To save time, players should play a provisional ball when there is a chance that their original ball may be lost.
If a player, playing a provisional ball, fails to say "provisional ball", then the ball played is not a provisional ball and becomes the ball in play and the original ball is lost. (Rule27-2.a). Phrases like "I'll reload" or any words other than "provisional ball" are not acceptable.

A player, when taking relief or incurring a penalty under any Rule of Golf or Local Rule, must inform his marker or opponent. (Rule 9)

1. Out of Bounds. (Rule 27-1)
Out of Bounds is defined by any wall or fence bounding the course or any line defined by white stakes.

On The O'Meara Course, to the left of 1st, 2nd, 3rd, 4th, 6th, 17; to the right of the 18th holes is Out of Bounds.
On The Montgomerie Course, to the right of 4th, 9th, 10th, 11th & 13th holes is Out of Bounds.

2. Water Hazards. (Rule 26-1)
a. Water hazards are defined by yellow stakes.
b. Lateral water hazards are defined by red stakes.
Watch a short video on the rules of water hazards.27.2. Provisional Ball.
If a ball may be lost outside a water hazard or may be out of bounds, to save time the player may play another ball provisionally in accordance with Rule 27-1. The player must inform his opponent in match play or his marker or fellow-competitor in stroke play that he intends to play a provisional ball, and he must play it before he or his partner goes forward to search for the original ball.

If he fails to do so and plays another ball, that ball is not a provisional ball and becomes the ball in play, under penalty of one stroke and distance (rule 27-1): the original ball is lost.

Rule 26-1.a,
ie proceed under the stroke and distance provision of rule 27-1; or

Rule 26-1.b.
ie drop a ball behind the water hazard, keeping the point at which the original ball last crossed the margin of the water hazard directly between the hole and the spot on which the ball is dropped, with no limit to how far behind the water hazard the ball may be dropped.

If the ball was last played from the teeing ground the ball may be played from anywhere within the teeing ground and may be teed.
If the original ball is found outside the water hazard, the player must continue play with it.
If the original ball is found in the water hazard, the player may either play the original ball as it lies or continue with the ball played provisionally under Rule 26-1.
If the original ball is not found or identified within the five-minute search period, the player must continue with the ball played provisionally.

3. Immovable Obstructions. (Rule 24-2)
3-1. Immovable Obstructions.
All artificially surfaced roads and paths, bridges, notice boards seats, and shelters are immovable obstructions (Rule 24-2 applies)

3-2. Staked Trees
If a staked tree tree interferes with a player’s stance or the area of his intended swing, the ball must be lifted, without penalty, and dropped in accordance with the procedure prescribed in Rule 24-2b (Immovable Obstruction). If the ball lies in a water hazard, the player must lift and drop the ball in accordance with Rule 24-2b(i), except that the nearest point of relief must be in the water hazard and the ball must be dropped in the water hazard or the player may proceed under Rule 26. The ball may be cleaned when lifted under this Local Rule.
Exception: A player may not take relief under this Local Rule if
(a) interference by anything other than such a tree makes the stroke clearly impracticable or
(b) interference by an such a tree would occur only through use of a clearly unreasonable stroke or an unnecessarily abnormal stance, swing or direction of play.

3-3. Sprinkler Heads.
Fixed sprinkler heads are immovable obstructions and Rule 24-2 applies. In addition, if such an obstruction, within 2 club-lengths of the putting green of the hole being played intervenes on the line of play between the ball and the hole, and the ball is within 2 club-lengths of the obstruction, and is not in a hazard, nor on the putting green, the player may, without penalty, drop the ball at the nearest point, which is not nearer the hole; is not in a hazard or on a putting green and avoids interference by the obstruction.

4. Stones in Bunkers.
Stones in bunkers are movable obstructions (Rule 24-1 applies).

5. Aeration Holes on the Green.
On the putting green, a ball that comes to rest in or on an aeration hole may be placed at the nearest spot not nearer the hole that avoids the situation.

6. Environmentally sensitive areas.
6-1. Through the green or Ground Under Repair.
If a ball is in an ESA defined as through the green or ground under repair, a ball must be dropped in accordance with Rule 25-1b.
If it is known or virtually certain that a ball that has not been found is in an ESA defined as through the green or ground under repair, the player may take relief, without penalty, as prescribed in Rule 25-1c.

6-2. Water Hazard or Lateral Water Hazard.
If the ball is found in, or if it is known or virtually certain that a ball that has not been found is in an ESA defined as a water hazard or lateral water hazard, the player must, under penalty of one stroke, proceed under Rule 26-1.6-3. Interference with Stance or Area of Intended Swing.
Interference by an ESA occurs when the ESA interferes with the player’s stance or the area of his intended swing. There is no interference for line of sight.

Exception: A player may not take relief under this Local Rule if (a) interference by anything other than an ESA makes the stroke clearly impracticable or (b) interference by an ESA would occur only through use of a clearly unreasonable stroke or an unnecessarily abnormal stance, swing or direction of play.
Note: In the case of a serious breach of this Local Rule, the Committee may impose a penalty of disqualification.

7. Accidental Movement of a Ball on a Putting Green

Rules 18-2, 18-3 and 20-1 are modified as follows:

When a player's ball lies on the putting green, there is no penalty if the ball or the ball-marker is accidentally moved by the player, his partner, his opponent, or any of their caddies or equipment.

The moved ball or ball-marker must be replaces as provided in Rules 18-2, 18-3 and 20-1.

This Local Rule applies only when the player's ball or the ball-marker lies on the putting green and any movement is accidental. 
Note: If it is determined that a player's ball on the putting green was moved as a result of wind, water or some other natural cause such as the effects of gravity, the ball must be played as it lies from its new location. A ball-marker moved in such circumstances is replaced.

General Penalty for breach of Local Rule.

Match play – Loss of hole; Stroke play – Two strokes.
If a player incurs the general penalty for a breach of a Local Rule, no additional penalty under the Local Rule is applied.

8. Main Day and Alternative Day Competitions

When players have a choice between Main Day or Alternative Day participation for a single stroke competition, in terms of Rule 7-1b of the Rules of Golf, any player who elects to play on the second day of the competition is permitted to play on the competition course on the first day of the said competition when and only when playing for Carton House in an Interclub match and with the approval of the Competitions Secretary.

Temporary local rules - in force when when conditions are so abnormal that these local rules are warranted.

9. Preferred Lies / Winter Rules.
If any of the clauses of this Local Rule are to be a condition of the competition, a notice to that effect stating the number and heading of the clause, must be posted in the sign-in area near the computer. The complete rule will be posted on the web site for and on the notice board for information purposes.

9-1. Embedded Ball - Rough.
Through the green, a ball may be lifted, without penalty, cleaned and dropped as near as possible to where it lay but not nearer the hole. The ball when dropped must first strike a part of the course through the green.
Exceptions:
a. A player may not take relief under this Local Rule if the ball is embedded in sand in an area that is not closely mown.
b. A player may not take relief under this Local Rule if interference by anything other than the condition covered by this Local Rule makes the stroke clearly impracticable.

9-2. Clean & drop.
Through the green, a ball may be lifted, without penalty, cleaned and dropped within one club-length of where it lay, but not nearer the hole. The ball when dropped must first strike a part of the course through the green. A player may drop his ball only once, and it is in play when it has been dropped (Rule 20-4
Exceptions:
a. A player may not take relief under this Local Rule if the ball is lying in sand in an area that is not closely mown.
b. When a ball lies in an area covered by clause 9-3, 9-4, or 9-5, and any of clauses 9-3, 9-4 or 9-5 are a condition of the competition, then the provisions of those clauses over-ride this clause.

9-3. Placing on the fairway.
A ball lying on a closely-mown area through the green may be lifted, without penalty, and cleaned. Before lifting the ball, the player must mark its position. Having lifted the ball, he must place it on a spot within 6 inches (152.4cm ) of, and not nearer the hole, than where it originally lay, that is not in a hazard and not on a putting green.
A player may place his ball only once, and it is in play when it has been placed (Rule 20-4). If the ball fails to come to rest on the spot on which it is placed, Rule 20-3d applies. If the ball when placed comes to rest on the spot on which it is placed and it subsequently moves, there is no penalty and the ball must be played as it lies, unless the provisions of any other Rule apply.
If the player fails to mark the position of the ball before lifting it or moves the ball in any other manner, such as rolling it with a club, he incurs a penalty of one stroke.

9-4. Placing everywhere.
A ball lying through the green may be lifted, without penalty, and cleaned. Before lifting the ball, the player must mark its position. Having lifted the ball, he must place it on a spot within 6 inches (152.4cm ) of, and not nearer the hole, than where it originally lay, that is not in a hazard and not on a putting green.
A player may place his ball only once, and it is in play when it has been placed (Rule 20-4). If the ball fails to come to rest on the spot on which it is placed, Rule 20-3d applies. If the ball when placed comes to rest on the spot on which it is placed and it subsequently moves, there is no penalty and the ball must be played as it lies, unless the provisions of any other Rule apply.
If the player fails to mark the position of the ball before lifting it or moves the ball in any other manner, such as rolling it with a club, he incurs a penalty of one stroke.

9-5. Flooded bunkers and storm damaged areas of bunkers.
A player may obtain relief when a ball is lying in a partially flooded bunker, or, in an area of a bunker damaged solely through the action of heavy rain and flooding as follows:
a. play the ball as it lies; or
b. without penalty, drop a ball within the bunker, not nearer the hole, in an area which affords maximum relief; or,
c. under penalty of 1 stroke drop a ball behind the bunker, keeping the point at which the original ball lay directly between the hole and the spot on which the ball is dropped, with no limit to how far behind the bunker the ball may be dropped.
d. If the bunker is completely flooded, the player must proceed under clause c of this rule.

Note: Under clause b. or c. of this rule, in a bunker, players are not entitled to relief from any irregularities, such as footprints or other unevenness of the surface which are not attributable to heavy rain.