It’s yearly in most places.
I really hope it’s just a freak occurrence and not down to lack of care.
A Scottish man I worked with nearly 20 years ago would explode if he spilled his coffee, made a mistake or someone working for him did something wrong.
He was walking back from a HV switching room as he said the floor was steaming, there was a cable going underground and it was probably red hot and failing. Maybe 30 minutes later a brand new transformer went up like a nuclear explosion, huge mushroom cloud, thick smoke and he calmly sipped on his coffee and went “that’s a fuckaroo ai” , and carried on sipping
Dave!