FAULT CURRENTS TECHNICAL INFORMATION SHEET

1. Understanding Fault Currents

A fault current is the abnormally high current that flows in an electrical system during a short circuit or fault condition. Unlike normal load current, a fault current can rise rapidly to many times the system’s rated current.

Understanding fault currents is essential for several reasons:

• Safety: High fault currents can cause arc flash, conductor damage, and equipment failure if not properly contained.
• Compliance: Standards such as AS/NZS 61439 require enclosures and assemblies to withstand specific fault levels.
• Equipment Protection: Correct specification of fault ratings ensures protective devices (MCCBs, MCBs, fuses) operate safely under fault conditions.
• Enclosure Selection: The required fault current rating determines whether a standard stocked enclosure is suitable, or whether modifications and certification are necessary.

Two common ratings are considered in practice:

• Icw (withstand current): The maximum fault current the enclosure and busbar system can withstand for a short time without a protective device.
• Icc (short-circuit current): The maximum fault current the system can handle when a short-circuit protective device (SCPD) is installed.

2. AES Fault Current Compliance Services

2.1 Fault Current Requirement <10kA

• No modifications or additional testing are required for AES stocked enclosures.
• A Statement of Compliance can be issued at no cost on request.

2.2 Fault Current Requirement >10kA to ≤65kA Icw (No SCPD in Enclosure)

Typical example: generator connection enclosures.

• No physical modifications are required to AES stocked enclosures.
• Custom certification is required to confirm compliance with tested AES enclosures.
• Documentation required from customer:
  • Enclosure layout drawing
  • Busbar sizing and support details
• Certification SKU: Certification-ASNZS 61439_10kA-65kA_Icw

2.3 Fault Current Requirement >10kA to ≤65kA Icc (SCPD Fitted)

Typical example: main switchboards with MCCBs.

• Modifications to AES stocked enclosures are required.
• Custom certification is mandatory for compliance with AS/NZS 61439.
• Documentation required from customer:
  • Power circuit single-line diagram (SLD)
  • MCCB make and model details
  • Details of any other MCCB or MCB devices fitted
• Example SKUs:
  • Cam_Bracket-kA_Arc_Flash-600-L (enclosure parts/modifications)
  • Certification-ASNZS 61439_10kA-65kA_Icc (certification)

3. Summary Table

4. Contact and Next Steps

For compliance statements or certification requests, please provide the relevant documentation to AES:

AE Stainless Direct Pty Ltd
2 Computer Road, Yatala, QLD, 4207
Email: info@aestainlessdirect.com.au

AES engineers will assess the information provided and issue the required Statement of Compliance or Certification.