Preston firefighters were called to a flat off Friargate in the city centre after a fire involving a water heater.
Two fire engines and crews attended the incident at Limehouse, between the Ring Way and Friargate around 10pm on Friday.
A water heater had overheated and melted a plastic surround.
A spokesman for the fire service said: “Though there was no fire to extinguish, firefighters isolated the heater from the electrical circuit and confirmed there were no remaining hazards or possibility of fire. No-one was injured.”