So, what is the Blue Book value of a 1975 giant menorah?

Rabbi Yosef Langer of Chabad of S.F. can only laugh at that query.

“It’s priceless,” he says of the 22-foot-high, 14-foot-wide steel and mahogany candelabra he lights every year with the aid of a cherry picker and a torch.

But the cost of necessary maintenance to ensure that this month’s trip up the cherry picker isn’t his last is not priceless — it’s $5,000.

“We always rub it down with oil and what have you but there’s the wear and tear of craning it and shlepping it,” said Langer. “We haven’t put any major work in it before.”

The giant menorah, the centerpiece of Chabad’s yearly Union Square Chanukah festivities, was built by rock promoter Bill Graham 30 years ago for more than $30,000.

This year’s first lighting will take place 5 p.m. Sunday, Dec. 25 at Union Square, with music beginning at about 3:30 p.m.

The estimate for repair work was provided by Stage II, a lighting and set design company that stores the menorah year-round free of charge.

While Langer doesn’t predict any catastrophic events, he has noticed the menorah growing more rickety over the years. It should be safe enough for him to light the foot-long candles this year, but unless the hulking chanukiah is repaired soon, he’ll have to condemn it.

While Chabad-sponsored Chanukah lightings of huge menorahs are now ubiquitous — several Chabad groups are even wheeling out Lego menorahs the size of Hummers these days — the Bill Graham Menorah was the first of its kind. Langer even affectionately calls it the “Mama Menorah.”

“After us, [the concept] went to literally every big city in the world. Hundreds of thousands of people every year take part in these ceremonies,” he continued.

“The light of Chanukah has really lit up the world with the concept that the miraculous is still attainable.”

Langer doesn’t think he’ll need a modern-day miracle to cover his repair costs, however. Nate Ratner, an old San Francisco plumber, politico and friend of Chabad, left Langer $750 a year in his will over the next dozen or so years toward the menorah’s upkeep.

If he can raise the five grand, Langer figures Ratner’s donation will take care of day-to-day maintenance. And that way, he’ll be able to keep doing the dangerous — but fulfilling — job of lighting the big candles.

“Sometimes you get 40-mile-per-hour winds and rain and pigeons swarming. When you’re up on the cherry picker and you’re out on a limb and it’s blowing like hell, you count your blessings,” he said with a laugh.

“It can get very testy up there. But I love it.”

For more information about the Mama Menorah fund-raising drive, contact Rabbi Yosef Langer at [email protected] or (415) 668-6178.