (Sverak's formula) plus tolerable touch/step voltage limits (50 kg body) from soil resistivity, grid area, burial depth, and fault clearing time.

Peukert's Law battery discharge calculator — enter rated capacity, rated hours, actual load current, and a Peukert exponent to find real discharge time vs. the naive C/I estimate.

Size a battery charger from a known discharge event — Ah used, a 10% charge-inefficiency margin, and required recharge current for a desired recharge window.

NEC Table 314.16(B) box fill volume calculation — conductor counts by gauge plus clamp, device/yoke, and grounding conductor allowances, checked against a standard or custom box size.

Size the grounding electrode conductor / main & supply-side bonding jumper per NEC Table 250.66 from the largest service conductor, copper or aluminum, plus a telecom/TIA-607 bonding-length note.

How every electrical license exam works and how they relate — the FE and PE (Power, Electronics/Controls/Comms, Computer) engineering path and the electrician trade ladder (journeyman → master → contractor). Requirements, exam formats, references allowed, and study strategies.

Fundamentals of Engineering — the first step toward a PE license. Practice problems and review across circuits, electronics, digital systems, power, signals, and engineering economics.

150 original questions going deeper than the free exam above — trickier multi-step calculations, subtler concept distinctions, and more application-level scenarios across the same NCEES topic outline. Instant online access, good for 90 days.

Depth-exam prep for power-system engineers — distribution, transformers, motors, protection & coordination, fault analysis, grounding, and NEC/NESC/IEEE codes.

Depth-exam prep covering analog/digital electronics, control systems, communications theory, signal processing, and instrumentation.

Depth-exam prep for computer hardware and embedded systems — digital design, computer architecture, embedded systems, networks, and hardware/software interfacing.

NEC-based trade exam prep — fast code lookup, conductor and box/conduit fill, branch-circuit and feeder sizing, motor calculations, grounding & bonding, and electrical theory.

Advanced NEC application, load and service calculations, plan review, and supervisory knowledge for the master electrician license.

Trade plus business & law prep for the contractor license — estimating, project management, contracts and liens, labor/safety regulations, insurance, and bonding.

Limited-scope residential license prep — dwelling load calculations, AFCI/GFCI, service and panel installation, branch circuits, and grounding for one- and two-family dwellings.

Limited-energy license prep — Class 2/3 circuits, structured cabling, fire alarm (NFPA 72), security and access control, and communications (NEC Chapter 8).

Practice for the IBEW/NJATC electrical apprenticeship aptitude test — algebra & functions and reading comprehension sections. 50 original questions mirroring the real exam format.

Entry-level NCCER practice exam — Core Curriculum (OSHA safety basics, construction math, hand & power tools, blueprint reading, rigging, employability) plus Electrical Level 1 (electrical theory, safety, intro to the NEC, device boxes, hand bending, raceway & fittings, conductors, drawings, and residential services).