NBC racked up the biggest non-Super Bowl night for any network since the finale of the original “Survivor” on CBS four years ago thanks to a boffo showing for the final episode of “Friends,” which averaged roughly 52 million viewers, according to preliminary nationals from Nielsen.

From 9 to 10:05 p.m., “Friends” averaged a projected 24.8 rating/54 share in adults 18-49 and 51.9 million viewers overall, the highest entertainment rating in 18-49 since the “Seinfeld” finale six years ago on NBC. It’s also the highest-rated NBC telecast of any type over that same period.

In total viewers, it’s about on par with the first “Survivor” finale on CBS in August 2000. Only three series have averaged a larger audience for their finales: “Mash” (106.0 million), “Cheers” (80.4 million) and “Seinfeld” (76.3 million).

Earlier, the “Friends” clips show (16.2/43 in adults 18-49, 35.9 million viewers overall) achieved NBC’s highest rating in Thursday’s 8 o’clock hour since May 2002 (the season finale featuring the birth of Ross and Rachel’s baby). And at 10:05, “ER” (projected 14.0/36 in adults 18-49, 29.0 million viewers overall) appears to have racked up its highest 18-49 rating in two years.

“The Tonight Show With Jay Leno,” featuring the six stars of “Friends,” soared to its highest metered-market average (10.6/27) since the night of the “Seinfeld” finale (12.4/32).

Elsewhere, CBS was second across the board with “Survivor” (6.9/18 in adults 18-49, 18.7 million viewers overall), “CSI” (6.5/14 in adults 18-49, 20.4 million viewers overall) and “Without a Trace” (5.2/12 in adults 18-49, 16.1 million viewers overall).

ABC, with a special two-hour “Extreme Makeover: Home Edition” (1.6/4 in adults 18-49, 4.9 million viewers overall) and Fox, with two hours of “Cops” repeats (1.5/4 in adults 18-49, 3.9 million viewers overall), pretty much sat on the sidelines.

Preliminary 18-49 averages for the night: NBC, 18.7/45; CBS, 6.2/15; ABC, 1.8/4; Fox, 1.5/4, tied with UPN, 1.5/4; WB, 0.9/2.

In total viewers: NBC, 25.5 million; CBS, 12.4 million; UPN, 4.5 million; ABC, 4.0 million; Fox, 3.9 million; WB, 2.6 million.