Power Load Calculations
***********************

This SOP defines the standards and procedures for calculating, verifying, and documenting electrical
loads for all MP/RV events. Accurate load calculations are essential for safe power distribution,
system reliability, and preventing breaker trips, voltage drop, or equipment damage.

Load calculations must be completed **before** power systems are deployed.


Purpose
=======

- Ensure all power systems are operated within rated limits.
- Prevent overloads, phase imbalance, and unsafe conditions.
- Standardize how electrical loads are calculated and documented.
- Support coordination between technical departments.
- Provide a defensible reference for power planning decisions.


Who This SOP Is For
===================

- Power technicians  
- Lighting, audio, and video leads  
- Technical Directors  
- Project Managers responsible for power scope  
- Warehouse staff assisting with prep  

Anyone planning or approving power systems must understand load calculations.


Scope
=====

This SOP applies to:

- Feeder and distro load planning
- Lighting, audio, video, and auxiliary systems
- Temporary power and generator systems
- Indoor and outdoor event power

This SOP does **not** replace licensed electrical engineering where required.


Load Calculation Fundamentals
=============================

- All loads must be known or conservatively estimated.
- Continuous loads must be derated appropriately.
- Phase balance is critical for three-phase systems.
- Neutral current must be considered.
- Diversity factors must be used cautiously.

Guessing loads is unacceptable.


Load Data Sources
=================

Use the most accurate available data:

- Manufacturer specifications
- Nameplate ratings
- Power monitoring tools
- Historical job data
- Bench testing when required

When in doubt, assume worst-case.


Department Load Breakdown
=========================

Lighting
--------

- Fixture wattage (maximum draw)
- Quantity of fixtures
- Control and network devices
- Consoles and peripherals

Lighting loads often dominate the system.


Audio
-----

- Amplifier maximum draw
- Console and processing gear
- RF racks and accessories

Account for peak draw during transients.


Video
-----

- LED wall processors and tiles
- Projectors
- Cameras and switchers
- Playback systems

Video systems may have high inrush current.


Auxiliary & Support
-------------------

- FOH power
- Network switches
- Charging stations
- Work lights
- Specialty effects

Small loads add up.


Single-Phase Calculations
=========================

For single-phase loads:

- **Watts = Volts × Amps**
- Calculate amperage based on maximum wattage.
- Apply derating for continuous loads.

Example:
- 120V × 10A = 1200W


Three-Phase Calculations
========================

For balanced three-phase loads:

- **Watts = √3 × Volts × Amps**
- Balance loads evenly across phases.
- Avoid excessive neutral current.

Unbalanced systems increase risk.


Continuous Load Derating
========================

- Continuous loads (>3 hours) should not exceed:
  - **80%** of circuit rating
- Apply derating to:
  - Breakers  
  - Feeder  
  - Distro outputs  

Derating provides safety margin.


Phase Balancing
===============

- Distribute loads evenly across phases.
- Avoid concentrating high-draw equipment on one phase.
- Monitor neutral current.
- Rebalance if changes occur.

Phase imbalance causes inefficiency and overheating.


Generator Load Planning
=======================

- Calculate total connected load.
- Add startup and inrush margins.
- Target 60–80% generator capacity.
- Account for fuel consumption and runtime.
- Avoid last-minute load additions.

Generators must never be maxed out.


Documentation Requirements
==========================

Load calculations must be documented for:

- Large or complex shows
- Generator-powered events
- Multi-distro systems
- Outdoor events

Documentation should include:
- Load list by department
- Phase assignments
- Total and per-phase load
- Safety margin

Documentation supports accountability.


Verification & Testing
======================

- Verify calculations against real-world measurements.
- Use power meters when available.
- Monitor loads during setup and show.
- Adjust as needed.

Calculated loads must match reality.


Changes & Additions
===================

- Any load changes must be reviewed.
- Recalculate affected circuits.
- Do not add equipment without approval.
- Communicate changes immediately.

Unplanned additions cause failures.


Responsibilities
================

Power Technicians
-----------------

- Perform and verify load calculations.
- Balance phases.
- Monitor loads during operation.

Department Leads
----------------

- Provide accurate equipment lists.
- Communicate changes promptly.

Project Managers
----------------

- Ensure load planning is completed.
- Approve scope changes affecting power.

Warehouse Staff
---------------

- Provide accurate equipment data.
- Assist with prep verification.


Quality Control
===============

- No system energized without load planning.
- Loads remain within rated limits.
- Phase balance maintained.
- Documentation completed when required.

Load calculation discipline prevents outages.