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Code Question of the Day

The Code Question of the Day (CQD) is NECA and ELECTRICAL CONTRACTOR Magazine’s flagship National Electrical Code (NEC®) public forum for the industry. The daily distribution of Q&A generates a lively dialogue and shares relative Code-based practical responses.

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July 14, 2026

Question:

Good morning CQD – Our drawings are labeling the void under a raised floor an environmental air space rather than a plenum. Does the label change what cables are permitted in that space? Thanks, Ray C.

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July 13, 2026

Question:

Hi CQD, our inspector is pushing back on a series-rated installation where the available fault current exceeds the marked combination rating. The equipment carries the series combination marking. What does it actually take under the NEC to use series rating, and what does the inspector need before he will sign off on it? Thanks, Tom V.

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Answer:

Hello Tom, the series combination marking on the equipment is not enough if the available fault current exceeds that rating, which may be where the inspector has concerns. For a new installation, the equipment simply cannot be used where fault current exceeds the series combination rating. Section 240.86(A) provides a path for field-engineered series ratings, but that provision applies to existing installations only, not new construction. For the inspector to sign off on an engineered solution, they are likely looking for stamped drawings from a licensed professional engineer, field markings on the equipment identifying it as part of a series-rated system, and documentation showing the upstream device will always operate before the downstream device. 110.10 requires the equipment SCCR to be coordinated with the AFC, regardless of the combination marking.

Hope this helps, but further discussion with the inspector would be best to clarify their exact requirements.