The PEC Blog

Plain-English explanations of NEC rules, calculation methods, and field tips — written by a working Arkansas electrician. Each article links to the calculator that can run the numbers for you.

June 14, 2026 Calculator Guide
Voltage Drop Explained: The 3% and 5% Rules
What NEC 210.19(A) and 215.2(A) actually say about voltage drop, why it matters, and how to check your circuit.
June 14, 2026 Calculator Guide
Conduit Fill Rules: 1, 2, or 3+ Conductors
Why the NEC fill percentage changes depending on how many wires you're pulling.
June 14, 2026 Calculator Guide
NEC 314.16 Box Fill, Broken Down
A plain-English walkthrough of how conductors, devices, clamps, and grounds count toward box fill.
June 14, 2026 Calculator Guide
Ampacity and Temperature Correction Explained
Why the ampacity printed on the wire jacket isn't always the ampacity you can actually use, and how NEC 310.15 correction factors work.
June 14, 2026 Calculator Guide
Transformer Sizing 101
How to size primary OCPD, calculate FLA, and understand turns ratio for single and three phase transformers.
June 14, 2026 Calculator Guide
Motor FLA vs. Nameplate Amps
Why the NEC tables in Article 430 — not the motor's nameplate — drive your circuit sizing.
June 20, 2026 Question Corner
AFCI vs GFCI: What's the Actual Difference
Fire protection vs shock protection — what each device detects and where the NEC requires them.
June 20, 2026 Question Corner
Grounding vs Bonding Explained
Two different jobs that often get treated as one. A clear breakdown per NEC Article 250.
June 20, 2026 Question Corner
Schedule 40 vs Schedule 80 PVC Conduit
Wall thickness, fittings, and where each schedule actually belongs on the job.
June 20, 2026 Question Corner
Facts About Bending EMT
Take-up numbers, offset multipliers, and bend limits for a clean rough-in.
June 20, 2026 Question Corner
Load Calculations Explained
How demand factors and the Optional Method work for dwelling unit service sizing.
June 20, 2026 Question Corner
Control Wiring Explained
Control voltages, color conventions, and ladder diagrams for motor and equipment controls.
June 20, 2026 Question Corner
Commercial/Industrial vs Residential Work
How voltage, wiring methods, and load types actually differ across these settings.
June 20, 2026 Question Corner
Tandem Breakers: When They're Allowed and When They're Not
Why tandem breakers fail inspections constantly, and the one check that prevents it.
June 28, 2026 Calculator Guide
Ohm's Law Explained: Voltage, Current, Resistance, and Power
All 12 Ohm's Law formulas, what each variable means, and how to use them in the field.
June 28, 2026 Calculator Guide
Ground Wire Size Explained: NEC Table 250.122
How to size equipment grounding conductors per NEC Table 250.122, and when to upsize per 250.122(B).
June 28, 2026 Calculator Guide
Circuit Breaker and Fuse Sizing Explained
NEC sizing rules for general loads, motors, HVAC, and welders — Articles 210, 430, 440, and 630.