John Doyle Construction and Exterior International receive fines of £250,000 and £100,000 respectively over the death of Jack Tangey on west London site in 2002.
Two contractors have been fined a total of £350,000 over the death of a worker at the Albion Riverside Development in Battersea, west London.
John Doyle Construction and Exterior International received the fines yesterday after a case at the Old Bailey over the death of Jack Tangey, a 29-year-old New Zealander.
He was killed on 6 August 2002 when a large timber panel, which was being lifted from the ground to the ninth floor, fell and struck him.
John Doyle Construction, Tangey's employer and a subcontractor on the job, was fined £250,000 under the Health and Safety at Work Act 1974. Exterior International, the project's man contractor, was fined £100,000.
The Health and Safety Executive's investigating inspector Emma Davies said: "Had these construction companies carried out an appropriate risk assessment, Mr Tangey would be alive today.
"This avoidable incident is an example of how badly things can go wrong when lifting operations are not planned or supervised properly."