Does Chapter 9, Table 1 of the National Electrical Code apply when conductor sizes and/or insulations are mixed?

The assertion that Chapter 9, Table 1 of the National Electrical Code does not apply when conductor sizes and/or insulations are mixed is accurate. This table specifically addresses the allowable percentage fill for a conductor’s insulation type and needs to be applied uniformly to scenarios where conductors of different types or sizes are present.

When mixing sizes and types of conductors, it's important to refer to individual tables that are more applicable, as they contain the necessary specifications for conductor size adjustments and properties associated with insulation types. The objective is to ensure safe and appropriate circuit designs, which can become compromised when applying generic fill calculations from a single standard table that doesn’t differentiate among variable conditions.

While other considerations, like similar insulation materials or specific circuit types, may apply in future discussions or calculations, they do not change the overarching guideline that Chapter 9, Table 1 is not intended for mixed scenarios. This understanding is crucial for anyone involved in electrical design and safety compliance.