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NEC409/UL 508A Support

NEC409/UL 508A Support

The 2005 National Electric Code and the Underwriters Laboratory product standards have changed. GE is committed to helping our customers understand how these changes affect their products.

Through extensive product testing GE provides customers with safe and comprehensive solutions to conform to required standards and accurately rate industrial control panels.

What makes ABB better? ABB provides added application design flexibility by having tested contactors separately from overloads. This test data allows designers to obtain a high short circuit current rating (SCCR) for their control panels, as validated by the Underwriters Laboratory, when using contactors with or without overloads.



Understanding NEC Article 409 & UL 508A


UL 508A Supplement SB
UL508A is a safety standard for Industrial Control Panels adopted by Underwriters Laboratory which is an approved method in determining SCCR referenced by NEC article 409.

Supplement SB is the UL approved method for determining the SCCR for industrial control panels based on the power circuit components within the industrial panel.
What is an industrial control panel and how is it to be marked?


Components requiring an SCCR for use in UL508A industrial control panels

  • Disconnect Switches
  • branch circuit protective devices
  • branch Circuit Fuse Holders
  • Load Controllers
  • Bus Bars
  • Terminal Blocks
  • Current meters
  • Current Shunt
  • Overload Relays
  • Switches
  • Meter Socket Bases
  • Receptacles
Components NOT requiring an SCCR for use in UL508A industrial control panels

Short Circuit Current Rating (SCCR)


Feeder Components that limit SCCR Available (UL 508A SB4.3)


Establish SCCR of Individual Power Circuit Components (UL 508A SB4.2)


Building a Control Panel?


Determine the overall SCCR of the Industrial Control Panel (UL 508A SB4.4)