Father-of-two Michael Buckingham, 58, died after he was trapped while working underground on a construction project at the museum, which is at the former Caphouse Colliery, near Wakefield.
The Health and Safety Executive (HSE) confirmed that two firms and the museum were told to pay a combined total of £590,000 in fines and costs by a judge at Sheffield Crown Court today.
It said the National Coal Mining Museum Trust was fined £10,000 and ordered to pay £35,000 in costs after admitting it breached the Management and Administration of Safety and Health at Mines Regulations 1993.
But the HSE said in a statement: “Unlike those of the other two defendants, the breach (by the museum) had not played a causative role in the loss of Mr Buckingham’s life.”
Barnsley-based Amalgamated Construction Ltd (AMCO) was fined a total of £110,000 with £245,000 to pay in costs after pleading guilty to a breach of the Health & Safety at Work Act plus a breach of the Management of Health and Safety at Work Regulations.
Metal Innovations Ltd (MIL), based in Cowbridge, Wales, was fined £80,000 and ordered to pay £110,000 in costs after admitting a breach of the Health and Safety at Work Act in connection with the supply of machinery.
According to the HSE, Mr Buckingham, of Grimethorpe, near Barnsley, died after he became trapped between a tunnel construction machine and a dumper loader that he was operating on January 25 2011.
The accident happened 450ft below ground.
The HSE said Mr Buckingham was an experienced miner and electrician.
He was part of a team engaged in the second phase of a £2.7 million improvement project which involved constructing 460ft of new tunnels to revitalise the visitors’ tour and increase the number of exhibition galleries.
Mr Buckingham worked for AMCO, the firm hired to build the tunnels.
The HSE said AMCO was using the two machines, which were both supplied by MIL.
It said its investigation found that the dumper was unsafe.
The inquiry found that MIL was responsible for failing to supply equipment that met the essential health and safety requirements required of all new machinery.
Instead, it said, the firm supplied a machine that was “patently dangerous in several ways”.
The HSE said AMCO failed to carry out a suitable risk assessment of the machine or the work activities.
It said the museum trust’s safety breach centred on its failing to ensure that the mine was run in accordance with all relevant safety regulations.
Following the sentencing, Mr Buckingham’s widow Gail said: “Mick was a hard-working, loving husband and family man who will always be missed. Although we are satisfied with the outcome, we would have liked responsibility to have been accepted a long time ago.”
HSE principal inspector for mines Paul Bradley said: “There were several factors that came into play that led to the very tragic death of a much-loved and respected family man. It was an incident that could have been prevented but all three parties had a role to play in how it went badly wrong.
“However, the trust’s failure did not play a direct role in the tragic loss of life, unlike the combination of failures of the other two defendants.
“It was clearly foreseeable that entrapment and crushing could result from the use of this mobile machinery, given how the work was being carried out.
“This meant Mr Buckingham had to walk backwards on occasions and operate close to other equipment within the confines of an underground roadway. Low-cost solutions could have addressed these hazards and such solutions were readily available.”
The HSE said that, at the time of the incident, no members of the public were exposed to any risks as the mining activity was taking place overnight.