The microwave crashed to the ground outside the Ashburton Library & Civic Centre Te Whare Whakatere in Baring Square on August 7.
At the time, the district council confirmed to The Ashburton Courier the incident involved "an object falling from the building".
But it would not provide further details, citing that an investigation is under way.
After an Official Information Act request from the Courier, the district council has now released a response it received from WorkSafe after it reported the incident.
The response recorded what happened.
"A staff member smelt a strong smell of smoke coming from the staff kitchen.
"He went to investigate and said he saw smoke coming out of the front of the microwave and the microwave was glowing around the door rubbers.
"The staff member got two cloths from the draw and lifted the microwave out, asking another member to unplug it."
He was concerned it would burst into flames and set off the fire alarm or damage the building.
Unable to see a fire blanket in sight, in the moment he thought the best thing would be "to get rid of it".
"So he lifted it from the kitchen and took it outside to the balcony - but the staff member did not want to put it on the balcony floor as it was timber and thought it may start a fire.
"So the staff member apparently checked to make sure no-one was below on the ground, apparently shouted out to warn any persons below, threw the microwave to the ground and then proceeded to go downstairs to clean it up.
"There was no one on the ground where the microwave landed. It made a loud noise when it landed on the ground."
The response was written by a WorkSafe notification agent who said it would not intervene "and our file will be closed".
"WorkSafe does not intervene in every matter notified to us."
