I recently received a legend in the mail from a reader in Staten Island, N.Y., who neatly printed his letter but scrawled an illegible signature. "Larry" wrote, "I'm sending you a story that might bear checking out."

He recounted a legend I'd never heard before, which I'm calling "The Bedbug Letter." This column contains other job-related legends that I've heard only once each.As "Larry" tells it, an elderly woman found a bedbug in her sleeping berth on a train. She wrote a letter of complaint to the president of the railroad, and - to her surprise - received a prompt answer.

In a carefully worded letter the president expressed his horror at the incident and apologized profusely to the passenger, promising that nothing like this had happened before, nor would ever happen again.

But attached to the letter was a routing memo addressed to the president's secretary. This note read, "Send this SOB a copy of the bedbug letter!"

The second job-related legend, which I call "Save a Nun," came from Alice Sanvito, an electrician in St. Louis. She has heard the one about an electrocuted nun perhaps two dozen times from other electricians in her area.

The sister was bending over to reinsert a three-prong electric plug that was leaning out of its socket. Supposedly the long metal chain holding the her crucifix fell across the two power prongs, which were on top. This caused a short-circuit, which electrocuted her.

The lesson of the story is that electricians should install three-prong grounded wall plugs with the single ground prong facing up instead of down. On the bottom, the two power prongs would not become exposed so easily.

The flaw in this reasoning, to me, is that I've never seen a three-prong wall outlet installed with the ground prong facing up. And even two-prong plugs would present the same hazard if they hung halfway out of the wall.

Besides, to my knowledge - and to Sanvito's - no nun has ever died from an accident of this kind.

Job-related story No. 3, which I call "Start the Music," came from Michael Goldstein, a musician in Silver Spring, Md. He has heard it from fellow musicians who attribute it to other musicians, but never to themselves.

A famous pianist, whose identity varies - Rubinstein, or Graffman, or Serkin - is scheduled to perform a concerto as guest soloist with an equally famous orchestra, the identity of which also varies.

The pianist has rehearsed the Rachmaninoff Variations on a Theme of Paganini, which begins with the orchestra playing alone. But the orchestra has prepared Rachmaninoff's Piano Concerto No. 2, which begins with the pianist playing alone.

Evidently, the guest pianist and the orchestra have never rehearsed the work together.

On the night of the performance, as Goldstein heard the story, "Both pianist and conductor waited patiently for the other to begin, for a very long time, each one assuming that the other would begin when ready."

From the early days of color television comes a story sent by video technician John Fleetwood of Carrollton, Md.

Years ago, color TV cameras were touchier than they are today, and had to be tuned in advance of air time. One station's engineer would aim a camera at a bowl of fruit and return to the control room to set the color balance.

Before one broadcast, though, his foolproof method failed him. No matter how he adjusted the controls, the picture never looked normal: The colors were way off. Finally, just before air time, the engineer hurried from the basement control room to the studio, intending to adjust the cameras themselves.

When he arrived, he found that some practical joker had painted the bananas in the fruit bowl bright blue.