The suffix "B" in Type NM-B nonmetallic cable signifies that the conductors have an insulation temperature rated at?

The suffix "B" in Type NM-B nonmetallic cable indicates that the conductors are rated for an insulation temperature of 90 degrees Celsius (194 degrees Fahrenheit). This temperature rating is significant because it allows the cable to be used in applications where higher operating temperatures may be encountered.

NM-B cables are commonly used for residential wiring and are designed for indoor applications, providing the flexibility and performance needed for typical household electrical systems. The higher temperature rating of 90 C ensures that the conductors can safely handle more demanding electrical loads without the risk of insulation degradation, which could lead to safety hazards such as short circuits or fire.

In contrast, the other insulation temperature ratings associated with nonmetallic cables, such as 60 C (140 F) and 75 C (167 F), correspond to other suffixes like "A" or classifications that do not offer the same thermal tolerance and performance as the "B" series. Therefore, the choice of "C" reflects an essential characteristic of the NM-B cables, allowing for their safe and effective application in various wiring projects.