When it comes to ladder safety, there’s a difference between three-point control and the traditional three-point contact rule. Three-point control is a climbing method that involves always using three or four limbs distributed over three or four locations for reliable support. Three-point contact involves simply coming into contact with the ladder at three points without necessarily requiring a reliable hand grip for support. Three-point contact is sometimes referred to as the three-point stance, an American football term used to describe the stance of a lineman with two feet planted in and one hand in contact with the ground.
Critical to three-point control is grasping the ladder so that one hand can bear the full weight of the body, if needed, and distributing the climber’s weight among three or four rungs. The three-point control method distributes the climber’s weight among three or four rungs, which is safest. If one foot slips during a foot transition, two hands should be grasping the ladder rungs to support the body weight. If either foot slips during a hand transition, the climber’s weight can be supported with a hand and a foot. If both feet slip during a hand transition, the climber’s weight is transferred to one or both hands.
The traditional method of climbing a ladder consists of:
- keeping the belly button between the two side rails;
- two hands holding a ladder rung or side rail; and
- one foot on a ladder rung.
The main problem with the traditional method for climbing a ladder is that the hand grip strength is inadequate to hold onto a side rail to support the entire body weight in order to prevent a fall. It is safer to grab a horizontal rung rather than a vertical side rail.
Holding a ladder rung or horizontal bar is referred to as a horizontal power grip. To help prevent an uncontrolled fall, one hand must grasp a horizontal support using a horizontal power grip at all times. Grip control in contrast with contact is critical. Side rails or vertical holds provide a contact hand grip based mostly on friction. The horizontal power grip has a 75% to 94% larger breakaway force than when gripping a vertical rail.
Based on a recent study at the University of Michigan funded by the Center for Construction Research and Training/NIOSH, neither men nor women can support their full body weight through the use of only one hand gripping a vertical side rail.
The hand that is gripping the ladder side rail will, in a fall, slide down and hit the next ladder rung 12 inches below in a quarter of a second. It takes about a third of a second for a human hand to respond and fully grasp an object. Therefore, the climber’s hand will hit and pass the ladder rung before the climber has the muscle response to fully grasp and attempt to stop the fall.
Three-point control is not three-point contact. Ladder users may increase their personal safety by using the three-point control method in addition to following the other accepted ladders safety standards.
Consider the following when climbing a ladder:
• Properly stage the ladder according to standards.
• Grasp the horizontal ladder rungs and not the vertical rails.
• Use the horizontal power hand grip.
• Grasp, rather than simply make contact.
• Distribute your weight among three or four locations.
Source: by Nick Gromicko and Ben Gromicko, InterNACHI International Association of Certified Home Inspectors