This is the season for arson documentaries. Recently CBS reran its well-known "The Fire Next Door." Now ABC has produced a "Close-Up" on the subject called "Fire for Hire."

In many ways the ABC show is more useful than the one on CBS.The traditional roles of the networks were reversed in this case. ABC went for the hard facts while CBS sketched the picture of the issue in "human interest" terms.

ABC interviewed the criminals who set the fires, the insurance agents who cope with the damages and the government officials who make the laws, as well as the victims who were so dramatically portrayed in the CBS show.

Producer/director Richard Geradu, porter Michael Connor went from coast to coast and pointedly avoided the South Bronx the CBS show's bailiwick. They demonstrate conclusively the national dimensions of the problem and point to the need for better federal policy to combat it. Arson currently is ranked by the FBI as a Part 2 crime, they say - right up there with disorderly conduct.

When the ABC team does aim for "human intrest," sometimes they choose the easy road of concentrating on children's faces and graves. They even staged a scene in which a comic cracks an arson joke so Hume can tsk-tsk about its tastelessness. The story is urgent enough without such devices.