Pick the transformer, the kVA, the secondary device and the length to it. The app gives the ten installation figures, from the primary breaker to the GEC, checks the secondary length against 240.21(C), draws the one-line and writes it as a PDF.
The app’s own example, every screen in order, 14 steps.
STEP 1 OF 14The example opens filled in: 112.5 kVA three-phase, 480 V to 120/208 V, with the answer pinned at the foot of the screen.
STEP 2 OF 14112.5 kVA picked from the chart's ratings, the secondary as 2 sets of 3/0 AWG, and a panel with main breaker.
STEP 3 OF 1410 feet of secondary conductor to the device, THHN/THWN-2 for the raceways. The one-line starts below.
STEP 4 OF 14The one-line: 175 A primary, 2/0 AWG in 2-1/2 inch EMT, SBJ and GEC 2 AWG, two raceways of 3/0, a 400 A main. 10 ft OK.
STEP 5 OF 14The ten figures: 175 A primary protection, 2/0 AWG copper, 2-1/2 inch EMT with the NEC 40% minimum of 1-1/2 inch.
STEP 6 OF 146 AWG primary EGC, 400 A panel main breaker, 312 A / 112,500 VA continuous, and 2 sets of 3/0 AWG copper.
STEP 7 OF 142 x 2-1/2 inch EMT, NEC minimum 2 inch. SBJ 2 AWG with a 4 AWG SSBJ in each raceway. GEC 2 AWG copper.
STEP 8 OF 14Figures 1 to 9 checked against the 2023 NEC, the GEC added. The answer, then how it was worked out: 135.3 A and 312.3 A.
STEP 9 OF 14The 10 ft secondary checked against each 240.21(C)(2) condition: 400 A against 400 A, and 40.4 A against 400 A. Both pass.
STEP 10 OF 14The chart's notes in 2023 NEC numbering, and where the figures differ from the chart: the primary raceway and the SBJ.
STEP 11 OF 14A separate quick calculator, kVA to amps, for any transformer. It prints in the report only when ticked.
STEP 12 OF 14The second quick calculator, amps to kVA, also separate from the sizing. Below it, the report begins.
STEP 13 OF 14The report, named Example - 112.5 kVA: save or share the PDF, or save the job.
STEP 14 OF 14The PDF, page 1: the inputs and the answer, 175 A primary on 2/0, a 400 A main on 2 sets of 3/0, 10 ft OK.
The same 14 screens with the captions burned in. No sound.
MP4, 1.9 MB, 15 seconds.
The PDF report for the same job, all 4 pages as the app writes it.
On Android, $49.99 once. Everything on this page.
The Suite has the transformer sizing chart and the kVA and amps calculators. The one-line, the secondary device choice with the 240.21(C) length check, the GEC, ratings beyond the chart and every chart figure checked against its NEC rule came out of the app and are being brought back across.
