View Latest Blog Entries
Testing & Assessment Certification Standard & Regulation Aging Wires & Systems Maintenance & Sustainment Management Conference & Report Protection & Prevention Research Miscellaneous Arcing
Popular Tags
Visual Inspection High Voltage AS50881 MIL-HDBK MIL-HDBK-525 FAR AS4373 Maintenance Electromagnetic Interference (EMI) FAR 25.1707 Wire System Arcing Damage
All Tags in Alphabetical Order
2021 25.1701 25.1703 abrasion AC 33.4-3 AC 43 Accelerated Aging accessibility ADMT Aging Systems AIR6808 AIR7502 Aircraft Power System aircraft safety Aircraft Service Life Extension Program (SLEP) altitude arc damage Arc Damage Modeling Tool Arc Fault (AF) Arc Fault Circuit Breaker (AFCB) Arc Track Resistance Arcing Arcing Damage AS22759 AS22759/87 AS23053 AS29606 AS4373 AS4373 Method 704 AS50881 AS5692 AS6019 AS6324 AS81824 AS83519 AS85049 AS85485 AS85485 Wire Standard ASTM B355 ASTM B470 ASTM D150 ASTM D2671 ASTM D8355 ASTM D876 ASTM F2639 ASTM F2696 ASTM F2799 ASTM F3230 ASTM F3309 ATSRAC Attenuation Automated Wire Testing System (AWTS) Automotive Avionics backshell batteries bend radius Bent Pin Analysis Best of Lectromec Best Practice bonding Cable Cable Bend cable testing Carbon Nanotube (CNT) Certification cfr 25.1717 Chafing Chemical Testing Circuit Breaker circuit design Circuit Protection cleaning clearance Coaxial cable cold bend collision comparative analysis Compliance Component Selection Condition Based Maintenance Conductor Conductor Testing conductors conduit Connector Connector rating connector selection connector testing connectors contacts Corona Corrosion Corrosion Preventing Compound (CPC) corrosion prevention Cracking creepage D-sub data analysis data cables degradat Degradation Delamination Derating design safety development diagnostic Dielectric breakdown dielectric constant Dimensional Life disinfectant Distributed Power System DO-160 dry arc dynamic cut through E-CFR electric aircraft Electrical Aircraft Electrical Component Electrical Power Electrical Testing Electrified Vehicles Electromagnetic Interference (EMI) Electromagnetic Vulnerability (EMV) Electrostatic Discharge EMC EMF EN2235 EN3197 EN3475 EN6059 End of Service Life End of Year Energy Storage engines Environmental Environmental Cycling environmental stress ethernet eVTOL EWIS certification EWIS Component EWIS Design EWIS Failure EWIS sustainment EWIS Thermal Management EZAP FAA FAA AC 25.27 FAA AC 25.981-1C FAA Meeting failure conditions Failure Database Failure Modes and Effects Analysis (FMEA) FAQs FAR FAR 25.1703 FAR 25.1707 FAR 25.1709 Fault fault tree Fixturing Flammability fleet reliability Flex Testing fluid exposure Fluid Immersion Forced Hydrolysis fuel system fuel tank ignition Functional Hazard Assessment functional testing Fundamental Articles Fuse Future Tech galvanic corrosion Glycol Gold Gold plating Green Taxiing Grounding hand sanitizer handbook Harness Design harness protection hazard Hazard Analysis health monitoring heat shrink heat shrink tubing high current high Frequency high speed data cable High Voltage High Voltage Degradation HIRF History Hot Stamping Humidity Variation HV connector HV system ICAs IEC 60851 IEC60172 IEEE immersion insertion loss Inspection installation installation safety Instructions for Continued Airworthiness insulating material insulating tape Insulation insulation breakdown insulation resistance insulation testing interchangeability IPC-D-620 ISO 17025 Certified Lab ISO 9000 J1673 Kapton Laser Marking life limit life limited parts Life prediction life projection Lightning lightning protection liquid nitrogen lithium battery lunar Magnet wire maintainability Maintenance Maintenance costs Mandrel mean free path measurement mechanical stress Mechanical Testing MECSIP MIL-C-38999 MIL-C-85485 MIL-DTL-17 MIL-DTL-23053E MIL-DTL-3885G MIL-DTL-38999 MIL-E-25499 MIL-HDBK MIL-HDBK-1646 MIL-HDBK-217 MIL-HDBK-454 MIL-HDBK-516 MIL-HDBK-522 MIL-HDBK-525 MIL-HDBK-683 MIL-STD-1353 MIL-STD-1560 MIL-STD-1798 MIL-STD-464 MIL-T-7928 MIL-T-7928/5 MIL-T-81490 MIL-W-22759/87 MIL-W-5088 MIL–STD–5088 Military 5088 modeling moon MS3320 NASA NEMA27500 Nickel nickel plating No Fault Found OEM off gassing Outgassing Over current Overheating of Wire Harness Parallel Arcing part selection Partial Discharge partial discharge at altitude Performance physical hazard assessment Physical Testing polyamide polyimdie Polyimide-PTFE Power over Ethernet power system Power systems predictive maintenance Presentation Preventative Maintenance Program Probability of Failure Product Quality PTFE pull through Radiation Red Plague Corrosion Reduction of Hazardous Substances (RoHS) regulations relays Reliability Research Resistance Revision C Rewiring Project Risk Assessment S&T Meeting SAE SAE Committee Sanitizing Fluids Secondary Harness Protection separation Separation Requirements Series Arcing Service Life Extension Severe Wind and Moisture-Prone (SWAMP) Severity of Failure shelf life Shield Shielding Shrinkage signal signal cable Silver silver plated wire silver-plating skin depth skin effect Small aircraft smoke Solid State Circuit Breaker Space Certified Wires Splice standards Storage stored energy superconductor supportability Sustainment System Voltage Temperature Rating Temperature Variation Test methods Test Pricing Testing testing standard Thermal Circuit Breaker Thermal Endurance Thermal Index Thermal Runaway Thermal Shock Thermal Testing tin Tin plated conductors tin plating tin solder tin whiskering tin whiskers top 5 Transient Troubleshooting TWA800 UAVs UL94 USAF validation verification video Visual Inspection voltage voltage differential Voltage Tolerance volume resistivity vw-1 wet arc white paper whitelisting Winding wire Wire Ampacity Wire Bend Wire Certification Wire Comparison wire damage wire failure wire performance wire properties Wire System wire testing Wire Verification wiring components work unit code
Key Takeaways
  • IEEE 1584 provides a basis and a model for arc flash protection and necessary safe separation distance.
  • The standard targeted the necessary calculations for power distribution.
  • While there is some overlap with the aerospace industry wiring system requirements, the model’s range inhibits its use for aircraft.

Research down an unfamiliar path often includes seeking guidance from others or other fields who have gone through the process before. For those seeking information and guidance on electrical arc damage, one reference that some have considered for aerospace applications (other than the articles available on Lectromec’s website) is the IEEE 1584 standard. Here we have a brief overview, discuss concepts the document covers, and a comparison of some of the results versus arc damage data gathered for aerospace applications.

The Purpose

The IEEE document covers the potential dangers of arc flash. To quote directly from the standard

“The purpose of the guide is to enable qualified person(s) to analyze power systems for the purpose of calculating the incident energy to which employees could be exposed during operations and maintenance work. Contractors and facility owners can use this information to help provide appropriate protection for employees in accordance with the requirements of applicable electrical workplace safety standards.”

Can some of the lessons here be applied to what is needed for aerospace such as 25.1707? That is our objective in this article.

Separation Distance

The core of the IEEE 1584 document is the set of formulas for calculating the necessary safe separation distance for personnel. These long and complicated formulas cover the wide range of possibilities from low current lower voltages to higher current and higher voltages. When these are examined and applied, a set of results that are generated.

Range of the Model

Models (at least the good ones) have an acceptable range. This limits their application to scenarios that match the testing evidence. Here are the boundaries for this model:

  • Voltage: 208VAC – 15kVAC (three-phase)
  • Frequency: 50 or 60Hz
  • Fault Current for 208V – 600V: 500A – 106kA
  • Fault Current for 601V – 15kV: 200A – 65kA
  • Gap between Conductors 208V – 600V: 0.25in – 3in
  • Gap Between Conductors 601V – 15kV: 0.75in – 10in

There are also limits on the working distance and maximum enclosure size, but these are not important for the application here other than the enclosure size is compatible with aircraft enclosures.

There are a couple of items that stand out from the boundaries (at least for us in the aerospace industry)

  • The working frequency maximum is 60Hz. For most aircraft applications, AC power works on the range from 300 – 800Hz. From Lectromec’s arc testing experience, the impact on total arcing energy between 60 and 400Hz is limited. While there are finer details at work with these frequencies, the results should be close.
  • The model only works for AC systems. Those looking for DC arcing models have to look elsewhere. Lectromec has discussed DC arcing in other articles.
  • The minimum fault current for the low voltage system is 500A. Arc faults of 16AWG and smaller are likely to have fault currents below this value. For 20AWG wire, the wire length from the distribution to fault location would have to be less than 20ft (208 volts phase to phase, 0.9 ohms per 100ft of 20AWG wire). Lectromec and FAA research has shown the most severe distance from the power source for such conditions is between 100-150 ft. This is due to a combination of the fault current and circuit breaker response time.

So, while these limitations do place the model outside the parameters for most aerospace applications, we examine the model results and how they stack up against historical aerospace-centric arc test data.

The Formula

First, an item of note when reviewing the IEEE 1584 is that there are several equations whose use is dependent on the voltage level ( ≤ 600V, 600V, 2700V, and 14300V). This makes sense in the ionization caused by the event is likely to be different as is the separation distance.

Arc energy formula for arcing events with voltages below 600V. Source IEEE 1584.

The formula has several inputs that include several coefficients (the ‘k’ parameters that are based on the selected equation), the bolted fault current, configuration of conductors, and the event duration. The configuration of the conductors may be:

  • Horizontal conductors in open air
  • Horizontal conductors in conductive box
  • Vertical conductors inside a metal box
  • Vertical conductors in open air
  • Vertical conductors terminated at an insulating barrier inside of a metal box

For the examples here, the horizontal conductors in open-air values are used.

Circuit breaker response time is also part of the calculation. Those using thermal circuit breakers will have to make a best guess on the circuit breaker trip time based on the combination of system voltage and circuit plus arc resistance. Using a min/max time duration approach is suggested here.

From all of this, the formula yields an output in joules per centimeter squared. Alone, this value has little meaning. However, those with additional modeling capacity can use this as an input.

But from an application perspective, the goal is to determine safe distance. In the document, this value is specified as the arc flash boundary and is where, “the distance from a prospective arc flash where the incident energy is 5.0J/cm2”. In effect, this is the minimum “safe” distance.

Similar to the energy calculation, the Arc Flash Boundary (AFB) equation is long and requires several inputs.

Arc flash boundary formula for arcing events with voltages below 600V. Source IEEE 1584.

The following graph shows a representation of the arc flash boundary for the following configuration:

  • 10mm separation distance between conductors
  • 500A fault current
  • Horizontal in open air

Reviewing the graph, we see that an event as short as 100ms (which is practical for a 35A thermal circuit breaker), the arc flash boundary is 4.4 inches. In comparison, a 10ms arcing event (practical for 7.5A and 15A circuit breakers), sets the arc flash boundary at 1.5 inches. As expected, the increased arc duration results in a larger arc flash boundary.

IEEE 1584 Arc Duration Impact on Safe Separation Distance.

What is the issue?

The key to remember with the results and the graph shown here is the arc flash boundary considers the safe distance for human flesh. The use of human flesh for this model means a conservative estimate given that skin is more susceptible to electrical damage then aircraft components such as wiring fuel tanks and hydraulic lines.

Comparing the IEEE 1584 calculations to test data generated by Lectromec and the FAA, we find that the IEEE standard is conservative by a factor of 2 (in preparation of this article, not every configuration was examined and compared, but the data points examined confirm this factor of 2 value). While the aerospace industry does prefer conservative estimations and erring on the side of caution, creating larger separation distances creates a whole new set of challenges. In particular, attempting to route wire around other aircraft components with double separation distance is a challenge in tight areas such as the wings.


The IEEE standard does provide a good basis for the protection of personnel from electrical arcing damage and has value in its application related to power distribution systems. However, the calculations cannot be taken at face value when they are applied to other systems or the target is something other than human skin.

For a better understanding of the requirements and a means to address them, there is the Lectromec white paper discussing many of the factors that must be considered for electrical arcing and damage to aircraft components.

Michael Traskos

Michael Traskos

President, Lectromec

Michael has been involved in wire degradation and failure assessments for more than a decade. He has worked on dozens of projects assessing the reliability and qualification of EWIS components. Michael is an FAA DER with a delegated authority covering EWIS certification and the chairman of the SAE AE-8A EWIS installation committee.