CAPE TOWN (Reuters) - South Africa’s second largest crude oil refinery, the 120,000 barrel per day plant operated by Engen, was shutdown on Friday for investigators to determine the cause of the early morning “fire incident”, the company said. Engen, which runs the plant in the east coast city of Durban, and is majority owned by Malaysia’s Petronas, said it was working hard to ensure supply of petroleum products to Africa’s most industrialised economy.