The BC Safety Authority (BCFA) released a report Tuesday into the cause of a fire that erupted at Babine Forest Products nearly a year ago, but downplayed any link between that blaze and the one that destroyed most of the facility and killed two workers on Jan. 20.
BCFA safety manager Stephen Hinde said an investigation into the latest explosion and fire remains ongoing. The BCFA oversees safety for installation and use of such technical equipment as electrical systems, gas, boiler and pressure vessels and refrigeration systems.
On Feb. 23, 2011, a fire broke out beneath the mill's electrical room at 10:35 p.m. Workers quickly extinguished the blaze and no one was injured, but it caused $500,000 damage.
"A relatively small fire can actually cause a large amount of damage because this is expensive equipment and it's very difficult to repair," Hinde said during a teleconference call.
About four hours before, a bandsaw motor overheated but an inspection using infrared thermography showed normal conditions and a variable frequency drive (VFD), used to control the frequency of electricity supplied to the motor was bypassed, according to the report.
Hinde said VFD was bypassed because it was not working properly.
"It is quite normal when that type of equipment is not functioning properly to bypass the equipment and just operate the motor in direct drive conditions," Hinde said.
However, when the button to start the motor was pressed in the electrical room at 10:35 p.m., a large explosion was heard and flames were seen shooting out from the front of the electrical room. The fire broke out in a cable tray beneath the electrical room but investigators narrowed the likely ignition source down to a large electrical spark in a fuse in the electrical room.
It was hot enough to melt copper wiring and "the byproduct of that, which would have been some hot dust, which probably escaped from the bottom of the switch and ignited a nearby pile of sawdust on top of the cables is suspected to be the likely cause of the fire," Hinde said.
But he went on to distance the 2011 incident from the most recent disaster, saying the release of energy in 2012 was much greater.
"At this point we still have an ongoing investigation - we're not ruling out any possible cause - but the sudden and massive release of energy that we have seen for the 2012 event is highly unlikely to have been cause by an event similar to 2011."
Hinde said the subsequent repair work involved installing new equipment and met the inspector's standards.
Asked about complaints of high volumes of dry sawdust in the mill, Hinde said the BCFA is concerned primarily with electrical equipment.
"We would ensure that the electrical equipment was suitable for the environment in which it was in, and so the repaired equipment was suitable for a sawmill environment," Hinde said.
