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).
A complete dwelling-unit load calculation using both methods the NEC permits: the Standard method (Article 220, Part III) and the Optional method (220.82). Check what the home has, adjust nameplate values if you know them, and you get an itemized worksheet you can print, save as PDF, or email.
Count electric ranges, cooktops and wall ovens. Table 220.55 applies a demand factor — you do not add the full nameplate.
Count every electric dryer in the home. At five or more, Table 220.54 applies a demand factor — you do not add each full nameplate.
These are noncoincident loads — the NEC lets you count only the larger of the two, since they do not run at the same time. Enter both and the calculator keeps whichever governs.
Check what the home has. The VA values are typical — change any of them if you have the equipment nameplate. With four or more of these fastened-in-place appliances, the NEC permits a 75% demand factor.
Reference: NEC Article 220 — Part III (standard method), 220.82 (optional method for dwellings), Table 220.42 (general load demand factors), Table 220.55 (cooking equipment), 220.54 (dryer), 220.53 (fastened-in-place appliances), 220.60 (noncoincident loads), 220.57 (EV charging) and 430.24 (25% of the largest motor). This sheet is a working document: to submit it for permit or inspection, a licensed electrical contractor must review it, sign it, and verify actual nameplate values on site.
The customer receives the full worksheet on company letterhead. A copy goes to the office.
Estimate the standby generator size your home needs. In Southwest Florida, air conditioning is almost always the load that decides the size — it starts with a surge far above what it draws while running, and that surge drives most of the math.
Add each system separately — up to four. Leave any you do not have set to “None.”
Check only what runs on electricity. If it runs on gas, leave it unchecked — it draws nothing from the generator.
This is a planning estimate, not a final sizing. Wattages are typical values — your actual equipment may differ, and your AC compressor nameplate governs. Final sizing requires an on-site load calculation, verification of gas line pressure and pipe size, and permitted clearance distances. Reference: NEC Article 702 (optional standby systems) and 220 (load calculation).
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 →
