I was told by a fellow golfer that if your ball hits a power line you re-hit without penalty. True?

Not exactly, although most courses would have that scenario covered by a local rule. If no local rule, play your ball as it lies. Local rule would usually say rehit no penalty.

Every course I have ever played that have power lines in play have this as a local rule...except one. But of course, on that one course, the power lines aren't really in play.

But yes, it is a local rule that the USGA allows courses to make if they deem it necessary. It seems the only logical choice when power lines cut across fairways or hover over greens. But if it takes an errant shot to hit the power lines in the first place, don't automatically assume relief.

NB. Playing the stroke again is compulsory if the Local Rule is in force.

I would say re-hit without penalty.

player wrote:

I would say re-hit without penalty.

Only if the Local Rule is in force.
A penalty otherwise.