In wiring installations, what would result from mixing different temperature-rated insulation?

Mixing different temperature-rated insulation in wiring installations can lead to potential thermal overload because each type of insulation is designed to handle specific maximum temperatures. When wires with varying insulation ratings are used together, the lower-rated insulation may not withstand the heat generated by current flow, especially if the wiring is subject to heavy loads or higher ambient temperatures. This can lead to the insulation degrading or even failing, increasing the risk of short circuits, electrical fires, and other hazards due to overheating. Standards set by organizations like the National Electrical Code (NEC) are designed to ensure safety by specifying the appropriate insulation for particular conditions, and deviating from these can compromise the integrity of the system.

In contrast, mixing temperature ratings doesn't directly affect voltage ratings, nor does it typically influence energy efficiency. In such cases, the risks associated with thermal overload are the primary concern.