[julie_m]

Switch-on surges weaken fuses. Tiny bits of the fuse wire can be vaporised, and the heating and cooling with consequent expansion and contraction work-hardens it. Eventually, the switch-on current proves too much and the fuse gives up.

Some appliances with large (or just marginal) transformers have an NTC thermistor in series with the primary, or more complex thermal or electronic delay devices having contacts that short out a series resistor after a time delay to allow some flux to build up in the core.