Once Power Factor Correction equipment is installed, it will usually work seamlessly in the background for many years. Those £200+ a month reactive power charges have disappeared from the electricity bill, carbon emissions and maintenance requirements have been reduced, and it’s easily and often forgotten.
However, unlike more obvious pieces of equipment, there may be capacitor failures that go unnoticed. The lights don’t go out, machines don’t stop, and fuses don’t blow. Meanwhile the reactive power charges have started creeping back onto the bills, £40, £400 or more every month. In extreme cases there may be a more dramatic incident in the mains room when a capacitor system has been neglected for so long that a catastrophic failure results.