John Flowers, a much loved grandfather, died after falling from an electricity pole while clearing tree branches from around power lines in Gregson Lane, Hoghton, on November 22.
Electricity North West was convicted of contravening work at height regulations by failing to ensure the work was properly planned and supervised but was cleared of another charge at Preston Crown Court.
Judge Robert Altham, imposing a £900,000 fine, said he had to put the accident itself to one side, due to the findings of the jury.
But he added: "This was a persistent failure over a long period of time.
"The need to plan for work at height is completely obvious and known.
"This was a systemic failure in that the system did not provide proper planning."
"Everyone agrees that this work ought to have been carried out from a MEWP (mobile elevating work platform).
"I'm satisfied the defendant company failed properly to plan to removal of vegetation from deadwood from poles by linesmen.
"It clearly must be a fine that is felt by the company and the shareholders."
The 63-year-old, who had two years left until retirement, had never had a day off sick in 33 years and even told his loved ones he wanted to work an extra year because he loved his job so much.
However he accidentally severed a lanyard connected to his harness as he cleared ivy growth from a pole he was working on, causing him to fall around six metres.
The jury was told a subsequent Health and Safety Executive investigation that followed his death identified "numerous problems and issues" including that two surveys - one five years earlier - had noted the dangers from ivy growth on the pole he had climbed up, but neither had been acted on.
Mr Flowers, of New Hall Lane, Preston, was a regular at Acregate Labour Club in Preston.
His wife Teresa, children and grandchildren have been in court throughout the month long case.
Today his daughter Tracy said: " It's been a very intense day.
"None of this will bring him back but we all are relieved it is now over and we can at least return to our normal lives without this hanging over us.
"We have got lots of answers throughout the trial which helps as we knew very little about the accident in which our dad lost his life whilst at work in November 2013.
"We can now have the inquest and close that chapter and remember our dad for the character he was and let him rest in peace."
John, one of five children, grew up in Moor Nook and had just celebrated his ruby wedding anniversary.
His family have described the football fanatic as "larger than life" and known for his great sense of humour.
In the aftermath of his tragic death, beautiful floral tributes were left at the scene and a resident on the road lit a candle for the family there every evening.
The court heard the firm had a safety record.
In 2002 it was convicted over a linesman who fell from a tower and died, and was given a prohibition for failing to take measures to prevent falls from height.
The costs will be decided at a further hearing.