Electrical chain Comet has been fined £75,000 with nearly £25,000 costs after the death of a roof worker at a Wrexham store.
Comet had previously admitted failing to ensure the safety of Paul Alker, who fell through a skylight in 2007.
The Judge at Mold Crown Court, his honour Rhys Rowlands, said it was an "accident waiting to happen".
A previous hearing was told Mr Alker, and a colleague, had not been supplied with roofing harnesses.
Mr Alker was a labourer carrying out roofing work and died several days after falling 7.3m (24ft) through a fragile roof.
Scaffolding had been erected at the side of the store to enable the men to get on top of the roof, but neither Mr Alker nor his colleague Aaron Pugh had been supplied with harnesses.
At the time, the men were employed by Steven Smith of Wrexham Roofing Services, who was jailed for two years in 2007 after being convicted of manslaughter by gross negligence.
Comet had picked his company randomly out of Yellow Pages, and did not provide him with their own health and safety policies.
Mold Crown Court heard how Smith had given a regional surveyor assurances over the safety procedures to be followed.
However, he did none of it, and later hired safety harnesses after the accident which he placed on the roof to try and mislead investigators.
Judge Rowlands said no penalty he could impose could reflect the family's tragic loss of a life.
The question of civil compensation would have to be considered separately, he said.
He added: "If anyone would have visited the site it would have been immediately apparent that there were totally unacceptable risks being taken.
"That would have been plain to anyone who saw what was happening."
"In my judgment, this really was an accident waiting to happen.
"Both the deceased and Mr Pugh being exposed to real and pretty obvious risk."
Comet accepted its failings and responsibilities, but felt it had been misled by Smith.
It was accepted that if his work had been monitored, his failings would have been identified.
The prosecution was brought by the Health and Safety Executive (HSE).
HSE inspector, Debbie John, said: "This incident could have been avoided if the roof lights had been protected and Mr Alker had been provided with appropriate safety equipment."
Comet company secretary Andrew Stoodley said a review had taken place and a "robust contract management system" was in place.
He added: "Our thoughts and sincere condolences have been with Mr Alker's family following this tragic accident."