Evidence to the Pike River Royal Commission pointing to problems with a key part of the mine's power system as a cause of the fatal explosion has been labelled simplistic and outdated by the manufacturer of the device.
Testimony about the power system from Australian mining expert Tony Reczek has been accepted by the commission as the working theory on the cause of the explosion that killed 29 men on the West Coast mine on 19 November 2010.
Mr Reczek's report said the mine was rife with potential sparks due to overheating cables and an unusual power system design.
A key part of this system is a variable speed device, which was manufactured by Rockwell Automation.
Rockwell Automation says Mr Reczek had a generic and outdated understanding of how the device operates and had not researched the specific device in use at Pike River.
It says it has carried out a precise simulation of the actual conditions present at Pike River and its findings do not match Mr Reczek's.