STINGER PRO™ ELECTRICAL CONTRACTOR OPERATING SYSTEM

Transformer

The tool takes the transformer, its kVA, the secondary device and the length of the secondary conductors. It gives ten figures for that transformer, each worked by its NEC rule, and draws the one-line.

The platform - now showing Transformer

The drawing

The one-line the Suite drew for a 112.5 kVA, 480 V to 120/208 V transformer feeding a panel with a main breaker 10 ft away. Each numbered note matches one of the ten figures in the report.

Drawing the program wrote: 175 A primary breaker, 3 × 2/0 AWG Cu in 2-1/2 in EMT, the 112.5 kVA transformer with SBJ and GEC 2 AWG Cu, then two raceways of 4 × 3/0 AWG Cu to a 400 A main breaker, 10 ft to the secondary device — OK [240.21(C)(2)].
175 A primary breaker, 3 × 2/0 AWG Cu in 2-1/2 in EMT, the 112.5 kVA transformer with SBJ and GEC 2 AWG Cu, then two raceways of 4 × 3/0 AWG Cu to a 400 A main breaker, 10 ft to the secondary device — OK [240.21(C)(2)].

The report it writes

The report the Suite wrote for this example: the primary and secondary currents, the 240.21(C) secondary conductor check, the chart’s notes and the ten figures, then the drawing.

Report page the program wrote: Page 1 of 2
Page 1 of 2
Report page the program wrote: Page 2 of 2
Page 2 of 2

Two pages: 135.3 A primary and 312.3 A secondary, the ten figures with their NEC sections, and the one-line on page 2.

The example, step by step

Entered by hand from the phone app’s example: 112.5 kVA, three-phase, 480 V to 120/208 V, to a panel with a main breaker 10 ft away.

  1. Transformer in Stinger Pro: The example in, before it is worked out: three-phase 480 V to 120/208 V, 112.5 kVA, a panel with main breaker, 10 ft of secondary conductor, THHN/THWN-2.

    STEP 1 OF 6The example in, before it is worked out: three-phase 480 V to 120/208 V, 112.5 kVA, a panel with main breaker, 10 ft of secondary conductor, THHN/THWN-2.

  2. Transformer in Stinger Pro: Size it: primary 175 A, 2/0 AWG Cu; secondary 400 A panel main breaker, 2 sets of 3/0 AWG Cu, 312 A / 112,500 VA continuous; 10 ft OK [240.21(C)(2)]. The ten figures follow.

    STEP 2 OF 6Size it: primary 175 A, 2/0 AWG Cu; secondary 400 A panel main breaker, 2 sets of 3/0 AWG Cu, 312 A / 112,500 VA continuous; 10 ft OK [240.21(C)(2)]. The ten figures follow.

  3. Transformer in Stinger Pro: Further down: the primary and secondary currents, each condition of 240.21(C)(2) checked, and the chart’s notes in 2023 NEC numbering.

    STEP 3 OF 6Further down: the primary and secondary currents, each condition of 240.21(C)(2) checked, and the chart’s notes in 2023 NEC numbering.

  4. Transformer in Stinger Pro: Where the figures differ from the chart, then the one-line: the 175 A primary breaker, 2-1/2 in EMT and the 112.5 kVA transformer.

    STEP 4 OF 6Where the figures differ from the chart, then the one-line: the 175 A primary breaker, 2-1/2 in EMT and the 112.5 kVA transformer.

  5. Transformer in Stinger Pro: The lower half of the one-line: two raceways of 4 × 3/0 AWG Cu, the 400 A main breaker panel, then the 480 V to 120/208 V sizing chart.

    STEP 5 OF 6The lower half of the one-line: two raceways of 4 × 3/0 AWG Cu, the 400 A main breaker panel, then the 480 V to 120/208 V sizing chart.

  6. Transformer in Stinger Pro: The sizing chart from 6 to 112.5 kVA, with the Sizing Notes and their NEC sections under it.

    STEP 6 OF 6The sizing chart from 6 to 112.5 kVA, with the Sizing Notes and their NEC sections under it.