“KATE & ALLIE,” 8 p.m. Monday (2)(8)--If...

“KATE & ALLIE,” 8 p.m. Monday (2)(8)--If intelligence is a barometer, “Kate & Allie” has to be judged one of TV’s best comedies. Kate McArdle (Susan Saint James) and Allie Lowell (Jane Curtin) are credible characters in amusing settings that have relevance to contemporary life.

The premise--two divorcees and their kids sharing a New York brownstone--is fraught with the perils of TV sitcomdom. The potential for zany mania lurks in every corner.

With a good cast and production staff headed by executive producers Merrill Grant and Mort Lachman, the dangers are rarely realized. A sitcom test: Could you stand living next door to Kate and Allie? Answer: yes.

This Monday’s faintly diverting episode conveys another message, though. That message is Andrea Martin.

Martin, the gorgeously gifted alumna of the brilliant SCTV comedy troupe of TV syndication, NBC and Cinemax pay cable, makes her second guest appearance on the series as Eddie, an insecure executive running the tiny cable TV station where Allie works.

When a blizzard stops key employees from reaching the studio, Eddie and the introverted Allie have to improvise their own shows to keep “Channel G” from going black. That includes Allie operating puppets and hosting a cooking show. And Eddie hosts the “Written on the Stars” call-in show (Caller: “My star is ascending.” Eddie: “Oooooh, that must hurt”) and she also plays a dog trainer who closely resembles her Edith Prickly character from SCTV. Uh . . . nice.

What this episode illustrates is how genius often becomes homogenized by even the brightest of mainstream TV. And make no mistake about it, Martin is a genius, a supreme satirist with an uncanny talent for creating characters who are at once bizarre and a millimeter from reality.

Yet on Monday, she arrives in brief gleams and glimmers and even reliably funny Edith Prickly is at her least prickliest.

Forget about the early years of “Saturday Night Live.” There has never been a comedy group on TV the equal of SCTV, whose creations reflected a blend of magical writing and performing in an environment that encouraged creativity.

Excluding Martin Short--as nerdy Ed Grimley and other UFOs on “Saturday Night Live” past--none of the group has been very glittering outside the SCTV womb. In the main, John Candy, Rick Moranis, Dave Thomas, Eugene Levy, Catherine O’Hara and Joe Flaherty are now second and third bananas, slipping on someone else’s peel. And even showing up on one of TV’s better comedies, Andrea Martin joins the blur.