NEC-based tools for wire sizing, voltage drop, conduit fill, load calculations, and recessed lighting layout.
All calculations reference NEC 2023 tables. For critical installations, always verify with a licensed electrician.
Find the minimum wire gauge for a given load based on NEC Table 310.12. Applies 80% continuous load factor when selected.
Reference: NEC 310.12, Table 310.12(A/B). Assumes 3 current-carrying conductors, no additional derating.
Calculate voltage drop and percentage for a conductor run. NEC recommends ≤3% for branch circuits and ≤5% total (feeder + branch).
Formula: VD = (K × I × D × 2) / CM for single phase; × √3 factor applied for three phase. K = 12.9 (Cu), 21.2 (Al).
Verify NEC conduit fill compliance per Chapter 9 Table 1. Max fill: 53% (1 wire), 31% (2 wires), 40% (3+ wires).
Reference: NEC Chapter 9, Table 1 & Table 4. Wire areas from Table 5 (THHN/THWN-2).
Estimate service size using the NEC Article 220 standard (general) calculation method for dwelling units.
Reference: NEC Article 220, Part III. Standard calculation method. Consult a licensed electrician for final service sizing.
Enter your room size, pick a layout pattern, and instantly get a to-scale ceiling plan with exact fixture positions and spacing measurements — plus wiring recommendations from our electricians.
Click any pattern to select it. The diagram updates instantly once room dimensions are entered.
Key rule: wall-to-first-fixture = fixture spacing ÷ 2. Spacing along each axis = room dimension ÷ number of fixtures in that direction. Based on IES illuminance recommendations and NEC 210.23 branch circuit loading. Need a licensed electrician to install? Get a free quote →