Free Load Analysis Tools · NEC 220.87 · 120.87 in the 2026 Code

Headroom Check: For When the Load Calc Says No.

The Article 220 calculation runs high on older buildings by design. Before you quote a service upgrade, run the recorded-data math: enter the service, the real peak, and what you are adding. Free, no sign-up, printable.

SITE & PROPOSED LOADSINPUTS

Site / panel (for the printout)

Service or feeder rating (A)

System voltage

Known peak demand (A)

Where that peak comes from

On this service

Solar PV, wind, or any other generationBattery or any form of peak load shaving

Either one takes the 30-day recording off the table, because the meter reads net rather than load.

Proposed added loads

cont.

Amps are computed from kW at the selected system voltage. Three-phase: kW × 1000 ÷ (1.732 × V). Enter nameplate kW. Anything ticked cont. is counted at 125 percent, which is how Article 220 treats a load running three hours or more.

220.87 HEADROOM CHECKAug 25, 2026

Site800 A · 480Y/277 V · 3Φ

Peak demand × 125%515 A

Proposed loads, continuous at 125%+ 69 A (46 kW)

Projected total vs rating584 A of 800 A

Existing at 125%Proposed

HEADROOM: 216 A

Looks like it clears, on an estimate, which proves nothing to a plan reviewer. 220.87 requires a year of demand data or a 30-day recording. The load study is that proof.

Order the 30-day Load Study

A pre-check, not a submittal. NEC 220.87 (120.87 in the 2026 code) accepts a year of maximum demand data or a continuous 30-day recording at 15-minute intervals, existing demand taken at 125 percent, service properly protected. Adoption and interpretation vary by AHJ; confirm before submitting. © Wattif Inc.

Borderline or Over? A Recording Settles It.

The kit ships to your shop, clamps on in 15 minutes, records for 30 days, and the submittal-ready report carries your brand.

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