Rule
The rules covering Immoveable Obstructions are fairly straightforward. These are obstructions that cannot be moved without unreasonable effort or without damaging the obstruction or the course. The player is allowed relief if her ball touches or is in or on the obstruction or if it physically interferes with the players area of intended stance or area of intended swing. Only when the ball is on the putting green does she get relief from her line of play from an obstruction on or off the green. If the obstruction or any abnormal condition is close enough to distract (e.g., in her line of sight or intended line of play) the player but does not meet any of the foregoing requirements there is no interference under the Rules.
However, please do remember to look at the back of the score card before playing at a new course, and perhaps revisit our own, because golf committees may adopt local rules denying relief. One of the most famous examples is the 17th Road Hole at St. Andrews, where the paved tarmac is designated as an integral part of the course, and not an obstruction, so no relief is given.
However, committees can be forgiving as well. At Roehampton Club, sprinkler heads, that lie within two club lengths of the greens allow the usual relief from swing, stance and lie, but in addition, the player can take relief from her line (please note it is whether the sprinkler heads are within two club lengths, not the player’s ball). And a final note, boundary markers such as posts, fences or walls are never classified as obstructions and no free relief is given.
Patricia Morgan, Ladies’ Golf Captain