The accident happened about 11 a.m. near Queens Village when Ronald Sampson, 51, was performing track maintenance with seven co-workers, LIRR spokesman Sam Zambuto said.
Ricardo Sanchez, general chairman of the International Brotherhood of Electrical Workers Local 589, which represented Sampson, said he may have "tripped and lost his balance," falling onto the third rail while also making contact with the steel running rail.
The third rail there carries 650 volts of direct current, compared with the 120 volts of alternating current that's typical of home electrical wires, Sanchez said.
Co-workers administered CPR until medics arrived, LIRR officials said. A worker who came to Sampson's aid was taken to Long Island Jewish Medical Center in New Hyde Park and appeared to be in "good condition" but was held overnight as a precaution, Zambuto said.
It's not unusual for railroad workers to be "bit" by the third rail, but they can survive as long they are not simultaneously in contact with the steel running rail 18 inches away, said Christopher Natale, general chairman of the Brotherhood of Railroad Signalmen Local 56.
"The worst possible thing you can do is make contact with the third rail and the running rail at the same time, because then you complete the circuit," Natale said.
Sampson, a father of four, was a successful cabinet and furniture maker before he joined the LIRR as an electrician on the third rail in 2006.
He was a jack of all trades, repairing and constructing almost anything with his hands, from motorcycles to bagel store cabinetry, said brother-in-law Larry DeLeonardis of Smithtown. "He could look in an area and see it full and completed with different cabinets and different decorations and stuff," he said.
Sampson joined the LIRR to provide his family with health care and retirement security, his relatives said.
"He talked about his job and you could see the passion he had every time you'd bring it up," DeLeonardis said. "He knew how dangerous it was. That was just part of the job to him. He was always safety first . . . he went above and beyond to ensure his safety."
About seven years ago, he and his wife Lori began building a massive expansion of their home with high ceilings and a loft -- staining, putting in flooring and everything else themselves -- and were about to put in final touch-ups, his family said. The place seemed always to be filled with friends and family, relatives said.
"He was a real man," DeLeonardis said. "In between all that he was doing, if I asked him to do something on my house, he'd be over on Sunday, putting the floor in my kitchen."
Police and LIRR personnel are investigating, Zambuto said.
"The entire LIRR is deeply shaken by this tragic loss," LIRR President Helena Williams said in a statement. "Ron was a dedicated employee and family man. It's a very sad day at the railroad today."
The last work-related LIRR fatality was on Aug. 14, 2011, when car inspector Russell E. DeCeck died after coming in contact with the third rail while working in Babylon Yard, Zambuto said.