An MP wants changes in health and safety rules on building sites after two companies were fined following the electrocution death of a 19-year-old.
MP Elfyn Llwyd wants lessons learned from Miall Roberts' death
Elfyn Llwyd, Plaid Cymru MP for Meirionnydd Nant Conwy, said lessons should be learned from the death of Miall Roberts in Bala three years ago.
He said one contractor should look after all health and safety on a site.
Parliament is currently debating a Corporate Manslaughter Bill with more responsibilities for company directors.
At Mold Crown Court RL Davies & Son was fined £25,000 with £15,814 costs, and Permanent Flooring was fined £6,000 with £12,000 costs after admitting health and safety at work charges.
Mr Llwyd, Plaid's parliamentary leader, said the fact that responsibility had been shared was perhaps reflected in the fines being "lower than would have been expected".
"I feel that this whole area (of responsibility) should be looked at again," he said.
"In fact Parliament is at the moment debating a Corporate Manslaughter Bill which could mean if someone dies because of serious negligence then the director of a company held responsible could face manslaughter charges."
Ultimately one company or individual should be responsible for all health and safety rules being adhered to on a building site, he added.
"I don't think this would be too difficult to put into practice, if one company was in charge then if there was a problem they would have to explain what went wrong."
Mr Llwyd said he was not certain what had happened in the case of Mr Roberts.
"I do know that serious mistakes were made. I also remember the day it happened, it was a very dark day in the Bala area.
"Miall Roberts was a lovely young man, well-liked by everyone and I sympathise with Mrs Janice Roberts his mother and Mr Gwyn Roberts, his father," he added.