30 firefighters were called to a property in Woodmans Terrace, Ystalyfera near Swansea after a grass fire spread to a house and garage.
Mid and West Wales fire service feared there were gas canisters stored in the garage and the electricity board was called to cut off the power supply to the street.
Firefighters across Wales are launching "Project Wildfire" to help tackle deliberate grass and mountain fires.
Firefighters were called to a street in Swansea yesterday after a grass fire spread across two properties.
There was a rise in grass fires this weekend as temperatures increased across Wales.