A few centuries ago the steam engine was invented.  It drove great ships across the ocean and it hauled long trains.  But in the beginning the power of steam was not easily harnessed.  In fact, the boilers could suddenly explode without warning or cause.

Eventually it came to be understood that boilers made of two different kinds of metals could cause a  spark of electricity when heat was applied by the steam.  It took years to work around this problem so that steam engines were safe most of the time.