Checklist · Free
Code Reference Hub
Electrical, plumbing and HVAC field lookups with code citations — links to our calculators.
Citations are references only — we do not reproduce code text. The authority having jurisdiction and local amendments govern.
- Box fill
NEC Ch. 314 — volume allowances
- Conduit fill
NEC Ch. 9 — conduit fill tables
- Wire ampacity
NEC 310 — ampacity and derating
- Voltage drop
NEC 210.19(A) — branch circuit performance
What this assumes
- Illustrative defaults — replace with your actual costs and local rules.
Understanding the result
How to use this
Electrical, plumbing and HVAC field lookups with code citations — links to our calculators.
Common questions
Is this free?
Yes — runs in your browser, no account required.
You may also need
The next decision usually follows directly from this one.
- CalculatorConduit Fill CalculatorCheck conductor fill against NEC Chapter 9 limits and find the trade size you need.
- CalculatorBox Fill CalculatorCount conductor volume allowances to confirm a device box is legally large enough.
- CalculatorDrain & Vent Size CalculatorSize drain, waste and vent piping from drainage fixture unit loads and slope.
- CalculatorDuct Size CalculatorSize round and rectangular duct from airflow and friction rate, with velocity checks.