Three-Phase Power

Understanding Three-Phase Power

Three-phase power is the standard for professional LED installations. Understanding its principles enables proper system design and safe power distribution.

Three-Phase Basics

**Configuration:** Three separate AC lines, each offset by 120 degrees:

• Phase A
• Phase B
• Phase C
• (Neutral in Wye configuration)
• Ground

**Advantage:** Delivers more power with less current than single-phase, enabling:

• Smaller conductors
• Less voltage drop
• More efficient distribution

Three-Phase Math

**Power Formula:** P = V × I × √3 × PF

Where:

• P = Power (watts)
• V = Line-to-line voltage
• I = Current per phase
• √3 ≈ 1.732
• PF = Power factor

**Current Calculation:** I = P ÷ (V × 1.732 × PF)

Common Three-Phase Voltages

**North America:**

• 208V/120V Wye (most common commercial)
• 480V/277V Wye (industrial)
• 240V Delta (older buildings)

**International:**

• 400V/230V Wye (European standard)

Wye vs. Delta Configuration

**Wye (Star):**

• Has neutral conductor
• Two voltage options (line-line and line-neutral)
• 208V/120V or 480V/277V
• Preferred for flexibility

**Delta:**

• No neutral
• Single voltage only (line-line)
• 240V or 480V
• Less common for LED distribution

Load Balancing

**Importance:** Distribute LED panels evenly across phases:

• Prevents neutral overload
• Maximizes available power
• Reduces voltage imbalance

**Method:**

• Count panels per phase
• Adjust distribution to equalize
• Verify with amp readings

Distribution Strategy

**From Venue Power:** 1. Main disconnect 2. Company switch/distro 3. Sub-distribution panels 4. Individual panel circuits

**Touring Distros:** Purpose-built for entertainment:

• Cam-Lok or Powerlok input
• Multiple output options
• Phase indication
• Current monitoring

Cable and Connectors

**Common Connectors:**

• Cam-Lok (high power)
• Powerlock (very high power)
• Pin and sleeve (industrial)
• California style (portable)

**Cable Sizing:** Based on current per phase—use standard amperage calculations.

Safety Considerations

**Phase Rotation:** Correct rotation required for some equipment:

• Use phase rotation meter
• Verify before connecting sensitive loads

**Grounding:**

• Equipment ground essential
• Neutral-ground bond at source only
• Test ground integrity

**Voltage Verification:**

• Measure all phases before connecting
• Check phase-to-phase and phase-to-neutral
• Document readings

Troubleshooting

**Unbalanced Load:**

• Neutral carries current
• Voltage variation between phases
• Rebalance panel distribution

**Missing Phase:**

• 1/3 of wall dark
• No rotation (motors stall)
• Check connections and breakers

**High Neutral Current:**

• Harmonic distortion
• Non-linear loads
• May need oversized neutral