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So far, it has been shown how two minimum conductor sizes are established:the minimum size to avoid overheating of the conductor itself in all the locations and installation arrangements in which it is found, and the minimum size to be compatible as a “heat sink” for the overcurrent device where the conductor connects to the overcurrent device. This second size could be larger or smaller than the size that was that was obtained from Article 310 based on the heating effect in the conductor itself, but both sizes must be considered.
There is also a third minimum size to be considered: the minimum size to avoid overheating in the terminals. Section 310.15(B), Informational Note, addresses the temperature of connection points and other factors to be considered.
This Informational Note from Section 310.15(B) was introduced in the previous discussion of ampacity.
Informational Note: Table 310.15(B)(16) through Table 310.15(B)(19) are application tables for use in determining conductor sizes on loads calculated in accordance with Article 220. Allowable ampacities result from consideration of one or more of the following:Temperature compatibility with connected equipment, especially the connection points. Coordination with circuit and system overcurrent protection. Compliance with the requirements of product listings or certifications. See 110.3(B). Preservation of the safety benefits of established industry practices and standardized procedures.
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