Study Guide - Power Distribution

Lighting Technology Study Guide: Power Distribution

Power Distribution Components

• Wires

  • Copper (or copper-clad aluminum)

  • Solid Wires: Used for permanent installations

  • Stranded Wires: Used for temporary (flexible) connections

  • American Wire Gauge (AWG):

    • Smaller number = larger diameter wire

    • Largest size: 0000 or 4/0 ("four ought")

    • Above 4/0, use "MCM" (thousands of circular mils)

      • 1 circular mil = area of a circle with a diameter of 0.001"

      • Example: AWG 4/0 = 212 MCM

    • Standard Wire Gauge (SWG): Not commonly used today

    • Metric System: Uses actual cross-sectional area in mm²

Cable Specifications

• Cable Composition:

  • Parts:

    • Conductors

    • Tensile strands

    • Strain relief clamp

    • Insulation

    • Jacketing

  • Specs:

    • AWG / Number of conductors

      • Example: 12/3 = three #12 AWG conductors

    • Jacket specifications:

      • SO (600V) or SJO (300V) neoprene

      • Voltage rating typically 600V for stage cables

Types of Cables

• Stage Cable:

  • 12/3 SO (600V)

  • Coated with neoprene, 3-conductor (black, white, green)

• Zip Cord:

  • Typically #14 to #18, two-conductor

  • Insulation allows easy splitting for setup

  • Primarily used for subtle connections on stage

• Feeder Cable:

  • Large, single-conductor used for main feeds, also known as entertainment cable

Connectors and Their Characteristics

• CamLok Connectors: Commonly used

  • Single-pole “J-lock”; essential for safe connections

  • Color-coded connectors for hot, neutral, and ground

  • Tails: Feeder cables with connectors on one end for tying in equipment

• Multi-cable:

  • Referred to as "mult", similar to stage cable but with more conductors

  • Used with multi-pin connectors (Socapex #419 with 19 pins)

  • Requires fan-out or break-out for individual fixture connections

  • Allows for quicker loading compared to individual cables

Usage Considerations

• Twofers: Allow two loads on one circuit; must have a separate container for safety

  • Similar device available: "Threefers"

  • Ampacity:

    • Current carrying capacity influenced by cable characteristics

    • Standard stage cable rated at 20A

Connectors Overview

• General:

  • Plugs (male) and receptacles (female) rated for ampacity and voltage

  • Various pin configurations to prevent cross-plugging

  • Edison Connectors:

    • Common, flat-blade household connectors, 15A or 20A version with angled blades

    • Inexpensive but do not lock

• Stage Pin Connectors:

  • Used exclusively in entertainment lighting

  • Durable, relatively inexpensive, allow for manual security

• Radial Locking Connectors (Twistlocks):

  • Round bodies, expensive but durable

  • Often require adapters for full compatibility

Power Distribution Systems

• Distribution Methods:

  • Feeder lines provide power to main disconnects/dimmers

  • Branch circuits distribute power throughout the facility

  • Disconnect: Large switch either single-phase or three-phase

• Wiring Containers:

  • Conduit: Pipe often repurposed from gas piping

  • EMT: Thin wall metal tubing, flexible on-site

  • Raceway: Long metal box for wiring access and adjustments

Specialized Equipment

• Drop Boxes:

  • Boxes attached to multi-cable, often used on grid setups

• Floor Pockets:

  • Recessed in floors with durable covers

• Receptacles:

  • Two types: cable-mount (pigtail) and panel-mount (flush-mounted)

• Patch Panels:

  • Connect multiple circuits to limited dimmers

  • Often expensive and custom made

Safety and Maintenance

• Overcurrent Protection:

  • Prevents damage by shutting down flow if too much current is drawn

  • Fuses (melting element) and circuit breakers (auto-disconnect with reset)

• Ground Fault Circuit Interruptors (GFCI):

  • Detect differences in current and trip when unbalanced

  • Used mostly in wet environments for safety