Template · Service and panels

Rotary phase converter for a shop single line diagram

Three-phase machines run from a single-phase service through a 15 HP converter and its own panel. Use this for a shop with three-phase machines and only single-phase power: a rotary phase converter on its own breaker and disconnect, feeding a three-phase panel for the machines.

A free template with typical ratings, conductor callouts and general notes. Open it, change what differs on your job, fill in the title block and export a PDF.

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Rotary phase converter for a shop single line diagram: three-phase machines run from a single-phase service through a 15 HP converter and its own panel. — Rotary phase converter for a shop. 17 devices on an 11 × 17 in sheet with a title block and notes column.

What the reviewer checks on this drawing

The inspector checks the conductors and breaker against the converter’s nameplate input current, the disconnect within sight of the converter, and that nothing single-phase is connected to the manufactured phase.

What the drawing shows

Every device on the sheet, in the order power reaches it.

Symbol	Label	Rating or detail	Conductors feeding it
Utility source	Utility service	120/240V 1φ 3W
Meter	Utility meter	200A socket	Service conductors, per utility
Circuit breaker	200A 2P	Main breaker
Panel	Main panel	200A bus · 120/240V
Circuit breaker	Branch breakers
To (continues off sheet)	To house loads
Circuit breaker	80A 2P	Phase converter
Disconnect switch	Disconnect	100A · within sight, of converter	2 #4 Cu + #8 G
Device	Rotary phase converter (RPC)	15 HP · 240V, 1φ input 62A
Circuit breaker	60A 3P	Main breaker	3 #4 Cu + #8 G
Panel	Three-phase panel	100A bus · 240V 3φ 3W
Circuit breaker	40A 3P	Compressor
Motor	Air compressor	7.5 HP · 230V · 22A	3 #8 Cu + #10 G
Circuit breaker	20A 3P	Mill
Motor	Milling machine	3 HP · 230V · 9.6A	3 #12 Cu + #12 G
Circuit breaker	15A 3P	Lathe
Motor	Lathe	2 HP · 230V · 6.8A	3 #12 Cu + #12 G

Notes on the sheet

Converter single-phase input from its nameplate: 62A × 125% = 77.5A. Conductors #4 Cu (85A at 75 °C), with overcurrent protection at the next standard size, 80A (NEC 455.6 and 455.7).
Disconnect within sight of the converter, opening both single-phase supply conductors (NEC 455.8).
Converter sized for the largest motor and how hard it starts, here twice the 7.5 HP compressor, and for what runs together. Follow the converter manufacturer’s sizing table.
The manufactured phase is identified wherever it is accessible (NEC 455.6(B)) and kept off single-phase loads, controls and contactor coils (NEC 455.9).
Three-phase panel has its own 60A main, so the converter output and the panel bus are protected on the three-phase side.
Motor circuits: conductors at 125% of full-load current, breakers within the limits of NEC Table 430.52. Each machine has its own controller and overload protection (NEC 430.32). Replace the motor data with the nameplates.
Machines are started only after the converter is running, and their controls drop out on a power interruption (NEC 455.21 and 455.22).

Diagram is schematic and not to scale. Field-verify existing equipment ratings. Ratings and conductor sizes shown are typical. Confirm against the adopted code, the equipment listing and a load calculation before installation. Code references are to the 2023 NEC and the 2024 Canadian Electrical Code: see references and editions.