PASADENA, Calif. — If you need a good spot welder, Aidan Turner is probably not your man. The Irish-born actor spent four months learning the intricacies of spot welding, and he wasn’t bad. “I was OK. It’s really hard to do. I was assisting, and I think they saw that I wasn’t a real talent for that. I was helping out more, but it’s really tough. You have to keep moving along. You can’t stay still for a second.” He pauses.

Come to think of it, Turner says in a meeting room of a hotel, welding is really a lot like acting. At 31, Turner has kept moving, focusing on the job at hand.

“It’s quite like acting, in a way — there’s the welding analogy straightaway. When you spot weld you just need to keep moving. If you stay for a second, you burn out, so you’ve got to keep moving and keep feeding it at the same time and moving along.”

That nimbleness has led him to the role of the dashing Ross Poldark in “Masterpiece Classic’s” retelling of the “Poldark” saga, premiering on PBS Sunday.

It marks his first lead television role, though he’s played Kili in three of the “Hobbit” movies, costarred in multiple plays and portrayed the vampire in BBC America’s successful series “Being Human.”

But in the beginning, acting was no more enchanting to him than spot welding. “I kind of fell into it. I didn’t really know what I wanted to do. I finished high school and I was just sort of lost,” says Turner, who’s dressed in a blue-gray suit with narrow lapels and a pale blue shirt buttoned to the top.

“My dad’s an electrician. He’s a tradesman. My mom is an accountant, very sort of humble working class beginnings. I just knew more of what I DIDN’T want to do. Getting a trade just didn’t interest me. Going to third-level university didn’t interest me. I think I wanted to involve myself some way in the arts, but I didn’t know what I wanted to do. Acting just seemed to happen,” he says in his lilting Irish accent.

He signed up for a drama class at the Gaiety School of Acting in Dublin and suddenly the light came on, brighter than a welder’s torch. “You have one of those revelations or epiphanies or whatever you call it; I just knew this is it. This is going to be it for me. It was terrifying getting up in front of a class full of people I’d never met before, and just exhilarating because you’re right on the edge all the time, improvising or learning dialogue, and finding out about how you make that character work.

“I just found it so interesting. There was so much in it, and it introduced me — because we’re the land of saints and scholars — and we have so many playwrights and poets and literature and a plethora of these fine people. It got me reading. It got me into Oscar Wilde and John Cavanaugh and Joyce and Shaw, all of the greats. I thought, ‘I’m in really good hands here.’”

Turner never had been much of a scholar. In fact, he relished football and most of his youth was devoted to that sole passion. “I think I always had confidence as a youngster. I don’t think I was ever shy, and maybe that got me in the door, and I wasn’t afraid of what people would think. I played a lot of football as a kid and wasn’t afraid of people thinking, ‘Oh, look at this guy, he’s going to be a poncy actor,’ or anything like that. I wouldn’t have cared. I would’ve liked that sort of challenge with somebody. If that ever did happen I was ready for it.”

He was certainly ready when, at 21, he landed his first part in the Irish playwright Sean O’Casey’s “The Plough and the Stars.” “I played a character called Cpl. Stoddard. So funnily enough, I was playing a Brit in this famous Irish play, which is quite weird.”

While he was still in drama school he met his sweetheart, actress Sarah Greene. They’ve been together for a decade, but the first two years of their relationship they almost never saw each other. Turner was in New Zealand filming the “Hobbit” and Greene was working in theater. Later she landed a Tony nomination here and roles in “Penny Dreadful” and “Vikings.”

“It was tough. But we knew straightaway that we were going to make it work. And it was always worth it,” he nods. “That was a question we asked each other: is it worth it all the time? And it always was, and it still very much is. If we got through that, we can get through anything.”