Tapping Busbar Considerations
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Tapping Busbar Considerations

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This UL publication is from the April 2010 issue of Electrical Connections, and it may not reflect changes that have occurred since its original publication.

Many code authorities have encountered situations in which installers wish to tap busbars to accommodate the installation of fire pumps or to connect renewable energy sources such as photovoltaic systems.

This raises several questions, including the following:

  • Does this field modification affect the UL Listing of the panelboard or deadfront switchboard?
  • Are there any available guidelines for tapping the busbar?
  • What are the concerns regarding this practice?

Panelboards and deadfront switchboards are not Listed to have their busbars tapped unless there are existing holes in the busbars marked with the word Tap adjacent to the holes. Other holes in the busbar that are not marked with the word Tap are intended for the connection of overcurrent devices, other device's as identified by the product markings and in the installation instructions or other uses identified by the manufacturer.

When the electrical equipment Listing does not include product markings or instructions for tapping busbars, code authorities often ask what can be done to approve such modifications. This situation should be treated like any other field modification of Listed equipment.

Click here to download and read the paper.

For more information, visit www.ul.com

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