Phase Converter Installation: What to Expect

Location Requirements

Where to Mount the Converter

The converter should be mounted where it can receive adequate airflow and where you can see and access it easily. Ideal locations:

• On a wall near your electrical panel — shorter input wire run
• Near the equipment it powers — shorter output run to machines
• Well-ventilated area — the converter generates heat during operation
• Accessible for maintenance — capacitors need occasional inspection

Mounting Height and Clearance

• Mount at eye height or above — avoid floor mounting where flooding is possible
• Minimum 12" clearance on all sides for airflow
• 18" clearance in front for access to the panel door
• The NEMA 4 enclosure can be mounted outdoors (covered) — avoid direct rain or standing water

What to Avoid

• Enclosed rooms or closets without ventilation
• Areas where temperature regularly exceeds 104°F (40°C)
• Directly next to painting or coating operations (flammable vapors)
• Areas with excessive dust without regular maintenance access

Understanding the Wiring Connections

A rotary phase converter has two sets of electrical connections: the single-phase input (from your panel) and the three-phase output (to your equipment).

Input Terminals: L1 and L2

L1 and L2 are your single-phase input connections. These connect to the two hot legs of your 230V single-phase service. In U.S. residential/commercial wiring, these are the black and red (or black and black) conductors in a two-pole circuit.

• L1 — Hot leg 1 from your panel
• L2 — Hot leg 2 from your panel
• Ground — Equipment ground, bonded to the converter enclosure
• There is no neutral connection — the converter runs on 240V, not 120V

Output Terminals: T1, T2, and T3

T1, T2, and T3 are the three-phase output connections. T1 and T2 are "hard" legs derived from your single-phase input. T3 is the "generated" leg — the synthetic third phase created by the converter.

• T1 — Output phase A (same as input L1)
• T2 — Output phase B (same as input L2)
• T3 — Output phase C (generated third leg)
• Ground — Equipment ground, bonded through to equipment ground

Breaker and Wire Sizing

The input circuit (from your panel to the converter) must be properly sized. Use this table as a starting point — always verify with your local code and electrician.

These are estimates based on NEC sizing guidelines. Your actual installation may require adjustment for wire run length (voltage drop), conduit fill, ambient temperature, and local code amendments. See our complete Reference Tables for wire and breaker charts, or consult a licensed electrician.

Output Wiring (Converter to Equipment)

The output wiring (T1, T2, T3 from converter to machine) is sized based on the equipment's rated current, not the converter HP. Use the machine's nameplate FLA and size wire at 125% per NEC — then install a properly rated disconnect and either a breaker or fuses at the machine.

Grounding and Bonding

Proper grounding is critical. Connect an equipment grounding conductor from the converter's ground terminal to the service equipment ground. See our dedicated guide: Grounding, Bonding, and NEC Code for Phase Converters.

Installation Steps Summary

1. Mount the converter in your chosen location — lag-bolted to wall or on mounting feet per the installation manual.
2. Run conduit from your main panel to the converter — size conduit for your wire gauge plus a ground conductor.
3. Install a dedicated 2-pole breaker in your main panel — sized per the table above.
4. Pull single-phase wire from panel to converter — connect L1 and L2 to input terminals, ground to enclosure ground.
5. Run conduit from converter to equipment — three conductors plus ground.
6. Install a three-phase disconnect at each machine — required by NEC for each piece of motor-driven equipment.
7. Connect T1, T2, T3 to equipment — and ground conductor through to equipment ground lug.
8. Test before full operation — see testing section below.

Testing After Installation

Pre-Power Checks

• Verify all connections are tight — no loose terminals
• Verify ground is continuous from panel to converter to equipment
• Check that all disconnects are in the off position
• Visually inspect for any loose wires, missing knockouts, or gap in conduit

First Power-Up

1. Close the main panel breaker to energize the converter (no load yet)
2. Start the converter — it should spin up smoothly within 5–10 seconds
3. Measure output voltages: T1-T2, T2-T3, T1-T3. All should be within ±10% of 230V (or 460V for transformer-coupled models)
4. If voltages look good, turn on your equipment under no load first
5. Verify equipment starts and runs without unusual noise or heat
6. Run at full load for 10–15 minutes and check converter temperature — warm is normal, hot is a sizing problem

What "Normal" Sounds Like

A properly installed and sized rotary phase converter produces a consistent low hum — the sound of the idler motor spinning. Under load, you may hear slight variation in tone. You should not hear clicking, grinding, squealing, or erratic sounds.