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

This SOP defines the standards and procedures for performing **power load calculations** for all
events produced by Maryland Productions (MP) and Event Revolution (RV). Accurate load calculations
are required to ensure electrical safety, system reliability, and compliance with equipment and
venue limits.

Incorrect load calculations can result in tripped breakers, equipment damage, or unsafe conditions.


Purpose
=======

- Ensure all power systems operate within safe limits.
- Prevent overloads, phase imbalance, and neutral failure.
- Standardize how loads are calculated and documented.
- Support proper generator and service sizing.
- Provide predictable, repeatable power planning across shows.


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

- Power technicians  
- Technical Directors  
- Lighting, audio, and video leads contributing load data  
- Warehouse staff assisting with prep calculations  
- Project Managers reviewing power scope  

Anyone approving or deploying power systems must understand and follow this SOP.


Scope
=====

This SOP applies to:

- Temporary power systems
- Venue tie-ins
- Generator-powered events
- Distros, breakouts, and branch circuits
- All lighting, audio, video, and ancillary loads

Permanent electrical installations are excluded.


Power Load Calculation Principles
=================================

All load calculations must follow these principles:

- Never exceed connector, breaker, or cable ratings.
- Always calculate **continuous load** conservatively.
- Balance loads across phases whenever possible.
- Account for startup and inrush current.
- Maintain headroom for safety and flexibility.

If load data is uncertain, assume worst case.


Gathering Load Information
==========================

Before calculating:

- Obtain equipment power requirements from:
  - Manufacturer specifications  
  - Nameplates  
  - Internal MP/RV reference data  
- Identify:
  - Voltage  
  - Amperage or wattage  
  - Phase requirements  
- Confirm whether loads are:
  - Continuous  
  - Intermittent  
  - Startup-heavy  

Accurate input data is critical.


Calculating Single-Phase Loads
==============================

- Use the formula:

  ``Watts = Volts × Amps``

- For amperage-based planning:
  - Use **80% of breaker rating** for continuous loads
- Example:
  - 20A circuit → plan for **16A max continuous**

Never plan to full breaker capacity.


Calculating Three-Phase Loads
=============================

- Determine whether the load is:
  - Balanced  
  - Single-phase on a three-phase system  
- Distribute loads evenly across:
  - Phase A  
  - Phase B  
  - Phase C  
- Monitor neutral loading when using single-phase loads.

Unbalanced phases reduce available capacity.


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

- Calculate total expected load.
- Add:
  - Startup/inrush allowance  
  - Environmental derating if applicable  
- Target generator operation at:
  - 50–75% of rated capacity  
- Avoid sustained operation above 80%.

Headroom protects generators and connected systems.


Department Load Contributions
==============================

Lighting
--------

- Fixtures and dimmers
- LED drivers and power supplies
- Control and networking equipment

Audio
-----

- Amplifiers
- Consoles
- Wireless and RF systems
- Processing racks

Video
-----

- LED walls and processors
- Projectors
- Switchers and playback systems

Ancillary
---------

- Catering
- Scenic motors
- Office or production equipment

Every department must provide accurate data.


Documenting Load Plans
======================

All power plans must document:

- Total connected load
- Per-phase distribution
- Circuit assignments
- Generator or service size
- Safety margin

Documentation must be shared with:
- Power team  
- Technical Director  
- Project Manager  

If it is not documented, it is not approved.


On-Site Verification
====================

Before energizing:

- Verify connected loads match plan.
- Confirm breaker sizes.
- Check distro labeling.
- Monitor meters during initial power-up.

Plans must be validated in reality.


Adjustments During Show
=======================

- Any added loads must be:
  - Calculated  
  - Approved  
  - Documented  
- Avoid adding loads to already near-capacity circuits.
- Communicate changes immediately.

Unplanned changes create risk.


Common Load Calculation Errors
==============================

- Ignoring startup current
- Overloading neutrals
- Assuming nameplate values are conservative
- Forgetting non-show loads
- Failing to rebalance phases

Most power failures trace back to planning errors.


Roles & Responsibilities
========================

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

- Perform and verify load calculations.
- Balance phases and monitor systems.
- Approve changes to power plans.

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

- Provide accurate load data.
- Communicate changes promptly.

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

- Ensure power scope is adequate.
- Support safety-driven power decisions.


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

- Load calculations completed and documented.
- Adequate headroom maintained.
- Phase balance verified.
- Issues reviewed post-show.

Accurate load calculations protect people and equipment.