What is the maximum surface temperature of a transformers terminals wire leads or connections points?
Per NEMA ST-20 (2014):
- Transformers <= 10 kVA can be up to 50C above ambient with a typical maximum ambient of 25C.
- Transformers > 10 kVA can be up to 35C above ambient with a typical maximum ambient of 40C.
- Transformers with lower than standard temperature rises will have lower maximum connection point temperatures.