Trade guides
The reasoning behind the calculators — electrical, HVAC, and plumbing sizing explained in plain English.
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Electrical
NEC Wire Size Chart: Complete Ampacity ReferenceCopper and aluminum ampacity by AWG, in one lookup table.
How to Read a Wire Gauge ChartWhat AWG numbers mean and why smaller numbers are thicker wire.
Voltage Drop Explained: NEC Limits and Why They ExistThe reasoning behind the 3%/5% recommended limits.
12 AWG vs 10 AWG Wire: What's the DifferenceAmpacity, cost, and when each size is the right call.
Copper vs Aluminum Wire: Sizing Differences ExplainedWhy aluminum needs a larger gauge for the same load.
Single-Phase vs Three-Phase Wiring ExplainedWhat the difference means for sizing and voltage drop.
Common Wire Sizing Mistakes (and What They Cost You)The most frequent errors and how to catch them early.
When to DIY vs Call a Licensed ElectricianA practical line between safe DIY work and hiring a pro.
NEC Conduit Fill Rules ExplainedWhy 53%/31%/40%, and how fill rules differ from ampacity derating.
Understanding NEC DeratingThe full temperature and conductor-bundling correction tables, explained.
HVAC
BTU vs Tonnage ExplainedWhy 12,000 BTU equals 1 ton, and how to convert between them.
Understanding SEER RatingsWhat SEER measures, SEER vs SEER2, and what counts as a good rating today.