Temporary Event Power Distribution Calculator

Free temporary event power distribution calculator for event electricians, production managers, and technical directors who need to determine total power requirements and distribution layout for concerts, festivals, corporate events, and theatrical productions. Enter your load inventory (sound, lighting, video, catering, HVAC, backline), and the calculator returns the total kW and kVA demand, recommended generator size, distribution panel configuration, and cable sizing for feeder runs from the generator to each distro location.

Temporary event power is governed by NEC Article 525 (Carnivals, Circuses, Fairs, and Similar Events) and Article 590 (Temporary Installations). Unlike permanent electrical work, event power requires rapid setup and teardown, often with generator power, long cable runs over uneven terrain, and loads that vary dramatically between sound check and show time. Undersized generators cause voltage sag, frequency drift, and ground fault issues that crash sensitive audio and video equipment. Oversized generators waste fuel and rental cost. The correct sizing accounts for inrush currents from motor loads (HVAC, refrigeration), power factor of lighting and audio loads, and a diversity factor because not all loads operate simultaneously at full capacity.

The calculator also sizes the feeder cables from the generator to each distribution panel using NEC ampacity tables with derating for ambient temperature and cable bundling. It flags any circuit that exceeds 80% of the conductor ampacity (the NEC continuous load threshold) and recommends the next larger cable size.

Pro Tip: Always spec the generator at 70-80% of its rated continuous output, not 100%. Generators deliver full rated kW only at unity power factor (PF=1.0), and most event loads have a power factor of 0.8-0.9. A "100 kW" generator with a PF=0.8 load only delivers 80 kW before the alternator current limit is reached. Also add 15-20% headroom for inrush from motor loads (HVAC units and refrigeration) starting simultaneously during load-in.

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How It Works

Enter Load Inventory

List every load by department: sound system (amplifiers, consoles, processing), lighting (conventional and LED fixtures, dimmers, moving lights), video (projectors, LED walls, cameras, switchers), catering (ovens, warmers, refrigeration), HVAC (portable AC units, heaters), and backline (guitar amps, keyboards). Enter the nameplate wattage or amperage for each.
Apply Demand and Diversity Factors

Set the demand factor for each load category. Sound and video typically run at 70-80% of nameplate. Conventional lighting dimmers rarely run at full simultaneously (50-70% diversity). LED lighting is closer to 100%. Catering loads depend on the menu and service timing. The calculator applies these factors to reduce the total from the raw nameplate sum.
Select Generator and Distribution

Based on the total kVA demand, the calculator recommends the generator size (or multiple generators for redundancy), the number of distribution panels needed, and the circuit configuration (single-phase 120/208V or three-phase 120/208V or 277/480V for large systems).
Review Cable Sizing and Layout

Check the feeder cable size for each run from the generator to each distro panel, the branch circuit loading at each panel, and any circuits that need upsizing. The calculator accounts for cable length, ambient temperature derating, and the 80% continuous load rule.

Built For

Event electricians sizing generator rentals and distro packages for outdoor concerts and festivals
Production managers preparing power plots and technical riders for touring shows and corporate events
Technical directors planning the electrical infrastructure for multi-day festivals with multiple stages
Venue managers verifying that house power capacity is sufficient for an incoming production's technical rider requirements

Features & Capabilities

Load Inventory by Department

Organizes loads by production department (sound, lighting, video, catering, HVAC, backline, misc) with typical wattage presets for common equipment. Shows the subtotal for each department and the combined total after demand and diversity factors.

Generator Sizing with Power Factor

Sizes the generator in both kW and kVA, accounting for the aggregate power factor of the load mix. Shows the difference between kW (real power) and kVA (apparent power) and explains why the generator kVA rating must exceed the total kVA demand, not just the kW.

Feeder Cable Sizing

Sizes feeder cables (typically 4/0, 2/0, or cam-lock) for each run from generator to distro panel per NEC ampacity tables. Applies ambient temperature derating and flags any run that exceeds 80% of conductor ampacity under the continuous load rule.

Three-Phase Balancing

For three-phase distribution, shows the load on each phase (A, B, C) and flags imbalances greater than 10% between phases. Phase imbalance causes neutral current, voltage asymmetry, and can trigger generator protection relays on sensitive units.

Frequently Asked Questions

How do I determine the generator size for my event?

Total all loads in kW, apply demand and diversity factors (typically 60-80% of nameplate total), divide by the expected power factor (usually 0.8-0.9) to get kVA, then add 15-20% headroom for motor inrush and unexpected loads. A medium-sized outdoor concert with a 30 kW sound system, 50 kW of lighting, 15 kW of video, and 20 kW of catering and HVAC has a nameplate total of 115 kW. After 75% diversity that becomes about 86 kW. At PF=0.85, that is 101 kVA. A 125 kVA generator provides adequate headroom.

What is the difference between kW and kVA?

kW (kilowatts) is real power — the power that actually does work (heats elements, drives motors, produces sound and light). kVA (kilovolt-amperes) is apparent power — the product of voltage and current regardless of phase angle. The ratio of kW to kVA is the power factor (PF). A purely resistive load (heaters, incandescent lights) has PF=1.0, so kW equals kVA. Reactive loads (motors, switch-mode power supplies, dimmers) have PF less than 1.0, so kVA is higher than kW. Generators are rated in kVA because the alternator current limit determines the maximum load, regardless of power factor.

What cable size do I need for a 200-amp feeder?

For a 200-amp, 3-phase feeder at 208V using cam-lock connectors, you need 4/0 AWG copper conductors (rated 230 amps per NEC Table 310.16 at 75 C). Use one cable per phase (A, B, C), one neutral, and one ground — five conductors total. For runs over 150 feet, check voltage drop and consider upsizing to 250 kcmil. Always use entertainment-rated type SC or type W portable power cable, not building wire (THHN), for temporary event installations.

What does NEC Article 525 require for event power?

NEC Article 525 covers temporary wiring for carnivals, circuses, fairs, and similar events. Key requirements include: GFCI protection on all 15 and 20 amp, 125V receptacles; overcurrent protection for all circuits; equipment grounding throughout the installation; portable cables must be listed entertainment cable (Type SC or Type W); cables must be protected from physical damage and run at least 7 feet overhead or covered with approved ramps; disconnecting means must be provided within sight of each ride, booth, or attraction. Many AHJs also apply Article 590 (Temporary Installations) requirements.

Learn More

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