What temperature is assumed for circuits rated over 100 amperes, unless marked otherwise?

For circuits rated over 100 amperes, the assumed temperature is 75° C unless indicated otherwise. This temperature rating is critical in ensuring that the wiring and components can handle the heat generated by the electrical current flowing through them without degrading or failing.

Using a standard temperature like 75° C for these circuits helps to establish consistent safety and performance parameters across various installations. This temperature is commonly recognized in industry standards for conductor insulation ratings and is also significant for calculating ampacity, as different materials and insulation types can tolerate different temperature thresholds.

If cables or conductors are rated for a higher temperature, it would normally be indicated on the cable itself, allowing electricians to make informed decisions based on the specific requirements of the installation. Therefore, understanding the assumption of 75° C is essential for ensuring safe practices in electrical installations and avoiding potential hazards due to overheating.