Fletcher Holdings subsidiary, Stevenson & Cook manufactured and installed the penstocks, the steel frame of the powerhouse and the spillway gate winches The rolled plates for the penstocks were transported by truck from their factory in Port Chalmers to site where a workforce of 80 men fabricated the plates using automatic submerged arc welders into sections in a purpose built workshop and then installed them in position. All welds were X-rayed during fabrication and radiographed after installation as well as pressure tested except for the concrete encased section at the intake. Stevenson & Cook lost money on the penstock contract, which contributed to the company being wound up in 1959. Fletcher Construction undertook the work to clad and roof the power house.