How to Wire a Single Phase to Three Phase Converter (Easy 5-Step Guide)

Wiring a single-phase to three-phase converter is a straightforward process when you understand the components involved. This guide walks you through the complete wiring process — from your breaker panel to your equipment — in 5 clear steps.

Important: All phase converter installations must be performed by an industrial licensed electrician. This guide is intended to help you understand the process and communicate with your electrician.

What You Need Before You Start

• Your Phoenix Phase Converter (NL, PL, NLA, NH, or PH series)
• Single-phase 230V (or 460V for NH/PH) supply from your breaker panel
• Correctly sized wire and breaker (see sizing guide below)
• Conduit for all permanent wiring runs
• A licensed industrial electrician

Step 1: Size Your Breaker and Wire

The single-phase input to your phase converter draws approximately 2x the full load amps (FLA) of your equipment. Find the FLA on your equipment nameplate, then double it.

• Breaker size: 2x equipment FLA (minimum)
• Wire gauge: Sized per NEC 310.16 for your calculated input amps and run length
• Max run length: Keep under 50 feet — longer runs require upsizing wire gauge one size

Example: A 20 HP lathe with 52A FLA needs a 104A breaker (round up to 110A) and #1 AWG copper wire for runs under 50 feet.

Step 2: Mount the Phase Converter

Mount the phase converter close to your single-phase breaker panel — ideally within 10-25 feet. The converter should be:

• Mounted on a solid wall or floor stand (not suspended)
• Level and secure — the idler motor vibrates slightly during operation
• Accessible for maintenance and inspection
• Protected from water, dust, and debris (NEMA 1 for clean indoor, NEMA 4 for harsh environments)

Step 3: Wire Single-Phase Input (Panel to Converter)

Run two hot legs (L1 and L2) plus a ground from your breaker panel to the converter input terminals. For 230V systems:

• L1: Hot leg 1 from breaker → Converter L1 terminal
• L2: Hot leg 2 from breaker → Converter L2 terminal
• Ground: Equipment ground → Converter ground lug

Use conduit for the entire run. No neutral wire is needed — phase converters run on two hot legs only.

Step 4: Connect the Idler Motor Leads

The idler motor inside your converter must be connected to its terminal block. Phoenix Phase Converters come pre-wired from the factory — do not rewire the idler motor unless instructed by our support team. If you are connecting a separate idler motor:

• 9-lead motors (NEMA 215T and smaller): Wire in YY/Y configuration for 230V
• 12-lead motors (NEMA 254T and larger): Wire in ΔΔ/Δ configuration for 230V
• Never use wire nuts — use polaris plugs or bolt-down lugs only

See our Connecting Idler Motor Leads guide and the Wiring Diagram Handbook for full diagrams.

Step 5: Wire Three-Phase Output (Converter to Equipment)

Run three output legs (T1, T2, T3) from the converter output terminals to your equipment. For 230V three-phase:

• T1, T2, T3: Three-phase output legs → Equipment motor terminals
• Ground: Ground the equipment enclosure
• Wire gauge sized at equipment FLA (NEC 310.16)
• Install a disconnect between the converter and equipment for safety

For the NL Series (auto-start), the converter starts automatically when input power is applied. For the PL Series, press the start button on the front panel to energize the converter before starting your equipment.

NLA Series — Air Compressor and HVAC Wiring

The NLA Series with AutoLink digital controller requires one additional connection for compressor and HVAC loads: the AutoLink control wires connect to your compressor pressure switch or HVAC contactor. This allows the AutoLink to manage the startup inrush current electronically. See the NLA wiring diagram in the Wiring Handbook for the complete AutoLink wiring sequence.

Quick Wire Size Reference

Related Resources

• Wiring Diagram Phase Converter Handbook — Full diagrams for all NL, PL, NH, PH, NLA series
• Phase Converter Wire Size Calculator
• Connecting Idler Motor Leads
• Step-by-Step Installation Guides
• Phase Converter FAQ