He ought to know better.

The vandal busted for an explosion at a Brooklyn subway station is the son of an MTA worker, law-enforcement sources told the Post.

Keyshawn Brown, 16, was arrested Thursday for allegedly tossing an MTA metal sign box onto the tracks at the Nostrand Avenue station last week — creating a loud boom and smoke when it was hit by a C train.

The mother of the Brooklyn teen, part of a gang of underground mischief-makers called the “Rail Fan Conquerors,” is a subway conductor, sources said.

Investigators are probing whether Brown is also the vandal who was nearly electrocuted by the third rail in a YouTube video, sources said.

It shows the vandal dropping a red MTA sign onto the third rail at the Avenue M station in Flatlands — and the shock sends him flying. The person who posted it wrote that the teen was hospitalized for several days.

“It takes an enormous lack of common sense to trespass on subway tracks and toy with a third rail that carries 625 volts of electricity,” said transit spokesman Kevin Ortiz.

“It’s a shame, however, that the media continues to promote this asinine behavior by posting these videos for others to ­emulate.”

Since the explosion at Nostrand Avenue last Thursday morning, law-enforcement sources say confidential witnesses and Crime Stoppers tipsters have come forward about Brown and sent in videos showing his rail havoc.

Police arrested him at his Brooklyn home Tuesday night and charged with reckless endangerment and arson.

He allegedly told one witness that he threw the metal box, taken from an A train, onto the tracks out of boredom.

“I know it’s crazy, but don’t tell anybody because I could get into serious s—t,” said Brown, according to the law-enforcement sources.

One source said about the gang, “They are focused largely on stealing destination signs from subway cars.”

Brown’s Facebook page reveals his obsession with the transit system — with pictures showing an array of subway-themed outfits.

In his profile photo, he sports a knit cap bearing an A-train logo.

In another photo, he’s seen wearing an H-train Rockaway-shuttle hoodie that was sold to raise money for Hurricane Sandy relief.