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.

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.

Conduit Fill Rules: 1, 2, or 3+ Conductors

Why the NEC fill percentage changes depending on how many wires you're pulling.

NEC 314.16 Box Fill, Broken Down

A plain-English walkthrough of how conductors, devices, clamps, and grounds count toward box fill.

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.

Transformer Sizing 101

How to size primary OCPD, calculate FLA, and understand turns ratio for single and three phase transformers.

Motor FLA vs. Nameplate Amps

Why the NEC tables in Article 430 — not the motor's nameplate — drive your circuit sizing.