Firefighters were called to the Newcastle light rail depot after reports of a fire on the roof of a tram on Wednesday night.
Newcastle Transport staff are understood to have made emergency calls after seeing smoke rising from the tram at about 7.45pm.
Two Fire and Rescue NSW crews from nearby Carrington responded.
"The call was to a battery bank smoking in a tram at the light rail depot," a Fire and Rescue NSW spokesman said.
"There was only smoke.
"We waited until power was isolated and it self-extinguished."
The tram was not in service at the time of the incident.
Newcastle Transport operator Keolis Downer is investigating what caused the electrical fault.
"A tram experienced an electrical issue in the stabling yard at Wickham," a Keolis Downer spokesperson said.
"Emergency services attended the site as a precaution.
"An investigation into the incident has commenced."
