Western Power acting chief executive Simon Walsh said the employee needed immediate medical assistance at 1.20pm.
“The employee, a 55-year-old man, was taken by ambulance to Harvey hospital, where he later passed away,” Mr Walsh said.
“At this stage his cause of death is unclear.
“Western Power has spoken to the employee’s family and offered our full support during this time.
“As this occurred in the workplace, Western Power is following standard practice. We have advised EnergySafety and WorkSafe and begun our own investigation.
“We are all deeply saddened by this tragic incident and on behalf of everyone at Western Power, I offer our sincerest sympathies to his family, friends and colleagues.”
A WorkSafe spokeswoman said they were waiting for the results of the post mortem to establish whether the man died from electrocution or natural causes.
“That will determine whether WorkSafe gets involved or it (the investigation) stays with EnergySafety,” she said.