A sprinkler system activated and suppressed a fire at a recycling plant on Ardra Road in Enfield.
Four fire engines and 21 firefighters and officers were called to the blaze.
The unit contained around two thousands tonnes of recycling. Part of the second floor was damaged by the fire.
A London Fire Brigade spokesperson said: “This fire highlights the clear benefits of having sprinkler systems installed.
“In this case, the sprinkler system suppressed the fire and stopped it spreading.
“Sprinklers are proven to save lives and property and also allow businesses to get back to normal as soon as possible by minimising disruption."
The Brigade was called at 1414 and the fire was under control by 1535. Fire crews from Edmonton, Enfield and Tottenham fire stations attended the scene.
The cause of the fire is under investigation.