Aluminum wiring in an older home does not automatically mean the electrical system is unsafe or that every wire behind the walls has to...
What's changed in arc flash safety in 2026 - the 2024 NFPA 70E current edition, the 2026 NEC arc flash labeling mandate, November 2024 OSHA guidance, NFPA 70B updates, and what to audit now.
Complete NEC guide to bare copper ground wire: EGC sizing from Table 250.122, the 250.122(B) upsizing rule, GEC rules under 250.64, and where bare copper is required.
2026 NEC code changes in one list: arc flash labels without the 1,000 A limit, 2 VA/ft² load calc in Article 120, EV receptacle and SPGFCI rules, and more.
Electrical gutters (auxiliary gutters) under NEC Article 366: permitted uses, the 20% fill rule, 30-conductor derating and a worked sizing example.
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 with standard single-phase and three-phase sizes, sizing formulas, NEC 450.3 OCPD rules, K-factor and 6 worked examples.
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.
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 protects people from shock; AFCI protects wiring from fire. Compare how each works, NEC 2023 required locations and when a circuit needs both.
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 lists each conductor's circular mils, stranding, diameter and DC resistance at 75°C. How to read it, key values and voltage drop examples.
