Companies have been warned that they face injury compensation claims and fines if they do not take adequate measures to prevent work injuries, after a cladding company in Llanelli was charged GBP 10,000.
Ammex Ltd was prosecuted over an incident in which employee Stephen Armstrong-Esther fell nearly four metres through an open skylight while working at the Parc Trostre retail outlet in 2005.
He suffered serious injuries, including nerve damage to his leg and fractures to his ribs and back, as well as memory and hearing loss.
Health and Safety Executive inspector Anne Marie Orrells said it is vital that employers take suitable measures to make openings in roofs safe for their workers.
"Mr Armstrong-Esther has suffered long lasting effects from his injuries since the incident which is now four years ago, and which could have been prevented," she added.
In a first-of-its-kind event in Wales, builders from around the UK were recently invited to take part in a mock trial designed to promote safety in construction.