What percentage of full load should a transformer be fused at?

The appropriate percentage of full load at which a transformer should be fused is typically in the range of 200% to 250%. Fusing a transformer at this level allows for a buffer that accounts for inrush currents when the transformer is first energized, as well as temporary overloads that can occur in normal operating conditions.

Transformers can momentarily handle currents that exceed their rated capacity, so fusing at a higher percentage helps protect the transformer from nuisance tripping while still providing adequate protection against sustained overloads that could lead to overheating and potential failure.

Setting the fuse at 200% to 250% strikes a balance between protecting the transformer and allowing it to operate effectively under varying load conditions, ensuring longevity and reliability in performance.