Branch Circuit Types Explained: General Purpose, Appliance & Individual
Complete guide to branch circuit types — general purpose, appliance, individual, and multiwire. NEC 210.23 permissible loads, the 80% and 50% rules, ratings, and worked examples.
Transformer kVA Rating Chart: Standard Sizes & Sizing Guide
Transformer kVA rating chart with standard single-phase and three-phase sizes, sizing formulas, NEC 450.3 OCPD rules, K-factor and 6 worked examples.
NEC Code Book Editions: 2017 vs 2020 vs 2023 vs 2026 Differences
The NEC is updated every 3 years: 2017, 2020, 2023, 2026 (next: 2029). Key changes in each edition, which states use which, and which to study for your exam.
Electrical Room Signage: NEC & NFPA Requirements for Panels & Equipment
Complete guide to required electrical room signage — NEC 110.21, arc flash labels (110.16), fault current marking, available fault current, working clearance signs, and OSHA requirements.
GFCI vs AFCI: Differences & Where Each Is Required
GFCI protects people from shock; AFCI protects wiring from fire. Compare how each works, NEC 2023 required locations and when a circuit needs both.
Intersystem Bonding Termination: What It Is & NEC Requirements
Complete guide to intersystem bonding terminations (IBT) under NEC 250.94 — the six IBT conditions, other means option, where to install, which systems require bonding, and 2023 changes.
NEC Chapter 9 Table 8 Explained: Conductor Properties Guide
NEC Chapter 9 Table 8 lists each conductor's circular mils, stranding, diameter and DC resistance at 75°C. How to read it, key values and voltage drop examples.
High Voltage Cable: Types, Ratings & NEC Installation Requirements
When electricians search "high voltage cable," they are almost always looking for what the NEC and the electrical industry technically classify as medium voltage (MV)...
Florida Electrical Contractor License Requirements
To work as an electrical contractor in Florida, you need to understand the difference between a certified statewide license, a registered local license, and...
Grounding vs Bonding Bushings: When the NEC Requires Each
Bonding bushing vs grounding bushing: when NEC 250.92 and 250.97 require one, the 250 V-to-ground rule, and how to size the bonding jumper on the bushing.
Pull Box Sizing: NEC 314.28 Rules, Chart & Exam Examples
Straight pull = 8× the largest raceway; angle or U-pull = 6× plus the others. Free NEC 314.28 pull box sizing chart and worked exam examples.
Multi-Wire Branch Circuits: NEC Code Rules & Safety Requirements
A multi-wire branch circuit shares one neutral between 2 or 3 hots. NEC 210.4 rules: same-panel origin, simultaneous disconnect, handle ties, neutral pigtails.
