For a new system installation, is it permissible to use a series rated combination even though there is no evidence the panelboard manufacturer has the panelboard listed and marked for the specific combination of OCPDs?

For a new system installation, is it permissible to use a series rated combination even though there is no evidence the panelboard manufacturer has the panelboard listed and marked for the specific combination of OCPDs?

• A. True
• B. False
• C. Only with manufacturer approval
• D. It depends on jurisdiction

Answer: (B)

Using a series-rated arrangement is not automatically allowed just because you’re using two OCPDs in series. The installation must be specifically listed or labeled by the panelboard manufacturer for that exact pairing of the panelboard and the OCPDs. If there’s no evidence that the panelboard is listed and marked for the particular combination, you cannot proceed with that arrangement. The listing (or a labeled approval statement from the manufacturer backed by UL/appropriate certification) is what validates the series rating in a given panel. Without it, the combination hasn’t been evaluated and is not permitted. In practice, you must choose a panelboard and OCPD combination that is clearly listed for the series-rated arrangement, or obtain an official listing/label that covers it.

Using a series-rated arrangement is not automatically allowed just because you’re using two OCPDs in series. The installation must be specifically listed or labeled by the panelboard manufacturer for that exact pairing of the panelboard and the OCPDs. If there’s no evidence that the panelboard is listed and marked for the particular combination, you cannot proceed with that arrangement. The listing (or a labeled approval statement from the manufacturer backed by UL/appropriate certification) is what validates the series rating in a given panel. Without it, the combination hasn’t been evaluated and is not permitted. In practice, you must choose a panelboard and OCPD combination that is clearly listed for the series-rated arrangement, or obtain an official listing/label that covers it.