Power System Studies in Los Angeles
Power system studies are engineering analyses used to evaluate the safety, performance, and reliability of commercial and industrial electrical systems. In Los Angeles, these studies are commonly required when electrical systems are installed, modified, or reviewed for permitting, inspection, or ongoing operational safety.
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This page addresses three core study types that are frequently required together: arc flash studies, short circuit studies, and protective device coordination studies. Although these analyses are often requested as separate deliverables, they are technically interconnected and must be evaluated as part of a single electrical system. Treating them as isolated tasks can lead to incomplete results, failed inspections, or unsafe operating conditions.
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In practice, power system studies are triggered by events such as new or upgraded electrical services, installation of switchgear or large equipment, tenant improvements with increased electrical load, equipment SCCR verification, safety or insurance audits, and electrical safety programs governed by NFPA 70E. In Los Angeles, these studies may also be required to support permitted electrical drawings, respond to plan check comments, or verify that installed equipment can safely withstand available fault current from the serving utility.
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Power system studies are not generic reports or paperwork exercises. They require accurate system modeling, defensible engineering assumptions, and professional judgment informed by field conditions and jurisdictional requirements. The sections below explain when power system studies are required, what each study evaluates, how the studies relate to one another, and what information is needed to produce results that can be relied upon.
What Are Power System Studies?
Power system studies are analytical evaluations of an electrical distribution system performed to understand how the system behaves under normal operation, abnormal conditions, and fault events. Their purpose is to confirm that electrical equipment can operate safely, interrupt fault current properly, and protect people and property when failures occur.
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These studies are based on a modeled representation of the installed electrical system. The model typically incorporates utility service characteristics, transformer data, conductor impedances, protective device characteristics, and equipment ratings. Where complete information is not available, engineering assumptions may be required, and the validity of the results depends on how those assumptions are developed and documented.
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In commercial and industrial facilities, power system studies are most commonly performed in connection with system changes, safety programs, or jurisdictional review. Although individual studies are often referenced by name, they are not independent analyses. Arc flash results depend on fault current and protective device clearing times, while coordination outcomes rely on accurate short circuit calculations. For this reason, power system studies are typically evaluated together as part of a single, integrated engineering effort.
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The scope of a power system study is driven by the system configuration, the purpose of the analysis, and applicable code or safety requirements. Some projects require a full suite of studies, while others may require only specific components to address a defined concern. Understanding how the studies relate to one another is critical to producing results that are both technically accurate and practically useful.
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The sections that follow describe the most common study types, when they are required, and how they are used in practice.
When Power System Studies Are Required
Power system studies are required when changes to an electrical system affect fault current levels, protective device operation, equipment ratings, or safe working conditions. In many cases, these studies are triggered by code requirements, safety standards, or jurisdictional review rather than by owner preference.
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Common situations that require one or more power system studies include:
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Installation of a new electrical service or transformer
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Electrical service upgrades or increases in available capacity
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New switchgear, panelboards, motor control centers, or large equipment
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Tenant improvements that increase connected or demand load
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Verification of equipment short-circuit current rating (SCCR)
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Replacement or modification of protective devices
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Changes to utility service affecting available fault current
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Requests from an authority having jurisdiction (AHJ) during plan check or inspection
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Electrical safety audits or insurance risk assessments
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Implementation or update of an NFPA 70E electrical safety program
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Major system modifications following equipment failure or incident review
In Los Angeles, power system studies may also be required to support permitted electrical drawings, respond to plan check comments, or confirm that installed equipment can safely withstand available fault current provided by the serving utility.
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The specific studies required—and whether they must be performed together—depend on the scope of work, the condition of the existing electrical system, and the purpose of the analysis. In many projects, short circuit, protective device coordination, and arc flash studies are evaluated together to ensure that the system is both code-compliant and operationally safe.
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How These Studies Work Together
Although arc flash, short circuit, and protective device coordination studies are often requested as separate items, they are technically interdependent and must be evaluated as part of a single electrical system. Performing one study without considering the others frequently results in incomplete, misleading, or unusable conclusions.
Short circuit analysis establishes the available fault current throughout the electrical distribution system and verifies that equipment interrupting and withstand ratings are adequate. These fault current values are then used as inputs for protective device coordination, where the operating characteristics of breakers and fuses are evaluated to ensure proper clearing during fault conditions.
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Protective device coordination directly affects arc flash results. Protective devices that clear faults quickly generally reduce incident energy levels, while excessive clearing times or miscoordination can significantly increase arc flash hazards. As a result, arc flash incident energy calculations depend not only on fault current magnitude but also on the protective device settings and coordination outcomes established during the analysis.
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Because each study relies on the results of the others, treating them as standalone exercises increases risk. A coordinated approach ensures that equipment protection, system reliability, and personnel safety are evaluated together, using consistent assumptions and defensible engineering judgment.
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This integrated perspective is especially important in existing facilities, where partial documentation, legacy equipment, or system modifications can complicate analysis. Evaluating the system as a whole allows study results to remain meaningful and actionable rather than purely theoretical.
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Arc Flash Studies
An arc flash study evaluates the potential energy released during an electrical arc fault and the associated risk to personnel working on or near energized equipment. The purpose of the study is to quantify incident energy levels, establish arc flash boundaries, and determine appropriate personal protective equipment (PPE) requirements so that electrical work can be performed safely.
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Arc flash analysis is performed in accordance with NFPA 70E and IEEE 1584, using calculated fault current values and protective device clearing times derived from the electrical system model. The results are specific to the installed equipment, upstream protection, and operating conditions at the time of the study. Generic labels, template-based calculations, or assumptions not tied to the actual system configuration do not reflect real-world risk and are not considered defensible engineering.
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In commercial and industrial facilities, arc flash studies are commonly required for switchgear, panelboards, motor control centers, and other equipment that may be accessed for operation, maintenance, or troubleshooting while energized. The results are typically used to generate arc flash warning labels and to support electrical safety programs, training, and work procedures.
Arc flash results do not exist in isolation. Incident energy levels are directly influenced by available fault current and protective device coordination. For this reason, arc flash studies are most accurate and useful when performed in conjunction with short circuit and protective device coordination studies as part of a single, integrated analysis.
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Short Circuit Studies
A short circuit study calculates the available fault current throughout an electrical distribution system and compares those values to the interrupting and withstand ratings of installed equipment. The purpose of the study is to confirm that circuit breakers, fuses, switchgear, panelboards, and other components can safely clear fault conditions without damage or catastrophic failure.
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Short circuit analysis accounts for utility contribution, transformer size and impedance, conductor characteristics, and system configuration. While utilities typically provide fault current information at the point of service, that data represents only the starting point of the analysis. Available fault current at downstream equipment must be calculated based on how the customer-owned system is actually built.
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In commercial and industrial projects, short circuit studies are commonly required when new services are installed, existing services are upgraded, or equipment is replaced or added. They are also frequently requested during plan check or inspection when equipment interrupting ratings or short-circuit current ratings (SCCR) cannot be clearly verified from the drawings or nameplates.
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Short circuit results form the technical foundation for other power system studies. Protective device coordination relies on accurate fault current values to evaluate breaker and fuse performance, and arc flash incident energy calculations depend on both fault current magnitude and protective device clearing time. Without a defensible short circuit analysis, downstream study results are inherently unreliable.
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Protective Device Coordination Studies
A protective device coordination study evaluates how circuit breakers, fuses, and other protective devices operate together during fault conditions. The objective is selective coordination, where the device closest to a fault clears first while upstream devices remain energized. Proper coordination limits the extent of outages, reduces equipment damage, and improves overall system reliability.
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Coordination studies are performed using time–current characteristic (TCC) curves derived from manufacturer data and verified fault current values established during the short circuit analysis. These curves are analyzed to confirm that protective devices operate in the intended sequence across the range of anticipated fault levels and operating conditions.
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In commercial and industrial facilities, inadequate coordination can result in nuisance tripping, widespread loss of power, or failed inspections. Coordination issues are especially common in existing systems where protective devices have been replaced, settings have been adjusted without documentation, or system configurations have changed over time.
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Protective device coordination also has a direct impact on arc flash results. Faster clearing times generally reduce incident energy levels, while excessive delays or miscoordination can significantly increase arc flash hazards. For this reason, coordination studies must be evaluated alongside short circuit and arc flash analyses as part of a single, integrated engineering effort.
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Typical Deliverables from a Power System Study
The deliverables produced as part of a power system study depend on the scope of work, the condition of the existing electrical system, and the purpose of the analysis. In most commercial and industrial projects, the following deliverables are commonly provided.
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Core Deliverables
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Updated electrical single-line diagram reflecting the modeled system configuration
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Short circuit analysis results identifying available fault current at key equipment locations
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Protective device coordination curves and recommended settings for breakers and fuses
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Arc flash incident energy calculations and arc flash boundary determinations
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Arc flash warning labels generated from calculated results
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Summary report documenting assumptions, methodology, and conclusions​
Study-Specific Outputs
Depending on project requirements, deliverables may also include:
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Detailed arc flash study documentation to support electrical safety programs
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Equipment short-circuit current rating (SCCR) verification and fault duty evaluation
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Coordination review for existing protective device settings
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Identification of non-compliant equipment or configuration conflicts
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Scope-Dependent Additions
In some cases, additional services may be required to produce usable results, such as:
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Field verification of installed equipment and conductor sizes
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Review of legacy documentation or partial as-built drawings
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Engineering recommendations for mitigation or system modification
All deliverables are based on a modeled representation of the electrical system and are specific to the configuration evaluated at the time of analysis. Changes to equipment, protective devices, utility service, or system configuration after completion may require review or update of the study results.
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Attach the correction sheet with your current drawings. We’ll tell you exactly what must be engineered, corrected, and resubmitted to satisfy plan check — then we’ll issue stamped, permit-ready revisions.
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Information Required to Begin a Study
Accurate power system studies depend on accurate system information. The quality and reliability of the results are directly tied to the data used to model the electrical distribution system. Providing complete information at the outset reduces assumptions, limits rework, and improves turnaround time.
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Preferred Information
The following information is typically required to initiate a power system study:
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Electrical single-line diagrams or as-built drawings
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Panel schedules and equipment schedules
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Manufacturer data for breakers, fuses, and protective devices
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Transformer sizes, impedances, and configurations
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Conductor sizes, lengths, and installation details
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Utility-provided fault current information, when available
When this information is current and accurate, the electrical system can be modeled efficiently with minimal assumptions.
If Information Is Missing or Incomplete
In many existing facilities, documentation is outdated, incomplete, or unavailable. When this occurs, the study scope may require one or more of the following:
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Field verification of installed equipment and conductor sizes
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Development of documented engineering assumptions based on observed conditions
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Identification of data gaps and study limitations within the final report
Any assumptions used in the analysis are explicitly documented, and their potential impact on the results is identified. Where missing information materially affects the reliability of the study, this is addressed before work proceeds.
Field Verification Scope (When Required)
Field verification may be required when equipment ratings, protective device settings, or conductor characteristics cannot be confirmed through documentation alone. The extent of field verification is project-specific and is defined as part of the study scope to ensure that results remain defensible and usable.
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Utility Coordination
Utility data is a critical input to power system studies, particularly for short circuit and arc flash analysis. Serving utilities typically provide information related to available fault current at the point of service, along with limited system characteristics. This data represents the boundary condition of the analysis rather than a complete description of the electrical system.
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Utilities do not model customer-owned electrical distribution systems, evaluate downstream equipment ratings, or verify protective device coordination. Interpreting utility-provided data and applying it to the installed electrical system is the responsibility of the engineer performing the study.
What Utilities Typically Provide
Depending on the utility and service configuration, available information may include:
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Available fault current at the point of service
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Service voltage and configuration
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Transformer ownership and basic transformer data, when applicable
This information establishes the starting point for short circuit calculations but does not account for how fault current propagates through the customer-owned system.
What Utilities Do Not Provide
Utilities generally do not:
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Calculate fault current at downstream equipment
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Verify equipment interrupting ratings or SCCR
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Evaluate protective device coordination
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Determine arc flash incident energy or PPE requirements
These analyses require a system-level electrical model and engineering judgment beyond the utility’s scope.
LADWP Notes (Los Angeles)
In Los Angeles, coordination with the Los Angeles Department of Water and Power (LADWP) often involves requesting available fault current data for a specific service location and configuration. The information provided must then be evaluated in conjunction with transformer impedance, conductor lengths, protective devices, and equipment ratings to determine fault current levels throughout the system.
Detailed guidance on requesting and interpreting LADWP fault current data is addressed separately, as utility requirements and response formats can vary.
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Study Validity, Updates, and Change Triggers
Power system study results are specific to the electrical system configuration evaluated at the time of analysis. Changes to equipment, protective devices, utility service, or system layout can affect fault current levels, coordination performance, and arc flash results.
In general, power system studies should be reviewed or updated when any of the following occur:
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Changes to utility service or available fault current
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Replacement or modification of protective devices or settings
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Installation of new switchgear, panelboards, or major equipment
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Electrical service upgrades or load increases
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System reconfiguration affecting feeder lengths or transformer characteristics
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Findings from inspections, audits, or incident investigations
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Periodic review requirements associated with electrical safety programs
In addition, electrical safety standards such as NFPA 70E establish periodic review intervals for arc flash studies, even when no system changes are apparent. Whether a full update or a limited review is required depends on the scope of change and the purpose of the study.
Detailed guidance on update requirements and review triggers is addressed separately, as these determinations are system-specific and must be evaluated using engineering judgment.
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Relationship to Electrical Design and Permitting
Power system studies are often performed in coordination with electrical design and permitting, but they serve a distinct purpose. Electrical design establishes the configuration and sizing of the electrical system, while power system studies evaluate how that system behaves under fault conditions and abnormal operation.
In many projects, power system studies are required to support permitted electrical drawings, respond to plan check comments, or verify that installed equipment meets code and safety requirements. In other cases, studies are performed after construction to support inspections, safety programs, or operational changes.
When power system studies are used in connection with permitted work, they form part of the engineer’s overall responsibility for the system. Changes to equipment, protective devices, or utility service after permitting may require the studies to be reviewed or updated to remain valid.
Power system studies should be coordinated with electrical design decisions rather than treated as standalone deliverables. Evaluating studies and design together reduces conflicts, limits rework, and improves the defensibility of both.​
How to Engage Red Dog Engineering
Power system studies are performed on a proposal basis and are scoped according to the specific electrical system, jurisdiction, and project requirements. To initiate a review, inquiries should include enough information to understand the system and the intended use of the study.
When reaching out, please include:
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A brief description of the project scope
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Project location and serving jurisdiction
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Available electrical drawings or single-line diagrams
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Panel schedules, equipment schedules, or utility information, if available
Email-based inquiries are preferred. Drawings and documentation may be attached for preliminary review. Residential projects, stamp-only requests, and template-based studies are not accepted.
Or email directly: jerry@reddog.engineering
About the Engineer
Red Dog Engineering is led by Jerry Poon, PE (California License #20878), a licensed Professional Electrical Engineer with extensive experience performing power system studies for commercial and industrial electrical systems throughout Los Angeles.
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Jerry’s background includes over a decade of hands-on MEP engineering work involving arc flash analysis, short circuit calculations, protective device coordination, SCCR verification, and utility fault current evaluation. His experience spans commercial tenant improvements, restaurants and food-service facilities, medical and dental suites, industrial equipment installations, and complex existing systems with limited documentation.
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Power system studies performed under his direction are grounded in accurate system modeling, documented assumptions, and an understanding of how electrical systems are actually built and modified in the field. This includes coordination with serving utilities, evaluation of legacy equipment, and alignment with AHJ expectations during permitting, inspection, and safety review.
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Jerry’s approach to power system studies is defined by three principles:
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Engineering Before Deliverables
Study results are the product of engineering analysis, not template outputs or software defaults. -
Defensible Assumptions and Clear Documentation
Inputs, limitations, and conclusions are explicitly documented so results can be relied upon during inspections, audits, and future system changes. -
Responsibility Through Resolution
When engaged, he remains involved to address review comments, clarify results, and support the intended use of the study.
Services are provided for commercial and industrial projects in Los Angeles and surrounding Southern California jurisdictions.